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  • 1.
    Atwa, Mohamed M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Alaskalany, Ahmed
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Elgammal, Karim
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Trilayer Graphene as a Candidate Material for Phase-Change Memory Applications2016Ingår i: MRS Advances, ISSN 2316-7858, E-ISSN 1610-191X, Vol. 1, nr 20, s. 1487-1494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is pressing need in computation of a universal phase change memory consolidating the speed of RAM with the permanency of hard disk storage. A potentiated scanning tunneling microscope tip traversing the soliton separating a metallic, ABA-stacked phase and a semiconducting ABC-stacked phase in trilayer graphene has been shown to permanently transform ABA-stacked regions to ABC-stacked regions. In this study, we used density functional theory (DFT) calculations to assess the energetics of this phase-change and explore the possibility of organic functionalization using s-triazine to facilitate a reverse phase-change from rhombohedral back to Bernal in graphene trilayers. A significant deviation in the energy per simulated atom arises when s-triazine is adsorbed, favoring the transformation of the ABC phase to the ABA phase once more. A phase change memory device utilizing rapid, energy-efficient, reversible, field-induced phase-change in graphene trilayers could potentially revolutionize digital memory industry.

  • 2.
    Delekta, Szymon Sollami
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Smith, Anderson David
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Inkjet printed highly transparent and flexible graphene micro-supercapacitors2017Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, nr 21, s. 6998-7005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modern energy storage devices for portable and wearable technologies must fulfill a number of requirements, such as small size, flexibility, thinness, reliability, transparency, manufacturing simplicity and performance, in order to be competitive in an ever expanding market. To this end, a comprehensive inkjet printing process is developed for the scalable and low-cost fabrication of transparent and flexible micro-supercapacitors. These solid-state devices, with printed thin films of graphene flakes as interdigitated electrodes, exhibit excellent performance versus transparency (ranging from a single-electrode areal capacitance of 16 mu F cm(-2) at transmittance of 90% to a capacitance of 99 mu F cm(-2) at transmittance of 71%). Also, transparent and flexible devices are fabricated, showing negligible capacitance degradation during bending. The ease of manufacturing coupled with their great capacitive properties opens up new potential applications for energy storage devices ranging from portable solar cells to wearable sensors.

  • 3.
    Elgammal, Karim
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Hugosson, Håkan W.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar. Chalmers Institute of Technology, Sweden.
    Råsander, Mikael
    Bergqvist, Lars
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Delin, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Centra, SeRC - Swedish e-Science Research Centre. Uppsala University, Sweden.
    Density functional calculations of graphene-based humidity and carbon dioxide sensors: effect of silica and sapphire substrates2017Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 663, s. 23-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present dispersion-corrected density functional calculations of water and carbon dioxide molecules adsorption on graphene residing on silica and sapphire substrates. The equilibrium positions and bonding distances for the molecules are determined. Water is found to prefer the hollow site in the center of the graphene hexagon, whereas carbon dioxide prefers sites bridging carbon-carbon bonds as well as sites directly on top of carbon atoms. The energy differences between different sites are however minute - typically just a few tenths of a millielectronvolt. Overall, the molecule-graphene bonding distances are found to be in the range 3.1-3.3 (A) over circle. The carbon dioxide binding energy to graphene is found to be almost twice that of the water binding energy (around 0.17 eV compared to around 0.09 eV). The present results compare well with previous calculations, where available. Using charge density differences, we also qualitatively illustrate the effect of the different substrates and molecules on the electronic structure of the graphene sheet.

  • 4.
    Fan, Xuge
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Elgammal, Karim
    KTH, Centra, SeRC - Swedish e-Science Research Centre. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Delin, Anna
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. KTH, Centra, SeRC - Swedish e-Science Research Centre. Department of Physics and Astronomy, Materials Theory Division, Uppsala University, Box 516, SE-75120 Uppsala, Sweden.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar. Department of Electronic Devices, RWTH Aachen University, 52074 Aachen, Germany.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Humidity and CO2 gas sensing properties of double-layer graphene2018Ingår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 127, s. 576-587Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene has interesting gas sensing properties with strong responses of the graphene resistance when exposed to gases. However, the resistance response of double-layer graphene when exposed to humidity and gasses has not yet been characterized and understood. In this paper we study the resistance response of double-layer graphene when exposed to humidity and CO2, respectively. The measured response and recovery times of the graphene resistance to humidity are on the order of several hundred milliseconds. For relative humidity levels of less than ~ 3% RH, the resistance of double-layer graphene is not significantly influenced by the humidity variation. We use such a low humidity atmosphere to investigate the resistance response of double-layer graphene that is exposed to pure CO2 gas, showing a consistent response and recovery behaviour. The resistance of the double-layer graphene decreases linearly with increase of the concentration of pure CO2 gas. Density functional theory simulations indicate that double-layer graphene has a weaker gas response compared to single-layer graphene, which is in agreement with our experimental data. Our investigations contribute to improved understanding of the humidity and CO2 gas sensing properties of double-layer graphene which is important for realizing viable graphene-based gas sensors in the future.

