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  • 1. Akram, Muhammad Nadeem
    et al.
    Xiang, Yu
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Yu, Xingang
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zabel, Thomas
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Influence of base-region thickness on the performance of Pnp transistor-VCSEL2014In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 22, no 22, p. 27398-27414Article in journal (Refereed)
    Abstract [en]

    We have recently reported a 980nm GaAs-based three terminal Pnp transistor-vertical-cavity surface-emitting laser (TVCSEL) operating at room temperature with optical power up to 1.8mW. However, the current gain beta = Delta I-c/Delta I-b was near zero just before lasing and became negative after the lasing threshold. The main cause of the negative current gain was found to be a gradual and position-dependent forward-biasing (saturation) of the base-collector junction with increasing bias even before lasing threshold. In this article, detailed multi-physics device simulations are performed to better understand the device physics, and find ways to avoid the premature saturation of the base-collector junction. We have optimized the thickness of the base region as well as its doping concentration and the location of the quantum wells to ensure that the T-VCSEL is in the active mode throughout its range of operation. That is, the emitter-base junction is forward biased and base-collector junction is reversed biased for sweeping the excess charges out of the base region.

  • 2. Andersson, J. Y.
    et al.
    Hoglund, L.
    Noharet, B.
    Wang, Q.
    Ericsson, P.
    Wissmar, Stanley
    Asplund, C.
    Malm, H.
    Martijn, H.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Gustafsson, Oscar
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hellström, S.
    Radamson, Henry
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Holtz, P. O.
    Quantum structure based infrared detector research and development within Acreo's centre of excellence IMAGIC2010In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 53, no 4, p. 227-230Article in journal (Refereed)
    Abstract [en]

    Acreo has a long tradition of working with quantum structure based infrared (IR) detectors and arrays. This includes QWIP (quantum well infrared photodetector), QDIP (quantum dot infrared photodetector), and InAs/GaInSb based photon detectors of different structure and composition. It also covers R&D on uncooled microbolometers. The integrated thermistor material of such detectors is advantageously based on quantum structures that are optimised for high temperature coefficient and low noise. Especially the SiGe material system is preferred due to the compatibility with silicon technology. The R&D work on IR detectors is a prominent part of Acreo's centre of excellence "IMAGIC" on imaging detectors and systems for non-visible wavelengths. IMAGIC is a collaboration between Acreo, several industry partners and universities like the Royal Institute of Technology (KTH) and Linkoping University. (C) 2010 Elsevier B.V. All rights reserved.

  • 3. Asplund, C.
    et al.
    Mogg, S.
    Plaine, G.
    Salomonsson, F.
    Chitica, N.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Doping-induced losses in AlAs/GaAs distributed Bragg reflectors2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 90, no 2, p. 794-800Article in journal (Refereed)
    Abstract [en]

    We have studied n- and p-type doping-induced performance degradation of AlAs/GaAs distributed Bragg reflectors (DBRs) for applications in vertical cavity lasers (VCLs). Based on high-accuracy optical reflectance and triple-axis x-ray diffraction measurements on a variety of differently doped DBR structures grown by metalorganic vapor-phase epitaxy, a fitting procedure was employed to extract the doping-dependent optical loss. A striking observation is that the reflectance of these DBRs is much more sensitive to n- than p-type doping incorporation. While in the latter case the loss can be well accounted for by intervalence-band and free-carrier absorption, additional loss mechanisms must be considered for n-type DBRs. We relate the losses to doping-enhanced interdiffusion effects resulting in increased interface scattering. These findings should have important consequences for the design of VCLs, demonstrating the importance of reduced n-type doping concentrations and/or growth temperatures, or the application of alternative device concepts, e.g., employing intracavity contacts.

  • 4.
    Asplund, Carl
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Optimization of MOVPE-grown GaInNAs/GaAs quantum wells for 1.3-μm laser applications2002Conference paper (Refereed)
    Abstract [en]

    The effects of high group-V precursor flows during metal-organic vapor phase epitaxial growthof GaInNAs QWs are investigated. It is shown that photoluminescence line width, waferuniformity, and sensitivity to growth temperature can be improved using V/III ratios in excess of2000. Broad area GaInNAdGaAs SQW lasers with dimensions 100 x 820 pm2 grown under theseconditions have threshold current densities as low as 660 kA/cm2 at 1.26 pm emission wavelength.

  • 5.
    Asplund, Carl
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mogg, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Christiansson, Ulf
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Oscarsson, V.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Runnström, C.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Odling, E.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Malmquist, J.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    1260 nm InGaAs vertical-cavity lasers2002In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 38, no 13, p. 635-636Article in journal (Refereed)
    Abstract [en]

     The fabrication and performance of highly strained double-quantum well InGaAs/GaAs vertical-cavity lasers with record-long emission wavelength of 1260 nm at room temperature is reported. Depending on device diameter, the minimum threshold current is in the low mA-regime while the maximum output power exceeds 1 mW. The devices work continuous-wave over a wide temperature range of at least 10-120degrees C.

  • 6.
    Atwa, Mohamed M.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Alaskalany, Ahmed
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Elgammal, Karim
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Smith, Anderson D.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Trilayer Graphene as a Candidate Material for Phase-Change Memory Applications2016In: MRS Advances, ISSN 2316-7858, E-ISSN 1610-191X, Vol. 1, no 20, p. 1487-1494Article in journal (Refereed)
    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.