  • 5.
    Fan, Xuge
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Mikro- och nanosystemteknik.
    Forsberg, Fredrik
    Scania Technical Centre.
    Smith, Anderson David
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system, Integrerade komponenter och kretsar.
    Schröder, Stephan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Mikro- och nanosystemteknik.
    Wagner, Stefan
    AMO GmbH.
    Östling, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system, Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektronik och inbyggda system, Integrerade komponenter och kretsar. RWTH Aachen University; AMO GmbH.
    Niklaus, Frank
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Mikro- och nanosystemteknik.
    Suspended Graphene Membranes with Attached Silicon Proof Masses as Piezoresistive Nanoelectromechanical Systems Accelerometers2019Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 19, nr 10, s. 6788-6799Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene is an atomically thin material that features unique electrical and mechanical properties, which makes it an extremely promising material for future nanoelectromechanical systems (NEMS). Recently, basic NEMS accelerometer functionality has been demonstrated by utilizing piezoresistive graphene ribbons with suspended silicon proof masses. However, the proposed graphene ribbons have limitations regarding mechanical robustness, manufacturing yield, and the maximum measurement current that can be applied across the ribbons. Here, we report on suspended graphene membranes that are fully clamped at their circumference and have attached silicon proof masses. We demonstrate their utility as piezoresistive NEMS accelerometers, and they are found to be more robust, have longer life span and higher manufacturing yield, can withstand higher measurement currents, and are able to suspend larger silicon proof masses, as compared to the previous graphene ribbon devices. These findings are an important step toward bringing ultraminiaturized piezoresistive graphene NEMS closer toward deployment in emerging applications such as in wearable electronics, biomedical implants, and internet of things (IoT) devices.

  • 6.
    Fan, Xuge
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Forsberg, Fredrik
    Scania Technical Centre.
    Smith, Anderson David
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Schröder, Stephan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Wagner, Stefan
    Faculty of Electrical Engineering and Information Technology, RWTH Aachen University.
    Östling, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Lemme, Max
    Faculty of Electrical Engineering and Information Technology, RWTH Aachen University.
    Niklaus, Frank
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Suspended graphenemembranes with attached proof masses as piezoresistive NEMS accelerometersIngår i: Artikel i tidskrift (Refereegranskat)
  • 7.
    Fan, Xuge
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Fredrik, Forsberg
    Scania Technical Centre.
    Smith, Anderson David
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Schröder, Stephan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik. Senseair AB.
    Wagner, Stefan
    AMO GmbH.
    Rödjegård, Henrik
    Senseair AB.
    Fischer, Andreas C.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik. Silex Microsystems AB, Järfälla, Sweden.
    Östling, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar. RWTH Aachen University ; AMO GmbH.
    Niklaus, Frank
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Graphene ribbons with suspended masses as transducers in ultra-small nanoelectromechanical accelerometers2019Ingår i: Nature Electronics, ISSN 2520-1131, Vol. 2, nr 9, s. 394-404Artikel i tidskrift (Refereegranskat)
    Abstract [eo]

    Nanoelectromechanical system (NEMS) sensors and actuators could be of use in the development of next-generation mobile, wearable and implantable devices. However, these NEMS devices require transducers that are ultra-small, sensitive and can be fabricated at low cost. Here, we show that suspended double-layer graphene ribbons with attached silicon proof masses can be used as combined spring–mass and piezoresistive transducers. The transducers, which are created using processes that are compatible with large-scale semiconductor manufacturing technologies, can yield NEMS accelerometers that occupy at least two orders of magnitude smaller die area than conventional state-of-the-art silicon accelerometers. With our devices, we also extract the Young’s modulus values of double-layer graphene and show that the graphene ribbons have significant built-in stresses.

  • 8.
    Fan, Xuge
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Smith, Anderson David
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Forsberg, Fredrik
    Wagner, Stefan
    Faculty of Electrical Engineering and Information Technology, RWTH Aachen University.
    Schröder, Stephan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Fisher, Andreas
    Silex Microsystems AB.
    Östling, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Lemme, Max
    Faculty of Electrical Engineering and Information Technology, RWTH Aachen University.
    Niklaus, Frank
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Manufacturing of Graphene Membranes with Suspended Silicon Proof Masses forMEMS and NEMSIngår i: Artikel i tidskrift (Refereegranskat)
  • 9. Illarionov, Y.
    et al.
    Waltl, M.
    Smith, AD
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, M.
    Grasser, T.
    Interplay between hot carrier and bias stress components in single-layer double-gated graphene field-effect transistors2015Ingår i: European Solid-State Device Research Conference, IEEE , 2015, s. 172-175Konferensbidrag (Refereegranskat)
    Abstract [en]

    We examine the interplay between the degradations associated with the bias-temperature instability (BTI) and hot carrier degradation (HCD) in single-layer double-gated graphene field-effect transistors (GFETs). Depending on the polarity of the applied BTI stress, the HCD component acting in conjuction can either accelerate or compensate the degradation. The related phenomena are studied in detail at different temperatures. Our results show that the variations of the charged trap density and carrier mobility induced by both contributions are correlated. Moreover, the electron/hole mobility behaviour agrees with the previously reported attractive/repulsive scattering asymmetry. © 2015 IEEE.

  • 10. Illarionov, Yu Yu
    et al.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, S.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Mueller, T.
    Lemme, M. C.
    Grasser, T.
    Bias-temperature instability in single-layer graphene field-effect transistors2014Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, nr 14, s. 143507-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed analysis of the bias-temperature instability (BTI) of single-layer graphene field-effect transistors. Both negative BTI and positive BTI can be benchmarked using models developed for Si technologies. In particular, recovery follows the universal relaxation trend and can be described using the established capture/emission time map approach. We thereby propose a general methodology for assessing the reliability of graphene/dielectric interfaces, which are essential building blocks of graphene devices. (C) 2014 AIP Publishing LLC.

  • 11. Illarionov, Yury
    et al.
    Smith, Anderson
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Mueller, Thomas
    Lemme, Max
    Grasser, Tibor
    Hot-Carrier Degradation and Bias-Temperature Instability in Single-Layer Graphene Field-Effect Transistors: Similarities and Differences2015Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 62, nr 11, s. 3876-3881Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed analysis of hot-carrier degradation (HCD) in graphene field-effect transistors (GFETs) and compare those findings with the bias-temperature instability (BTI). Our results show that the HCD in GFETs is recoverable, similar to its BTI counterpart. Moreover, both the degradation mechanisms strongly interact. Particular attention is paid to the dynamics of HCD recovery, which can be well fitted with the capture/emission time (CET) map model and the universal relaxation function for some stress conditions, quite similar to the BTI in both GFETs and Si technologies. The main result of this paper is an extension of our systematic method for benchmarking new graphene technologies for the case of HCD.

  • 12. Illarionov, Yu.Yu.
    et al.
    Smith, Anderson David
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Mueller, T.
    Lemme, M. C.
    Grasser, T.
    Bias-temperature instability in single-layer graphene field-effect transistors: A reliability challenge2014Ingår i: 2014 Silicon Nanoelectronics Workshop, SNW 2014, Institute of Electrical and Electronics Engineers (IEEE), 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a detailed analysis of the bias-temperature instability (BTI) of single-layer graphene field-effect transistors (GFETs). We demonstrate that the dynamics can be systematically studied when the degradation is expressed in terms of a Dirac point voltage shift. Under these prerequisites it is possible to understand and benchmark both NBTI and PBTI using models previously developed for Si technologies. In particular, we show that the capture/emission time (CET) map approach can be also applied to GFETs and that recovery in GFETs follows the same universal relaxation trend as their Si counterparts. While the measured defect densities can still be considerably larger than those known from Si technology, the dynamics of BTI are in general comparable, allowing for quantitative benchmarking of the graphene/dielectric interface quality.

  • 13. Illarionov, Yu.Yu.
    et al.
    Waltl, M.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, M. C.
    Crasser, T.
    Impact of hot carrier stress on the defect density and mobility in double-gated graphene field-effect transistors2015Ingår i: EUROSOI-ULIS 2015 - 2015 Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon, 2015, s. 81-84Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study the impact of hot-carrier degradation (HCD) on the performance of graphene field-effect transistors (GFETs) for different polarities of HC and bias stress. Our results show that the impact of HCD consists in a change of both charged defect density and carrier mobility. At the same time, the mobility degradation agrees with an attractive/repulsive scattering asymmetry and can be understood based on the analysis of the defect density variation.

  • 14. Illarionov, Y.Yu.
    et al.
    Waltl, M.
    Smith, Anderson David
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, M. C.
    Grasser, T.
    Bias-temperature instability on the back gate of single-layer double-gated graphene field-effect transistors2016Ingår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 55, nr 4, artikel-id 04EP03Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the positive and negative bias-temperature instabilities (PBTI and NBTI) on the back gate of single-layer double-gated graphene fieldeffect transistors (GFETs). By analyzing the resulting degradation at different stress times and oxide fields we show that there is a significant asymmetry between PBTI and NBTI with respect to their dependences on these parameters. Finally, we compare the results obtained on the high-k top gate and SiO2 back gate of the same device and show that SiO2 gate is more stable with respect to BTI.

  • 15. Kataria, S.
    et al.
    Wagner, S.
    Ruhkopf, J.
    Gahoi, A.
    Pandey, H.
    Bornemann, R.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    Univ Siegen, Germany.
    Chemical vapor deposited graphene: From synthesis to applications2014Ingår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 211, nr 11, s. 2439-2449Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Graphene is a material with enormous potential for numerous applications. Therefore, significant efforts are dedicated to large-scale graphene production using a chemical vapor deposition (CVD) technique. In addition, research is directed at developing methods to incorporate graphene in established production technologies and process flows. In this paper, we present a brief review of available CVD methods for graphene synthesis. We also discuss scalable methods to transfer graphene onto desired substrates. Finally, we discuss potential applications that would benefit from a fully scaled, semiconductor technology compatible production process.

  • 16.
    Lemme, Max C.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Graphene for More Moore and More Than Moore applications2012Ingår i: IEEE Silicon Nanoelectronics Workshop, SNW, IEEE , 2012, s. 6243322-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Graphene has caught the attention of the electronic device community as a potential future option for More Moore and More Than Moore devices and applications. This is owed to its remarkable material properties, which include ballistic conductance over several hundred nanometers or charge carrier mobilities of several 100.000 cm 2/Vs in pristine graphene. Furthermore, standard CMOS technology may be applied to graphene in order to make devices. Integrated graphene devices, however, are performance limited by scattering due to defects in the graphene and its dielectric environment [1, 2] and high contact resistance [3, 4]. In addition, graphene has no energy band gap (Figure 1) and hence graphene MOSFETs (GFETs) cannot be switched off, but instead show ambipolar behaviour [5]. This has steered interest away from logic to analog radio frequency (RF) applications [6, 7]. This talk will systematically compare the expected RF performance of realistic GFETs with current silicon CMOS technology [8]. GFETs slightly lag behind in maximum cut-off frequency F T,max (Figure 2) up to a carrier mobility of 3000 cm 2/Vs, where they can achieve similar RF performance as 65nm silicon FETs. While a strongly nonlinear voltage-dependent gate capacitance inherently limits performance, other parasitics such as contact resistance are expected to be optimized as GFET process technology improves.

  • 17.
    Lemme, Max C.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Alternative graphene devices: Beyond field effect transistors2012Ingår i: Device Research Conference (DRC), 2012 70th Annual, IEEE , 2012, s. 24a-24bKonferensbidrag (Refereegranskat)
    Abstract [en]

    The future manufacturability of graphene devices depends on the availability of large-scale graphene fabrication methods. While chemical vapor deposition and epitaxy from silicon carbide both promise scalability, they are not (yet) fully compatible with silicon technology. Direct growth of graphene on insulating substrates would be a major step, but is still at a very early stage [1]. This has implications on potential entry points of graphene as an add-on to mainstream silicon technology, which will be discussed in the talk.