  • 7. Baranowski, M.
    et al.
    Kudrawiec, R.
    Misiewicz, J.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Nitrogen-related changes in exciton localization and dynamics in GaInNAs/GaAs quantum wells grown by metalorganic vapor phase epitaxy2015In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 118, no 2, p. 479-486Article in journal (Refereed)
    Abstract [en]

    In this work, we show the results of low-temperature photoluminescence (PL), time-resolved photoluminescence, and photoreflectance (PR) investigations, performed on a series of three Ga0.64In0.34As1-x N (x) /GaAs single quantum wells (SQW) grown by metalorganic vapor phase epitaxy with the nitrogen content of 0, 0.5, and 0.8 %. Comparing the PL and PR data, we show that at low excitation intensity and temperature, the radiative recombination occurs via localizing centers (LCs) in all samples. The excitation intensity-dependent PL measurements combined with theoretical modeling of hopping excitons in this system allow us to provide quantitative information on the disorder parameters describing population of LCs. It has been found that the average energy of LCs increases about two times and simultaneously the number of LCs increases about 10 and 20 times after the incorporation of 0.5 and 0.8 % of nitrogen, respectively. The value of average localization energy E > (0) determined for N-containing samples (similar to 6-7 meV) is in the range typical for dilute nitride QWs grown by molecular beam epitaxy (MBE). On the other hand, the "effective" concentration of LCs seems to be higher than for GaInNAs/GaAs QW grown by MBE. The dramatic increase in localizing centers also affects the PL dynamics. Observed PL decay time dispersion is much stronger in GaInNAs SQW than in nitrogen-free SQW. The change in PL dynamic is very well reproduced by model of hopping excitons.

  • 8. Bentell, J.
    et al.
    Wennekes, F.
    Salomonsson, F.
    Hammar, M.
    Streubel, K.
    Characterisation of n-InP/n-GaAs Wafer Fused Heterojunctions1999In: Physica scripta. T, ISSN 0281-1847, Vol. 79, p. 206-208Article in journal (Refereed)
    Abstract [en]

    We have investigated the properties of wafer-fused Si-doped isotype hetero-junctions between GaAs and InP. Current/voltage measurements were conducted to study the influence of the doping concentrations on each side of the interface on the electrical conductivity. An almost ohmic behavior with a very low series resistance was obtained for the highest examined doping level on the GaAs side, whereas the doping concentration on the InP side was found to be of little significance. Fusion at different temperatures showed that the conductivity degrades significantly below 500°C, although mechanically stable junctions were obtained also at temperatures as low as 305°C. Secondary ion mass spectroscopy measurements showed no redistribution of Si, but indicated the presence of small amounts of C and Fe impurities at the interface.

  • 9. Bernabé, S.
    et al.
    Stevens, R.
    Volpert, M.
    Hamelin, R.
    Rossat, C.
    Berger, F.
    Lombard, L.
    Kopp, C.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Highly integrated VCSEL-based 10Gb/s miniature optical sub-assembly2005In: Proceedings - Electronic Components and Technology Conference, Lake Buena Vista, FL: IEEE , 2005, Vol. 2, p. 1333-1338Conference paper (Refereed)
    Abstract [en]

    In order to fit with the present and future needs of the Datacom transceiver market, newly designed high rate transmitter optical subassemblies (TOSAs) have to be compact, low cost and compatible with mass production. We propose here an innovative design strategy that reaches all these targets by integrating a 10Gbps 850nmVCSEL laser diode and its laser driver with other functionalities (e.g. power monitoring and thermal monitoring) in a small form factor package. Taking advantages of the optical properties of the VCSEL and using flip-chip techniques, the transmitter exhibits excellent hyperfrequency performances and compatibility with mass production due to the use of collective manufacturing technologies and passive optical alignment. This versatile approach is also applicable to high rate receivers, parallel optics emitters, and singlemode low cost transmitter integrating long wavelength VCSELs.

  • 10.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Sundgren, Petrus
    Marcks von Würtemberg, Rikard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    1.3 um InGaAs VCSELs: Influence of the Large Gain-Cavity Detuning on the Modulation and Static Performance2004In: Proc. of 30th European Conference on Optical Communication 2004, 2004Conference paper (Refereed)
  • 11.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Marcks von Würtemberg, Rickard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Mogg, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Single-mode 1.27 μm InGaAs vertical cavity surface-emitting lasers with temperature-tolerant modulation characteristics2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 21, p. 211109-1-211109-3Article in journal (Refereed)
    Abstract [en]

    The dynamic performance of InGaAs/GaAs 1.27 μ m single-mode vertical cavity surface emitting lasers (VCSELs) is presented. In order to reach such a long wavelength, the devices utilize highly strained double-quantum wells and a large detuning between the material gain peak and cavity resonance. It is found that the large detuning improves the temperature stability of both static and modulation characteristics. A resonance frequency of 7.8-9.5 GHz and optical power of 0.30 mW in fiber was maintained throughout the investigated temperature range of 20-90 ° C. The intrinsic response of the device suggests that long-wavelength InGaAs/GaAs VCSELs have the potential to be used as low cost uncooled optical transmitters at 10 Gbit/s. © 2005 American Institute of Physics. © 2005 American Institute of Physics.

  • 12.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Berggren, Jesper
    Yu, X.
    KTH.
    Marcks Von Würtemberg, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Dynamic properties of electrically p-n confined, epitaxially regrown 1.27 μm InGaAs single-mode vertical-cavity surface-emitting lasers2009In: IET optoelectronics, ISSN 1751-8768, Vol. 3, no 3, p. 163-167Article in journal (Refereed)
    Abstract [en]

    The dynamic performance including chirp measurements of 1.27 mu m single-mode InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a large gain-cavity offset is presented. The VCSELs are based on a novel p-n confinement structure with selective area epitaxial regrowth. A resonance frequency of 9.11 GHz, a slope efficiency of 0.25 W/A and an alpha-factor of 5.7 were measured. The modulation bandwidth is limited by electrical parasitics. Eye diagrams at 5 Gb/s with 7 dB extinction ratio and Q-factor around 5 were obtained. The results are compared with the performance of oxide-confined VCSELs with similar active layer and negative gain-cavity detuning.