  • 18.
    Naiini, Maziar M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    University of Siegen, Germany .
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Embedded Graphene Photodetectors for Silicon Photonics2014Ingår i: Device Research Conference (DRC), 2014 72nd Annual, IEEE conference proceedings, 2014, s. 43-44Konferensbidrag (Refereegranskat)
    Abstract [en]

    Graphene has extraordinary electronic and optoelectronic properties such as high carrier mobility, large charge-carrier concentrations, tunability via electrostatic doping, wavelength-independent absorption, and relatively low dissipation rates [1]. The combination of its electro-optical properties with its manufacturability and CMOS integrability makes graphene an extremely promising candidate for active photonic devices [2,3]. Because of its two-dimensional appearance, graphene has a limited light absorption, which is not enough to fulfill the requirements of silicon photonics technology. Recently, the integration of graphene with silicon waveguides [4,5] has been shown for on-chip applications [6]. In these solutions graphene is placed on top and outside of the waveguide yielding only limited light-graphene interaction. We introduce novel photo-detector architecture by embedding CVD-graphene inside the slot layer of deposited high-k slot waveguides that are compatible with back-end-of-the-line manufacturing of photonic integrated circuits (PICs). This approach leads to a high light-graphene interaction due to the high mode concentration in the slot region[7]. This results in enhanced absorption and enables a very compact photodetector design.

  • 19.
    Quellmalz, Arne
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Smith, Anderson David
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Elgammal, Karim
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Fan, Xuge
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Delin, Anna
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Östling, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Lemme, Max C.
    Chair of Electronic Devices, RWTH Aachen University.
    Gylfason, Kristinn
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Niklaus, Frank
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Influence of Humidity on Contact Resistance in Graphene Devices2018Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 48, s. 41738-41746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrical contact resistance at metal–graphene interfaces can significantly degrade the properties of graphene devices and is currently hindering the full exploitation of graphene’s potential. Therefore, the influence of environmental factors, such as humidity, on the metal–graphene contact resistance is of interest for all graphene devices that operate without hermetic packaging. We experimentally studied the influence of humidity on bottom-contacted chemical-vapor-deposited (CVD) graphene–gold contacts, by extracting the contact resistance from transmission line model (TLM) test structures. Our results indicate that the contact resistance is not significantly affected by changes in relative humidity (RH). This behavior is in contrast to the measured humidity sensitivity  of graphene’s sheet resistance. In addition, we employ density functional theory (DFT) simulations to support our experimental observations. Our DFT simulation results demonstrate that the electronic structure of the graphene sheet on top of silica is much more sensitive to adsorbed water molecules than the charge density at the interface between gold and graphene. Thus, we predict no degradation of device performance by alterations in contact resistance when such contacts are exposed to humidity. This knowledge underlines that bottom-contacting of graphene is a viable approach for a variety of graphene devices and the back end of the line integration on top of conventional integrated circuits.

  • 20.
    Rodriguez, Saul
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    Rusu, Ana
    Static Nonlinearity in Graphene Field Effect Transistors2014Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, nr 8, s. 3001-3003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The static linearity performance metrics of the graphene-based field effect transistor (GFET) transconductor are studied and modeled. Closed expressions are proposed for second-and third-order harmonic distortion (HD2, HD3), second-and third-order intermodulation distortion (Delta IM2, Delta IM3), and second-and third-order intercept points (A(IIP2), A(IIP3)). The expressions are validated through large-signal simulations using a GFET VerilogA analytical model and a commercial circuit simulator. The proposed expressions can be used during circuit design to predict the GFET biasing conditions at which linearity requirements are met.

  • 21.
    Rodriguez, Saul
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fregonese, Sebastien
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A Comprehensive Graphene FET Model for Circuit Design2014Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, nr 4, s. 1199-1206Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the last years, graphene-based field-effect transistors (GFETs) have shown outstanding RF performance; therefore, they have attracted considerable attention from the electronic devices and circuits communities. At the same time, analytical models that predict the electrical characteristics of GFETs have evolved rapidly. These models, however, have a complexity level that can only be handled with the help of a circuit simulator. On the other hand, analog circuit designers require simple models that enable them to carry out fast hand calculations, i.e., to create circuits using small-signal hybrid-pi models, calculate figures of merit, estimate gains, pole-zero positions, and so on. This paper presents a comprehensive GFET model that is simple enough for being used in hand calculations during circuit design and at the same time, it is accurate enough to capture the electrical characteristics of the devices in the operating regions of interest. Closed analytical expressions are provided for the drain current I-D, small-signal transconductance gain g(m), output resistance r(o), and parasitic capacitances C-gs and C-gd. In addition, figures of merit, such as intrinsic voltage gain A(V), transconductance efficiency g(m)/I-D, and transit frequency f(T) are presented. The proposed model has been compared to a complete analytical model and also to measured data available in current literature. The results show that the proposed model follows closely to both the complete analytical model and the measured data; therefore, it can be successfully applied in the design of GFET analog circuits.

  • 22.
    Smith, Anderson
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Graphene-based Devices for More than Moore Applications2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Moore's law has defined the semiconductor industry for the past 50 years. Devices continue to become smaller and increasingly integrated into the world around us. Beginning with personal computers, devices have become integrated into watches, phones, cars, clothing and tablets among other things. These devices have expanded in their functionality as well as their ability to communicate with each other through the internet. Further, devices have increasingly been required to have diverse of functionality. This combination of smaller devices coupled with diversification of device functionality has become known as more than Moore. In this thesis, more than Moore applications of graphene are explored in-depth.

    Graphene was discovered experimentally in 2004 and since then has fueled tremendous research into its various potential applications. Graphene is a desirable candidate for many applications because of its impressive electronic and mechanical properties. It is stronger than steel, the thinnest known material, and has high electrical conductivity and mobility. In this thesis, the potentials of graphene are examined for pressure sensors, humidity sensors and transistors.

    Through the course of this work, high sensitivity graphene pressure sensors are developed. These sensors are orders of magnitude more sensitive than competing technologies such as silicon nanowires and carbon nanotubes. Further, these devices are small and can be scaled aggressively.

    Research into these pressure sensors is then expanded to an exploration of graphene's gas sensing properties -- culminating in a comprehensive investigation of graphene-based humidity sensors. These sensors have rapid response and recovery times over a wide humidity range. Further, these devices can be integrated into CMOS processes back end of the line.

    In addition to CMOS Integration of these devices, a wafer scale fabrication process flow is established. Both humidity sensors and graphene-based transistors are successfully fabricated on wafer scale in a CMOS compatible process. This is an important step toward both industrialization of graphene as well as heterogeneous integration of graphene devices with diverse functionality. Furthermore, fabrication of graphene transistors on wafer scale provides a framework for the development of statistical analysis software tailored to graphene devices.

    In summary, graphene-based pressure sensors, humidity sensors, and transistors are developed for potential more than Moore applications. Further, a wafer scale fabrication process flow is established which can incorporate graphene devices into CMOS compatible process flows back end of the line.

  • 23.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Elgammal, Karim
    KTH, Centra, SeRC - Swedish e-Science Research Centre. KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Fan, Xuge
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Lemme, Max C.
    RWTH Aachen, Otto-Blumenthal-Str., 52074 Aachen, Germany .
    Delin, Anna
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Råsander, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Bergqvist, Lars
    KTH, Centra, SeRC - Swedish e-Science Research Centre. KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Schröder, Stephan
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik. SenseAir AB, Sweden..
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik. Karlsruhe Institute of Technology (KIT), Germany..
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Graphene-based CO2 sensing and its cross-sensitivity with humidity2017Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 36, s. 22329-22339Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present graphene-based CO2 sensing and analyze its cross-sensitivity with humidity. In order to assess the selectivity of graphene-based gas sensing to various gases, measurements are performed in argon (Ar), nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and air by selectively venting the desired gas from compressed gas bottles into an evacuated vacuum chamber. The sensors provide a direct electrical readout in response to changes in high concentrations, from these bottles, of CO2, O2, nitrogen and argon, as well as changes in humidity from venting atmospheric air. From the signal response to each gas species, the relative graphene sensitivity to each gas is extracted as a relationship between the percentage-change in graphene's resistance response to changes in vacuum chamber pressure. Although there is virtually no response from O2, N2 and Ar, there is a sizeable cross-sensitivity between CO2 and humidity occurring at high CO2 concentrations. However, under atmospheric concentrations of CO2, this cross-sensitivity effect is negligible – allowing for the use of graphene-based humidity sensing in atmospheric environments. Finally, charge density difference calculations, computed using density functional theory (DFT) are presented in order to illustrate the bonding of CO2 and water molecules on graphene and the alterations of the graphene electronic structure due to the interactions with the substrate and the molecules.

  • 24.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Elgammal, Karim
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Fan, Xuge
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Lemme, Max
    Delin, Anna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, SeRC - Swedish e-Science Research Centre. Uppsala Univ, Sweden.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toward Effective Passivation of Graphene to Humidity Sensing Effects2016Ingår i: 2016 46TH EUROPEAN SOLID-STATE DEVICE RESEARCH CONFERENCE (ESSDERC), IEEE, 2016, s. 299-302Konferensbidrag (Refereegranskat)
    Abstract [en]

    Graphene has a number of remarkable properties which make it well suited for both transistor devices as well as for sensor devices such as humidity sensors. Previously, the humidity sensing properties of monolayer graphene on SiO2 substrates were examined - showing rapid response and recovery over a large humidity range. Further, the devices were fabricated in a CMOS compatible process which can be incorporated back end of the line (BEOL). We now present a way to selectively passivate graphene to suppress this humidity sensing effect. In this work, we experimentally and theoretically demonstrate effective passivation of graphene to humidity sensing - allowing for future integration with other passivated graphene devices on the same chip.

  • 25.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Elgammal, Karim
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Delin, Anna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Forsberg, Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Råsander, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. Univ London Imperial Coll Sci Technol & Med, Dept Mat, England.
    Hugosson, Håkan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Bergqvist, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Schröder, Stephan
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Kataria, Satender
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. Univ Siegen, D-57076 Siegen, Germany.
    Resistive graphene humidity sensors with rapid and direct electrical readout2015Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, nr 45, s. 19099-19109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N-2), oxygen (O-2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further investigate the sensitivity of the graphene devices towards water vapor. The interaction between the electrostatic dipole moment of the water and the impurity bands in the SiO(2)d substrate leads to electrostatic doping of the graphene layer. The proposed graphene sensor provides rapid response direct electrical readout and is compatible with back end of the line (BEOL) integration on top of CMOS-based integrated circuits.

  • 26.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Sterner, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Forsberg, Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Schröder, Stephan
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    Universitat Siegen, Siegen, Germany .
    Biaxial strain in suspended graphene membranes for piezoresistive sensing2014Ingår i: 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2014, s. 1055-1058Konferensbidrag (Refereegranskat)
    Abstract [en]

    Pressure sensors based on suspended graphene membranes have shown extraordinary sensitivity for uniaxial strains, which originates from graphene's unique electrical and mechanical properties and thinness [1]. This work compares through both theory and experiment the effect of cavity shape and size on the sensitivity of piezoresistive pressure sensors based on suspended graphene membranes. Further, the paper analyzes the effect of both biaxial and uniaxial strain on the membranes. Previous studies examined uniaxial strain through the fabrication of long, rectangular cavities. The present work uses circular cavities of varying sizes in order to obtain data from biaxially strained graphene membranes.

  • 27.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Delin, Anna
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Strain engineering in suspended graphene devices for pressure sensor applications2012Ingår i: 2012 13th International Conference on Ultimate Integration on Silicon, ULIS 2012, IEEE , 2012, s. 21-24Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present paper describes a device structure for controlling and measuring strain in graphene membranes. We propose to induce strain by creating a pressure difference between the inside and the outside of a cavity covered with a graphene membrane. The combination of tight-binding calculations and a COMSOL model predicts strain induced band gaps in graphene for certain conditions and provides a guideline for potential device layouts. Raman spectroscopy on fabricated devices indicates the feasibility of this approach. Ultimately, pressure-induced band structure changes could be detected electrically, suggesting an application as ultra-sensitive pressure sensors.