  • 13. Chang, Tzu-Hsuan
    et al.
    Fan, Wenjuan
    Liu, Dong
    Xia, Zhenyang
    Ma, Zhenqiang
    Liu, Shihchia
    Menon, Laxmy
    Yang, Hongjun
    Zhou, Weidong
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT).
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Selective release of InP heterostructures from InP substrates2016In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 34, no 4, article id 041229Article in journal (Refereed)
    Abstract [en]

    The authors report here a method of protecting the sidewall for the selective release of InGaAsP quantum-well (QW) heterostructure from InP substrates. An intact sidewall secured by SiO2 was demonstrated during the sacrificial layer selective etching, resulting in the suspended InGaAsP QW membranes which were later transferred to the Si substrate with polydimethylsiloxane stamp. The quality of the transferred InGaAsP QW membranes has been validated through photoluminescence and EL measurements. This approach could extend to arbitrary targeting substrate in numerous photonics and electronics applications.

  • 14. Fan, W.
    et al.
    Zhao, D.
    Chuwongin, S.
    Seo, J. -H
    Yang, H.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Ma, Z.
    Zhou, W.
    Electrically-pumped membrane-reflector surface-emitters on silicon2013In: 2013 IEEE Photonics Society Summer Topical Meeting Series, PSSTMS 2013, IEEE , 2013, p. 19-20Conference paper (Refereed)
    Abstract [en]

    We report here electrically-pumped membrane reflector surface-emitters on silicon based on transferred InGaAsP QW structures sandwiched in between two single-layer Fano resonance photonic crystal membrane reflectors on silicon substrate.

  • 15. Fan, W.
    et al.
    Zhao, D.
    Chuwongin, S.
    Seo, J. -H
    Yang, H.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Ma, Z.
    Zhou, W.
    Fabrication of electrically-pumped resonance-cavity membrane-reflector surface-emitters on silicon2013In: 2013 IEEE Photonics Conference (IPC), 2013, p. 643-644Conference paper (Refereed)
    Abstract [en]

    Various lasers and light sources on Si via heterogeneous integration of Si/III-V have been reported based on direct growth on Si [1] or wafer bonding technology [2-4]. We reported earlier optically-pumped Si membrane-reflector vertical-cavity surface-emitting lasers (MRVCSELs) fabricated by low-temperature membrane transfer printing processes [5, 6]. Here we report electrically-pumped devices based on an intra-cavity contact configuration.

  • 16. Gholami, M.
    et al.
    Esmaeili, M.
    Haratizadeh, H.
    Holtz, P. O.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Evaluation of optical quality and properties of Ga0.64In0.36N0.006As0.994 lattice matched to GaAs by using photoluminescence spectroscopy2009In: Opto-Electronics Review, ISSN 1230-3402, E-ISSN 1896-3757, Vol. 17, no 3, p. 260-264Article in journal (Refereed)
    Abstract [en]

    We have investigated optical properties of Ga0.64In0.36N0.006As0.994/GaAs single quantum-well structures using photoluminescence technique. We have found that nitrogen creates potential fluctuations in the InGaNAs structures, so it is the cause of trap centres in these structures and leads to localized excitons recombination dynamics. The near-band edge PL at 2 K exhibited a blueshift with an increase in excitation intensity of a sample but there is not such a shift in the PL peak position energy of same sample at 150 K. It has been found that PL spectra have a large full width at half maximum (FWHM) value at 2 K. These results are discussed in terms of carrier localization. Additionally, our results suggest decreasing PL integrated intensity in this structure, possibly due to non-radiative recombination. It has been shown that thermal annealing reduces the local strain created by nitrogen. By annealing process, a blue shifted emission can be observed.

  • 17. Gholami, M.
    et al.
    Haratizadeh, H.
    Esmaeili, M.
    Amiri, R.
    Holtz, P. O.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Alternation of band gap and localization of excitons in InGaNAs nanostructures with low nitrogen content2008In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 19, no 31Article in journal (Refereed)
    Abstract [en]

    Continuous wave photoluminescence (cw PL) spectroscopy has been used to study the optical properties of a set of InGaNAs epilayers and single quantum wells with nitrogen concentration less than a few per cent at different temperatures and different excitation powers. We found that nitrogen has a critical role on the emission light of InGaNAs nanostructures and the recombination mechanism. The incorporation of a few per cent of nitrogen leads to shrinkage of the InGaNAs band gap. The physical origin of such band gap reduction has been investigated both experimentally and theoretically by using a band anticrossing model. We have found that localization of excitons that have been caused by incorporation of a few per cent of nitrogen in these structures is the main explanation of such anomalous behavior observed in the low-temperature photoluminescence spectra of these nanostructures. The localization energies of carriers have been evaluated by studying the variation of the quantum well (QW) emission versus temperature, and it was found that the localization energy increases with increasing nitrogen composition. Our data also show that, with increasing excitation intensity, the PL peak position moves to higher energies (blue shift) due to the filling of localized states and capture centers for excitons by photo-generated carriers.