  • 28.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Sterner, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Delin, Anna
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Pressure sensors based on suspended graphene membranes2013Ingår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 88, s. 89-94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel pressure sensor based on a suspended graphene membrane is proposed. The sensing mechanism is explained based on tight binding calculations of strain-induced changes in the band structure. A CMOS compatible fabrication process is proposed and used to fabricate prototypes. Electrical measurement data demonstrates the feasibility of the approach, which has the advantage of not requiring a separate strain gauge, i.e. the strain gauge is integral part of the pressure sensor membrane. Hence, graphene membrane based pressure sensors can in principle be scaled quite aggressively in size.

  • 29.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. University of Siegen, Germany.
    Large scale integration of graphene transistors for potential applications in the back end of the line2015Ingår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 108, s. 61-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A chip to wafer scale, CMOS compatible method of graphene device fabrication has been established, which can be integrated into the back end of the line (BEOL) of conventional semiconductor process flows. In this paper, we present experimental results of graphene field effect transistors (GFETs) which were fabricated using this wafer scalable method. The carrier mobilities in these transistors reach up to several hundred cm(2) V-1 s(-1). Further, these devices exhibit current saturation regions similar to graphene devices fabricated using mechanical exfoliation. The overall performance of the GFETs can not yet compete with record values reported for devices based on mechanically exfoliated material. Nevertheless, this large scale approach is an important step towards reliability and variability studies as well as optimization of device aspects such as electrical contacts and dielectric interfaces with statistically relevant numbers of devices. It is also an important milestone towards introduting graphene into wafer scale process lines.

  • 30.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Wagner, Stefan
    Kataria, Satender
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Lemme, Max C.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Wafer-Scale Statistical Analysis of Graphene FETs-Part I: Wafer-Scale Fabrication and Yield Analysis2017Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 64, nr 9, s. 3919-3926Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wafer-scale, CMOS compatible graphene transfer has been established for device fabrication and can be integrated into a conventional CMOS process flow back end of the line. In Part I of this paper, statistical analysis of graphene FET (GFET) devices fabricated on wafer scale is presented. Device yield is approximately 75% (for 4500 devices) measured in terms of the quality of the top gate, oxide layer, and graphene channel. Statistical evaluation of the device yield reveals that device failure occurs primarily during the graphene transfer step. In Part II of this paper, device statistics are further examined to reveal the primary mechanism behind device failure. The analysis from Part II suggests that significant improvements to device yield, variability, and performance can be achieved through mitigation of compressive strain introduced in the graphene layer during the graphene transfer process. The combined analyses from Parts I and II present an overview of mechanisms influencing GFET behavior as well as device yield. These mechanisms include residues on the graphene surface, tears, cracks, contact resistance at the graphene/metal interface, gate leakage as well as the effects of postprocessing.

  • 31.
    Smith, Anderson D.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Wagner, Stefan
    Kataria, Satender
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Lemme, Max C.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Wafer-Scale Statistical Analysis of Graphene Field-Effect Transistors-Part II: Analysis of Device Properties2017Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 64, nr 9, s. 3927-3933Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Part I, we have established a wafer-scale, CMOS compatible graphene transfer for the back end of the line integration. In Part II of this paper, we analyze statistical data of device properties and draw conclusions about possible causes of device failure. Statistical analysis is performed for device mobility and compared with the yield analysis. To complement this analysis, detailed Raman spectra are employed to analyze strain. In addition, device models developed in Part I are examined and provide further insight. From the analysis, it appears that compressive strain introduced during the graphene transfer process is may be the primary source for device failure. Moreover, we speculate based on the device statistics that the mitigation of compressive strain will improve device mobility, carrier density, and reduce variability. In addition, the presence of residues, tears, and cracks in the graphene may result in some device failure.

  • 32.
    Smith, Anderson David
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Paussa, Alan
    Schröder, Stephan
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Sterner, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Wagner, Stefan
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Forsberg, Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Esseni, David
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Piezoresistive Properties of Suspended Graphene Membranes under Uniaxial and Biaxial Strain in Nanoelectromechanical Pressure Sensors2016Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, nr 11, s. 9879-9886Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene membranes act as highly sensitive transducers in nanoelectromechanical devices due to their ultimate thinness. Previously, the piezoresistive effect has been experimentally verified in graphene using uniaxial strain in graphene. Here, we report experimental and theoretical data on the uni- and biaxial piezoresistive properties of suspended graphene membranes applied to piezoresistive pressure sensors. A detailed model that utilizes a linearized Boltzman transport equation describes accurately the charge-carrier density and mobility in strained graphene and, hence, the gauge factor. The gauge factor is found to be practically independent of the doping concentration and crystallographic orientation of the graphene films. These investigations provide deeper insight into the piezoresistive behavior of graphene membranes.

  • 33.
    Smith, Anderson David
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Forsberg, Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Schroder, Stephan
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Ostling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, M. C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Graphene-based piezoresistive pressure sensing for uniaxial and biaxial strains2014Ingår i: 2014 Silicon Nanoelectronics Workshop, SNW 2014, Institute of Electrical and Electronics Engineers (IEEE), 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The piezoresistive effect in graphene has been experimentally demonstrated for both uniaxial and biaxial strains. For uniaxial strain, rectangular membranes were measured while circular membranes provided biaxial strain. Gauge factors have also been extracted and compared to previous literature as well as simulations.