  • 18. Gilet, Ph.
    et al.
    Pougeoise, E.
    Grenouillet, L.
    Grosse, Ph.
    Olivier, N.
    Poncet, S.
    Chelnokov, A.
    Gerard, J. M.
    Stevens, R.
    Hamelin, R.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    1.3 μm VCSELs: InGaAs/GaAs, GaInNAs/GaAs multiple quantum wells and InAs/GaAs quantum dots- Three candidates as active material2007In: Vertical - Cavity Surface - Emitting Lasers XI, San Jose, CA, 2007, Vol. 6484, p. F4840-F4840Conference paper (Refereed)
    Abstract [en]

    In this article, we report our results on 1.3ÎŒm VCSELs for optical interconnection applications. Room temperature continuous-wave lasing operation is demonstrated for top emitting oxide-confined devices with three different active materials, highly strained InGaAs/GaAs(A) and GalnNAs/GaAs (B) multiple quantum wells (MQW) or InAs/GaAs (C) quantum dots (QD). Conventional epitaxial structures grown respectively by Metal Organic Vapour Phase Epitaxy (MOVPE), Molecular Beam Epitaxy (MBE) and MBE, contain rully doped GaAs/AlGaAs DBRs. All three epilayers are processed in the same way. Current and optical confinement are realized by selective wet oxidation. Circular apertures from 2 ÎŒm to 16 ÎŒm diameters are defined. At room temperature and in continuous wave operation, all three systems exhibit lasing operation at wavelengths above 1 275nm and reached 1 300nm for material (A). Typical threshold currents are in the range [1-10]mA and are strongly dependent firstly on oxide diameter and secondly on temperature. Room temperature cw maximum output power corresponds respectively to 1.77mW, 0.5mW and 0.6mW. By increasing driving current, multimode operation occurs at different level depending on the oxide diameter. In case (A), non conventional modal behaviors will be presented and explained by the presence of specific oxide modes. Thermal behaviors of the different devices have been compared. In case (A) and (C) we obtain a negative T0. We will conclude on the different active materials in terms of performances with respect to 1300nm VCSEL applications.

  • 19.
    Gustafsson, Oscar
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Höglund, L.
    Karim, A.
    Noharet, B.
    Wang, Q.
    Gromov, A.
    Almqvist, S.
    Zhang, A.
    Acreo, Sweden.
    Junique, S.
    Andersson, J. Y.
    Asplund, C.
    von Würtemberg, R. Marcks
    Malm, H.
    Martijn, H.
    Long-wavelength infrared quantum-dot based interband photodetectors2011In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 54, no 3, p. 287-291Article in journal (Refereed)
    Abstract [en]

    We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.

  • 20.
    Gustafsson, Oscar
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Höglund, L.
    Berggren, Jespe
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    GaSb/Ga0.51In0.49P self assembled quantum dots grown by MOVPE2009In: Proceedings from EW-MOVPE XIII, 2009, Vol. 7298, p. 273-276Conference paper (Refereed)
  • 21.
    Gustafsson, Oscar
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Karim, Amir
    Asplund, Carl
    Wang, Qin
    Zabel, Thomas
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Almqvist, S.
    Savage, S.
    Andersson, Jan Y.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    A performance assessment of type-II interband In0.5Ga0.5Sb QD photodetectors2013In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 61, p. 319-324Article in journal (Refereed)
    Abstract [en]

    Self-assembled quantum-dot (QD) structures with type-II band alignment to the surrounding matrix material have been proposed as a III/V material approach to realize small-bandgap device structures suitable for photon detection and imaging in the long-wavelength infrared (LWIR) band. Here, we analyze the photoresponse of In0.5Ga0.5Sb/InAs QD photodiodes and estimate the system performance of type-II QD - based photodetectors. A review of alternative design approaches is presented and the choice of matrix material is discussed in terms of band alignment and its effect on the photoresponse. Photodiodes were fabricated consisting of 10 layers of In0.5Ga0.5Sb QDs grown on InAs (0 0 1) substrates with metal-organic vapor-phase epitaxy (MOVPE). The photoresponse and dark current were measured in single pixel devices as a function of temperature in the range 20-230 K. The quantum efficiency shows an Arrhenius type behavior, which is attributed to hole trapping. This severely limits the detector performance at typical LWIR sensor operating temperatures (60-120 K). A device design with the matrix material InAs0 6Sb0 4 is proposed as a mean to improve the performance by reducing the barrier for hole transport. This can potentially allow type-II InGaSb QDs to be a competitive sensor material for LWIR detection.

  • 22.
    Gustafsson, Oscar
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Karim, Amir
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Wang, Qin
    Reuterskiöld-Hedlund, Carl
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Ernerheim-Jokumsen, Christopher
    KTH.
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Persson, Sirpa
    Almqvist, Susanne
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Noharet, Bertrand
    Asplund, Carl
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Andersson, Jan Y.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Photoluminescence and photoresponse from InSb/InAs-based quantum dot structures2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 19, p. 21264-21271Article in journal (Refereed)
    Abstract [en]

    InSb-based quantum dots grown by metal-organic vapor-phase epitaxy (MOVPE) on InAs substrates are studied for use as the active material in interband photon detectors. Long-wavelength infrared (LWIR) photoluminescence is demonstrated with peak emission at 8.5 mu m and photoresponse, interpreted to originate from type-II interband transitions in a p-i-n photodiode, was measured up to 6 mu m, both at 80 K. The possibilities and benefits of operation in the LWIR range (8-12 mu m) are discussed and the results suggest that InSb-based quantum dot structures can be suitable candidates for photon detection in the LWIR regime.

  • 23.
    Gustafsson, Oscar
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Karim, Amir
    Wang, Qin
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Asplund, Carl
    Andersson, Jan Y.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Long-wavelength infrared photoluminescence from InGaSb/InAs quantum dots2013In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 59, p. 89-92Article in journal (Refereed)
    Abstract [en]

    We study the growth of self-assembled InGaSb/InAs quantum dots (QDs) and investigate how gallium can be used to reduce the optical transition energy in the InSb QD system. InGaSb QDs were grown on InAs (0 0 1) substrates by metal-organic vapor-phase epitaxy (MOVPE) and the material was characterized by photoluminescence (PL) measurements. A PL peak wavelength is demonstrated beyond 8 μm at 77 K, which is significantly longer than what has been reported for InSb QDs. The results suggest that InGaSb QDs can be grown at a larger size than InSb QDs leading to reduced confinement in the QDs.

  • 24.
    Gyger, Samuel
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Zeuner, Katharina D.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Jöns, Klaus D.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Elshaari, Ali W.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Paul, Matthias
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Reuterskiöld Hedlund, Carl
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hammar, Mattias
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics. Rise AB, NETLAB, Isafjordsgatan 22, S-16440 Kista, Sweden.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Reconfigurable frequency coding of triggered single photons in the telecom C-band2019In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 27, no 10, p. 14400-14406Article in journal (Refereed)
    Abstract [en]

    In this work, we demonstrate reconfigurable frequency manipulation of quantum states of light in the telecom C-band. Triggered single photons are encoded in a superposition state of three channels using sidebands up to 53 GHz created by an off-the-shelf phase modulator. The single photons are emitted by an InAs/GaAs quantum dot grown by metal-organic vapor-phase epitaxy within the transparency window of the backbone fiber optical network. A cross-correlation measurement of the sidebands demonstrates the preservation of the single photon nature; an important prerequisite for future quantum technology applications using the existing telecommunication fiber network.

  • 25.
    Hammar, M.
    et al.
    KTH, Superseded Departments, Electronics.
    Rodriguez Messmer, E.
    Luzuy, M.
    Anand, S.
    Lourdudoss, S.
    Landgren, G.
    Topography dependent doping distribution in selectively regrown InP studied by scanning capacitance microscopy1998In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 72, no 7, p. 815-817Article in journal (Refereed)
    Abstract [en]

    We have used scanning capacitance microscopy (SCM) to study the dopant distribution in regrown InP with high sensitivity and spatial resolution. Sulfur or iron doped InP was selectively regrown around n-doped InP mesas using hydride vapor phase epitaxy, and the resulting structure was imaged in cross section by SCM. For calibration purposes, reference layers with known doping levels were grown directly on top of the region of interest. Dramatic variations in the carrier concentration around the mesa, as well as pronounced differences in the behavior of S and Fe are observed. We correlate these findings to the growth and doping incorporation mechanisms. © 1998 American Institute of Physics.

  • 26. Hammar, M.
    et al.
    Wennekes, F.
    Salomonsson, F.
    Bentell, J.
    Streubel, K.
    Rapp, S.
    Keiper, D.
    Westphalen, R.
    Systematics of electrical conductivity across InP to GaAs wafer-fused interfaces1999In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 38, no 2 B, p. 1111-1114Article in journal (Refereed)
    Abstract [en]

    We report on the electrical and compositional characterization of wafer-fused isotype heterojunctions between Zn-, C- or Si-doped GaAs and Zn- or Si-doped InP. The junctions were characterized by current-voltage and secondary ion mass spectrometry (SIMS) measurements. It is demonstrated that very low-resistive junctions can be obtained in each case, but also that there is a strong influence from the detailed sample structure and processing conditions. SIMS was used to monitor the doping concentration across the interface as well as the impurity concentrations of oxygen, carbon and iron. © 1999 Publication Board, Japanese Journal of Applied Physics.

  • 27.
    Hammar, Mattias
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    von Würtemberg, Rickard Marcks
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Larsson, A.
    Söderberg, E.
    Modh, P.
    Gustavsson, J.
    Ghisoni, M.
    Chitica, N.
    1.3-mu m InGaAs vertical-cavity surface-emitting lasers2005In: 2005 IEEE LEOS Annual Meeting Conference Proceedings (LEOS), 2005, p. 396-397Conference paper (Refereed)
    Abstract [en]

    We report on the fabrication and performance of N-free InGaAs/GaAs 1.3-mu m range vertical-cavity surface-emitting lasers (VCSELs). Using optimized quantum-well (QW) growth conditions in combination with negative gain-cavity tuning, high-performance VCSELs with emission wavelength up to 1300 nm are realized. The performance figures include mA-range threshold currents, mW-range singlemode output power, continuous-wave operation up to 140 degrees C and 10 Gbit/s data transmission.

  • 28.
    Hammar, Mattias
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Xiang, Yu
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Yu, Xingang
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zabel, Thomas
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Akram, M. N.
    Room-temperature operation of 980-nm transistor-vertical-cavity surface-emitting lasers2013In: 2013 IEEE 6th International Conference on Advanced Infocomm Technology, ICAIT 2013, IEEE , 2013, p. 141-142Conference paper (Refereed)
    Abstract [en]

    We report on the design, fabrication and characterization of pnp-type 980-nm transistor-vertical-cavity surface-emitting lasers (T-VCSELs). Using an epitaxial regrowth process and a triple-intracavity current injection scheme we demonstrate static performance levels quite comparable to those of conventional VCSELs, including sub-mA threshold base current, mW-range output power and continuous-wave operation at least up to 50°C.

  • 29. Iezekiel, S.
    et al.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Transistor lasers and their expected applications in microwave photonics2015In: 2015 17th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2015, article id 7193352Conference paper (Refereed)
    Abstract [en]

    The transistor laser is a relatively new device that is based on the homogeneous integration of a heterojunction bipolar transistor with a laser diode. As such it offers very unique functionality, and the different device dynamics (compared to conventional lasers) offer a number of benefits, included increased modulation bandwidth, reduced chirp, reduced relative intensity noise and the option to both reduce intermodulation distortion and to eliminate the need for monitor photodiodes thorough the use of collector current feedback. Here we review recent progress in both the fabrication and modelling of this device, and point to its potential applications in a number of areas of microwave photonics, including links and optoelectronic mixing.