  • 34.
    Smith, Anderson
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Paussa, A.
    DIEGM, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Sterner, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Forsberg, Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Delin, Anna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Esseni, D.
    DIEGM, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
    Palestri, P.
    DIEGM, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. University of Siegen, Hölderlinstrasse 3, 57076 Siegen, Germany.
    Electromechanical Piezoresistive Sensing in Suspended Graphene Membranes2013Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 13, nr 7, s. 3237-3242Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monolayer graphene exhibits exceptional electronic and mechanical properties, making it a very promising material for nanoelectromechanical devices. Here, we conclusively demonstrate the piezoresistive effect in graphene in a nanoelectromechanical membrane configuration that provides direct electrical readout of pressure to strain transduction. This makes it highly relevant for an important class of nanoelectromechanical system (NEMS) transducers. This demonstration is consistent with our simulations and previously reported gauge factors and simulation values. The membrane in our experiment acts as a strain gauge independent of crystallographic orientation and allows for aggressive size scalability. When compared with conventional pressure sensors, the sensors have orders of magnitude higher sensitivity per unit area.

  • 35.
    Smith, Anderson
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, M. C.
    Wafer Scale Graphene Transfer for Back End of the Line Device Integration2014Ingår i: INT CONF ULTI INTEGR, ISSN 2330-5738, s. 29-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a wafer scale fabrication of graphene based field effect transistors (GFETs) for use in future radio frequency (RF) and sensor applications. The process is also almost entirely CMOS compatible and uses a scalable graphene transfer method that can be incorporated in standard CMOS back end of the line (BEOL) process flows. Such a process can be used to integrate high speed GFET devices and graphene sensors with silicon CMOS circuits.

  • 36.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Belete, M.
    Dentoni Litta, Eugenio
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, G.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. University of Siegen, Germany.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Bilayer insulator tunnel barriers for graphene-based vertical hot-electron transistors2015Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, nr 30, s. 13096-13104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vertical graphene-based device concepts that rely on quantum mechanical tunneling are intensely being discussed in the literature for applications in electronics and optoelectronics. In this work, the carrier transport mechanisms in semiconductor-insulator-graphene (SIG) capacitors are investigated with respect to their suitability as electron emitters in vertical graphene base transistors (GBTs). Several dielectric materials as tunnel barriers are compared, including dielectric double layers. Using bilayer dielectrics, we experimentally demonstrate significant improvements in the electron injection current by promoting Fowler-Nordheim tunneling (FNT) and step tunneling (ST) while suppressing defect mediated carrier transport. High injected tunneling current densities approaching 103 A cm(-2) (limited by series resistance), and excellent current-voltage nonlinearity and asymmetry are achieved using a 1 nm thick high quality dielectric, thulium silicate (TmSiO), as the first insulator layer, and titanium dioxide (TiO2) as a high electron affinity second layer insulator. We also confirm the feasibility and effectiveness of our approach in a full GBT structure which shows dramatic improvement in the collector on-state current density with respect to the previously reported GBTs. The device design and the fabrication scheme have been selected with future CMOS process compatibility in mind. This work proposes a bilayer tunnel barrier approach as a promising candidate to be used in high performance vertical graphene-based tunneling devices.

  • 37.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Belete, M.
    Smith, Anderson David
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dentoni Litta, Eugenio
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, G.
    Lemme, Max
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Step tunneling-enhanced hot-electron injection in vertical graphene base transistors2015Ingår i: European Solid-State Device Research Conference, Editions Frontieres , 2015, s. 198-201Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents promising current-voltage characteristics of semiconductor-insulator-graphene tunnel diodes as the hot-electron injection unit in graphene base transistors (GBTs). We propose that by using a bilayer tunnel barrier one can effectively suppress the defect mediated carrier transport while enhancing the hot-electron emission through Fowler-Nordheim tunneling (FNT) and step tunneling (ST). A stack of TmSiO/TiO2 (1 nm/ 5.5 nm) is sandwiched between a highly doped Si substrate and a single layer graphene (SLG) as the electrodes. This tunnel diode exhibits high current with large nonlinearity suitable for the application in GBTs.

  • 38.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, G.
    Smith, Anderson
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dabrowski, J.
    Lippert, G.
    Mehr, W.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Graphene base hot electron transistors with high on/off current ratios2013Ingår i: Dev. Res. Conf. Conf. Dig., IEEE conference proceedings, 2013, s. 39-40Konferensbidrag (Refereegranskat)
    Abstract [en]

    Despite exceptional intrinsic properties of graphene, field effect transistors with graphene channels (GFETs) are limited by the absence of an electronic band gap. The resulting low ION-IOFF ratio and low output resistance makes GFETs unsuitable for logic applications [1] and limits radio frequency (RF) applications [2]. We will present a graphene-based electronic device in which the 0 eV band gap does not limit the device performance: a hot electron transistor (HET) with a graphene base (Graphene Base Transistor, GBT) [3,4]. The single-atomic thinness and high conductivity are decisive advantages of a graphene base [5]. Here, we report on the fabrication and full DC-characterization of GBTs with high ION-IOFF ratio of 105.

  • 39.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, Grzegorz
    Henkel, Christoph
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dabrowski, Jarek
    Lippert, Gunther
    Mehr, Wolfgang
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A Graphene-Based Hot Electron Transistor2013Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 13, nr 4, s. 1435-1439Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We experimentally demonstrate DC functionality of graphene-based hot electron transistors, which we call graphene base transistors (GBT). The fabrication scheme is potentially compatible with silicon technology and can be carried out at the wafer scale with standard silicon technology. The state of the GBTs can be switched by a potential applied to the transistor base, which is made of graphene. Transfer characteristics of the GBTs show ON/OFF current ratios exceeding 10(4).

  • 40.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, Grzegorz
    Paussa, Alan
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Henkel, Christoph
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lippert, Gunther
    Dabrowski, Jarek
    Mehr, Wolfgang
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A manufacturable process integration approach for graphene devices2013Ingår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 84, s. 185-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we propose an integration approach for double gate graphene field effect transistors. The approach includes a number of process steps that are key for future integration of graphene in microelectronics: bottom gates with ultra-thin (2 nm) high-quality thermally grown SiO2 dielectrics, shallow trench isolation between devices and atomic layer deposited Al2O3 top gate dielectrics. The complete process flow is demonstrated with fully functional GFET transistors and can be extended to wafer scale processing. We assess, through simulation, the effects of the quantum capacitance and band bending in the silicon substrate on the effective electric fields in the top and bottom gate oxide. The proposed process technology is suitable for other graphene-based devices such as graphene-based hot electron transistors and photodetectors.