  • 30. Jayasinghe, R. C.
    et al.
    Lao, Y. F.
    Perera, A. G. U.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Cao, C. F.
    Wu, H. Z.
    Plasma frequency and dielectric function dependence on doping and temperature for p-type indium phosphide epitaxial films2012In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 24, no 43, p. 435803-Article in journal (Refereed)
    Abstract [en]

    The optical properties of p-type InP epitaxial films with different doping concentrations are investigated by infrared absorption measurements accompanied by reflection and transmission spectra taken from 25 to 300 K. A complete dielectric function (DF) model, including intervalence band (IVB) transitions, free-carrier and lattice absorption, is used to determine the optical constants with improved accuracy in the spectral range from 2 to 35 mu m. The IVB transitions by free holes among the split-off, light-hole, and heavy-hole bands are studied using the DF model under the parabolic-band approximation. A good understanding of IVB transitions and the absorption coefficient is useful for designing high operating temperature and high detectivity infrared detectors and other optoelectronic devices. In addition, refractive index values reported here are useful for optoelectronic device designing, such as implementing p-InP waveguides in semiconductor quantum cascade lasers. The temperature dependence of hole effective mass and plasma frequency is also reported.

  • 31. Karim, A.
    et al.
    Gustafsson, Oscar
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Savage, S.
    Wang, Q.
    Almqvist, S.
    Asplund, C.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Jan, Y. A.
    In(Ga)Sb/InAs quantum dot based IR photodetectors with thermally activated photoresponse2013In: Proceedings of SPIE 8704, Infrared Technology and Applications XXXIX, SPIE - International Society for Optical Engineering, 2013, p. 870434-Conference paper (Refereed)
    Abstract [en]

    We report on the device characterization of In(Ga)Sb/InAs quantum dots (QDs) based photodetectors for long wave IR detectors. The detection principle of these quantum-dot infrared photodetectors (QDIPs) is based on the spatially indirect transition between the In(Ga)Sb QDs and the InAs matrix, as a result of the type-II band alignment. Such photodetectors are expected to have lower dark currents and higher operating temperatures compared to the current state of the art InSb and mercury cadmium telluride (MCT) technology. The In(Ga)Sb QD structures were grown using metal-organic vapour-phase epitaxy and explored using structural, electrical and optical characterization techniques. Material development resulted in obtaining photoluminescence up to 10 μm, which is the longest wavelength reported in this material system. We have fabricated different photovoltaic IR detectors from the developed material that show absorption up to 8 μm. Photoresponse spectra, showing In(Ga)Sb QD related absorption edge, were obtained up to 200 K. Detectors with different In(Ga)Sb QDs showing different cut-off wavelengths were investigated for photoresponse. Photoresponse in these detectors is thermally activated with different activation energies for devices with different cut-off wavelengths. Devices with longer cut-off wavelength exhibit higher activation energies. We can interpret this using the energy band diagram of the dots/matrix system for different QD sizes.

  • 32.
    Karim, Amir
    et al.
    Acreo.
    Gustafsson, Oscar
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hussain, Liaq
    Acrero.
    Wang, Q.
    Noharet, B.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Anderson, J.
    Song, J.
    Characterization of InSb QDs grown on InAs (100) substrate by MBE and MOVPE2012In: Proc SPIE Int Soc Opt Eng, 2012Conference paper (Refereed)
    Abstract [en]

    We report on the optical and structural characterization of InSb QDs in InAs matrix, grown on InAs (100) substrates, for infrared photodetection. InSb has 7% lattice mismatch with InAs forming strained QDs, which are promising for longwave IR applications, due to their type-II band alignment. This report contains material development results of InSb QDs for increasing their emission wavelength towards long-wave IR region. Samples were grown by two techniques of MBE and MOVPE, with different InSb coverage on InAs (100) substrates. Structures grown by MBE reveal QD related photoluminescence at 4 μm. AFM investigations of the MBE grown structures showed uncapped dots of ∼ 35 nm in size and ∼ 3 nm in height, with a density of about 2 × 1010 cm -2. Cross-section TEM investigations of buried InSb layers grown by MBE showed coherently strained QDs for nominal InSb coverage in the range of 1.6 - 2 monolayers (MLs). Layers with InSb coverage more than 2MLs contain relaxed QDs with structural defects due to large amount of strain between InSb and InAs. Samples with such large dots did not show any InSb related luminescence. The MOVPE grown InSb samples exhibit a strong QD related emission between 3.8 to 7.5 μm, depending on the amount of InSb coverage and other growth parameters. We report the longest wavelength observed so far in this material system.

  • 33. Kudrawiec, R.
    et al.
    Sek, G.
    Ryczko, K.
    Misiewicz, J.
    Sundgren, P.
    Asplund, C.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    The nature of optical transitions in Ga0.64In0.36As1-xNx/GaAs single quantum wells with low nitrogen content (x <= 0.008)2003In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 127, no 10-sep, p. 613-618Article in journal (Refereed)
    Abstract [en]

    Ga0.64In0.36As1-xNx/GaAs single quantum wells (SQWs) with low nitrogen content have been investigated by both photoluminescence (PL) and photoreflectance (PR) at low and room temperatures. A huge broadening of the PR features has been observed at low temperature and a decrease in this broadening with the temperature increase was detected. This effect and the nature of the optical transitions observed in absorption and emission can be explained using a model which assumes band gap variation due to different nitrogen nearest-neighbour environments (different configurations). In the framework of this model, the large Stokes shift observed for quantum wells (QWs) with smooth interfaces is explained as originating from the potential fluctuations of conduction band edge in the QW layer.

  • 34. Largeau, L.
    et al.
    Bondoux, C.
    Patriarche, G.
    Asplund, C.
    Fujioka, A.
    Salomonsson, F.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Structural effects of the thermal treatment on a GaInNAs/GaAs superlattice2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 79, no 12, p. 1795-1797Article in journal (Refereed)
    Abstract [en]

    We have studied structural changes that occur during annealing of GaInNAs/GaAs multiple quantum wells grown by metalorganic vapor-phase epitaxy (MOVPE). Different thermal treatments led to an improved room-temperature photoluminescence (PL) intensity, but also to room-temperature PL peak splitting. This splitting is related to the appearance of compositional clustering as displayed by transmission electron microscopy (TEM). In addition to this, interfacial layers on each side of the wells have also been observed by,TEM and their composition is discussed on the basis of high resolution x-ray diffraction studies. It is suggested that the interface layers are indium deficient, but enriched in nitrogen, degrading the optical quantum well performance and indicating a need for improved switching sequences in the MOVPE growth.

  • 35. Liu, S. -C
    et al.
    Zhao, D.
    Reuterskiold-Hedlund, Carl
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Liu, Z.
    Hammar, Mattias
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Zhou, W.
    Electrically pumped hybrid III-V/Si photonic crystal surface emitting lasers with buried tunnel-junction2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    We report here an electrically pumped hybrid photonic crystal surface emitting laser (PCSELs) on silicon. The laser cavity consists of a transferred InGaAsP multi-quantum well (MQW) heterostructure membrane, printed on a single layer silicon photonic crystal (Si-PC) cavity. A buried tunnel-junction (BTJ) has been employed in the MQW structure for efficiency charge injection. Single mode emitted spectrum was achieved at 1504 nm for a large area laser in the continuous-wave (c.w.) mode under room temperature operation.

  • 36. Liu, S.
    et al.
    Zhao, D.
    Yang, H.
    Ma, Z.
    Reuterskiöld-Hedlund, Carl
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zhou, W.
    Printed photonic crystal bandedge surface-emitting lasers on silicon2015In: CLEO: Science and Innovations, Optical Society of America, 2015Conference paper (Refereed)
    Abstract [en]

    We report experimental demonstration of a hybrid III-V/Si photonics crystal surface-emitting laser (PCSEL) based on membrane transfer printing technique. Single mode operation was observed with linewidth of 5 A and side-mode suppression ratio (SMSR) greater than 20 dB.

  • 37.
    Liu, Shih-Chia
    et al.
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Zhao, Deyin
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Ge, Xiaochen
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Reuterskiöld-Hedlund, Carl
    KTH, School of Information and Communication Technology (ICT).
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT).
    Fan, Shanhui
    Stanford Univ, Dept Elect Engn, Stanford, CA 94305 USA..
    Ma, Zhenqiang
    Univ Wisconsin, Dept Elect & Comp Engn, Madison, WI 53706 USA..
    Zhou, Weidong
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Size Scaling of Photonic Crystal Surface Emitting Lasers on Silicon Substrates2018In: IEEE Photonics Journal, ISSN 1097-5764, E-ISSN 1943-0655, Vol. 10, no 3, article id 4500506Article in journal (Refereed)
    Abstract [en]

    We report here the lateral cavity size scaling and confinement effects on the lasing performance in defect-free photonic crystal surface-emitting lasers (PCSEL) on silicon substrates Hybrid PCSELs with different lateral cavity sizes and different lateral confinement geometries have been fabricated using transfer printing technology and controlled selective etching The measured lasing properties show a strong dependence on the lateral cavity size below 100 mu m. In particular, the finite lateral dimension significantly affects the laser threshold and side mode suppression ratio (SMSR) of the PCSEL devices On the other hand, by controlling the lateral confinement using vertical etching, a reduction of the laser threshold is observed The experimental results agree well with theoretical predictions The work presented here can lead to ultra-compact PCSELs for on-chip integration with excellent energy efficiency.

  • 38.
    Liu, Shih-Chia
    et al.
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Zhao, Deyin
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Liu, Yonghao
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Yang, Hongjun
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Reuterskiöld-Hedlund, Carl
    KTH, School of Information and Communication Technology (ICT).
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT).
    Ma, Zhenqiang
    Univ Wisconsin, Dept Elect & Comp Engn, 1415 Johnson Dr, Madison, WI 53706 USA..
    Zhou, Weidong
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Photonic Crystal Surface-Emitting Lasers on Silicon Substrates2017In: 2017 IEEE PHOTONICS SOCIETY SUMMER TOPICAL MEETING SERIES (SUM), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 77-78Conference paper (Refereed)
    Abstract [en]

    We report here photonic crystal surface emitting lasers on bulk silicon substrates. Optically pumped lasers were demonstrated with single mode operation. Thermal resistance of such oxide-free cavity was investigated to evaluate the heat dissipation and lasing characteristics.

  • 39. Liu, Shih-Chia
    et al.
    Zhao, Deyin
    Yang, Hongjun
    Ma, Zhengiang
    Reuterskiold-Hedlund, Carl
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zhou, Weidong
    Room Temperature Photonic Crystal Bandedge Membrane Lasers on SOI Substrates2016In: 2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE conference proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    We report the experimental demonstration of room temperature photonics crystal (PC) bandedge membrane lasers on silicon based on the transfer printing technique. Single mode lasing was observed with linewidth of 4 angstrom and side-mode suppression ratio (SMSR) greater than 31.5 dB.

  • 40.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Dainese, Matteo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    High-power InGaAs/GaAs 1.3 mu m VCSELs based on novel electrical confinement scheme: Erratum2008In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 44, no 13Article in journal (Refereed)
  • 41.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Dainese, Matteo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    High-power InGaAs/GaAs 1.3 μm VCSELs based on novel electrical confinement scheme2008In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 44, no 6, p. 414-416Article in journal (Refereed)
    Abstract [en]

    Reported are 1.3 mu m InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a novel electrical confinement scheme based on lithographic definition and selective area epitaxial regrowth in the cavity region. More than 6 mW of output power with a record high differential efficiency of more than 70% is emitted from 10 mu m large devices.