  • 41.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Henkel, Christoph
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, G.
    Lippert, G.
    Dabrowski, J.
    Mehr, W.
    An integration approach for graphene double-gate transistors2012Ingår i: Solid-State Device Research Conference (ESSDERC), 2012 Proceedings of the European, IEEE , 2012, s. 250-253Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we propose an integration approach for double gate graphene field effect transistors. The approach includes a number of process steps that are key for microelectronics integration: bottom gates with ultra-thin (2nm) high-quality thermally grown SiO2 dielectrics, shallow trench isolation between devices and atomic layer deposited Al2O3 top gate dielectrics. The complete process flow is demonstrated with fully functional GFET transistors and can be extended to wafer scale processing and other graphene-based devices.

  • 42.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson David
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, G.
    Dabrowski, J.
    Lippert, G.
    Mehr, W.
    Driussi, F.
    Venica, S.
    Di Lecce, V.
    Gnudi, A.
    Koenig, M.
    Ruhl, G.
    Belete, M.
    Lemme, M. C.
    Going ballistic: Graphene hot electron transistors2015Ingår i: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 224, s. 64-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reviews the experimental and theoretical state of the art in ballistic hot electron transistors that utilize two-dimensional base contacts made from graphene, i.e. graphene base transistors (GBTs). Early performance predictions that indicated potential for THz operation still hold true today, even with improved models that take non-idealities into account. Experimental results clearly demonstrate the basic functionality, with on/off current switching over several orders of magnitude, but further developments are required to exploit the full potential of the GBT device family. In particular, interfaces between graphene and semiconductors or dielectrics are far from perfect and thus limit experimental device integrity, reliability and performance.

  • 43.
    Vaziri, Sam
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lupina, G.
    Lemme, Max
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    PDMS-supported Graphene Transfer Using Intermediary Polymer Layers2014Ingår i: PROCEEDINGS OF THE 2014 44TH EUROPEAN SOLID-STATE DEVICE RESEARCH CONFERENCE (ESSDERC 2014), IEEE, 2014, s. 309-312Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a graphene transfer method based on chemical vapor deposited (CVD) graphene grown on copper foils. This transfer method utilizes a combination of a silicone elastomer (PDMS) and different intermediate polymer layers depending on the process requirements. We use polystyrene and polystyrene/photoresist intermediary layers for dry and wet graphene release. PMMA intermediary layer is applied for bubbling-assisted graphene transfer. The elastomer layer serves as an excellent solid support for electrochemical graphene delamination. Graphene-based field effect transistors (GFETs) were fabricated and characterized using this process. Raman spectroscopy was used in order to verify a successful

  • 44. Wagner, S.
    et al.
    Weisenstein, C.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kataria, S.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. University of Siegen, Germany.
    Graphene transfer methods for the fabrication of membrane-based NEMS devices2016Ingår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 159, s. 108-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane based nanoelectromechanical systems (NEMS). Here, three methods for direct transfer of chemical vapor deposited graphene onto pre-fabricated micro cavity substrates were investigated and analyzed with respect to yield and quality of the free-standing membranes on a large-scale. An effective transfer method for layer-by-layer stacking of graphene was developed to improve the membrane stability and thereby increase the yield of completely covered and sealed cavities. The transfer method with the highest yield was used to fabricate graphene NEMS devices. Electrical measurements were carried out to successfully demonstrate pressure sensing as a possible application for these graphene membranes.

  • 45. Wagner, Stefan
    et al.
    Dieing, Thomas
    Centeno, Alba
    Zurutuza, Amaia
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Ostling, Mikael
    Kataria, Satender
    Lemme, Max C.
    Noninvasive Scanning Raman Spectroscopy and Tomography for Graphene Membrane Characterization2017Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, nr 3, s. 1504-1511Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane based nanoelectromechanical systems (NEMS). Here, chemical-vapor-deposited graphene is transferred onto target substrates to suspend it over cavities and trenches for pressure-sensor applications. The development of such devices requires suitable metrology methods, i.e., large-scale characterization techniques, to confirm and analyze successful graphene transfer with intact suspended graphene membranes. We propose fast and noninvasive Raman spectroscopy mapping to distinguish between freestanding and substrate-supported graphene, utilizing the different strain and doping levels. The technique is expanded to combine two-dimensional area scans with cross-sectional Raman spectroscopy, resulting in three-dimensional Raman tomography of membrane-based graphene NEMS. The potential of Raman tomography for in-line monitoring is further demonstrated with a methodology for automated data analysis to spatially resolve the material composition in micrometer-scale integrated devices, including free-standing and substrate-supported graphene. Raman tomography may be applied to devices composed of other two-dimensional materials as well as silicon micro- and nanoelectromechanical systems.

  • 46.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Smith, Anderson
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Delekta, Szymon Sollami
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. Siegen University, Germany.
    Emerging graphene device technologies2016Ingår i: Emerging Nanomaterials and Devices, Electrochemical Society, 2016, Vol. 75, nr 13, s. 17-35, artikel-id 13Konferensbidrag (Refereegranskat)
    Abstract [en]

    Graphene has a wide range of attractive electrical and mechanical properties. This unique blend of properties make it a good candidate for emerging and future device technologies, such as sensors, high frequency electronics, and energy storage devices. In this review paper, each of the aforementioned applications will be explored along with demonstrations of their operating principles. Specifically, we explore pressure and humidity sensors, graphene base transistor for high frequency applications, and supercapacitors. In addition, this paper provides a general overview of these graphene technologies and, in the case of pressure and humidity sensors, benchmarking against other competing technologies. This paper further shows possible and prospective paths that are suitable for future graphene research to take.

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