  • 42.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ghisoni, Marco
    Zarlink Semiconductor AB.
    Oscarsson, Vilhelm
    Zarlink Semiconductor AB.
    Ödling, Elsy
    Zarlink Semiconductor AB.
    Malmquist, Jessica
    Zarlink Semiconductor AB.
    Fabrication and performance of 1.3-μm vertical cavity surface emitting lasers with InGaAs quantum well active regions grown on GaAs substrates2004In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5443, p. 229-239Article in journal (Refereed)
    Abstract [en]

    We describe the development of long-wavelength InGaAs/GaAs vertical-cavity surface emitting lasers (VCSELs). Using highly strained double-quantum wells (DQWs) in combination with negative gain-cavity detuning we have been able to realise such VCSELs with emission wavelength up to 1300 nm. High-performance device characteristics include mW-range output power, mA-range threshold currents, 10 Gbit/s data transmission and very good temperature stability with continuous-wave operation up to at least 140degreesC. Singlemode emission is realised using an integrated mode filter consisting of a patterned silicon layer on the out-coupling mirror surface, yielding output power and threshold currents for 1270-nm devices of 1.2 - 0.5 mW and 2.3 - 0.6 mA, respectively, over a temperature interval of 10 - 140degreesC. Multimode devices have been found to deliver more than 2 mW at 1290 nm. Preliminary lifetime measurements do not reveal any intrinsic reliability problems related to the highly strained quantum wells.

  • 43.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ghisoni, Marco
    Ödling, Elsy
    Oscarsson, Vilhelm
    Malmquist, Jessica
    1.3 μm InGaAs vertical-cavity surface-emitting lasers with mode filter for single mode operation2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 21, p. 4851-4853Article in journal (Refereed)
    Abstract [en]

    We report on the performance and analysis of 1.3 mum range InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with an integrated mode filter consisting of a patterned silicon layer on the top distributer Bragg reflector. In this way, 1 mW of single mode power is obtained from a device with a wavelength of 1265 nm and a threshold current of 2.6 mA at room temperature. An effective index model is used to extract the internal and external losses of the VCSEL structure and to predict the modal losses with and without mode filter, thereby providing a useful design tool for single mode VCSELs.

  • 44.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Yu, Xingang
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Performance optimisation of epitaxially regrown 1.3-μm vertical-cavity surface-emitting lasers2009In: IET Optoelectronics, ISSN 1751-8768, Vol. 3, no 2, p. 112-121Article in journal (Refereed)
    Abstract [en]

    A number of GaAs-based long-wavelength, vertical-cavity, surface-emitting laser structures with optical and electrical confinement based on selective area epitaxy have been fabricated and evaluated. The influence on output power, threshold current, thermal stability and modal properties from design parameters such as bottom-distributed Bragg reflector (DBR) doping, cavity doping, dielectric top DBR design and carrier confinement barriers is evaluated. More than 7 mW of output power is emitted from multimode devices with a square active region size of 10 mm. Single-mode power from smaller devices is restricted to 1.5 mW because of a non-optimal cavity shape.

  • 45.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Zhang, Zhenzhong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    A novel electrical and optical confinement scheme for surface emitting optoelectronic devices2006In: WORKSHOP ON OPTICAL COMPONENTS FOR BROADBAND COMMUNICATION / [ed] Fonjallaz, PY; Pearsall, TP, BELLINGHAM, WA: SPIE-INT SOC OPTICAL ENGINEERING , 2006, Vol. 6350, p. 63500J-1-63500J-10Conference paper (Refereed)
    Abstract [en]

    A novel electrical and optical confinement scheme for surface emitting optoelectronic devices is presented. The scheme is based on epitaxial regrowth of a pnp current blocking layer structure around a mesa etched in the vertical cavity region of the device. The lateral size and orientation of the mesa is defined lithographically and dry etching is used to create vertical mesa sidewalls. By orienting the mesa sidewalls in certain crystallographic directions, it is possible to selectively grow a current blocking pnp layer structure on the exposed n-type lower cladding layer of the cavity whithout obstructing the electrical injection into the active region. The concept is evaluated in 1.2-mu m GaAs-based light emitting diodes with InGaAs quantum wells. This type of structure can easily be used as the amplifying region of a vertical cavity laser, providing a good alternative to selective oxidation confinement.

  • 46. Martijn, H.
    et al.
    Asplund, C.
    Malm, H.
    Smuk, S.
    Höglund, L.
    Gustafsson, Oscar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hellström, Staffan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Development of IR imaging at IRnova2009In: Infrared Technology and Applications XXXV, 2009, Vol. 7298Conference paper (Refereed)
    Abstract [en]

    Historically IRnova has exclusively been a company, focused on manufacturing of QWIP detectors. Nowadays, besides continuous improvements of the performance of QWIP FPAs and development of new formats IRnova is involved in development of QWIP detectors for special applications and has started the development of the next generation infrared detectors, as well. In the light of the development of new formats we validate experimentally theoretical calculations of the response of QWIPs for smaller pixel size. These results allow for the development of high performance megapixel QWIP FPA that exhibit the high uniformity and operability QWIP detectors are known for. QWIP is also being considered for space applications. The requirements on dark current and operating temperature are however much more stringent as compared to the terrestrial applications. We show ways to improve the material quality with as a result a higher detector operating temperature. IRnova is also looking at antimony-based strained superlattice material for the LWIR region together with partners at theIMAGIC centre of excellence. One of the ways to overcome the problem with surface currents is passivating overgrowth. We will report the status and results of overgrowing the detector mesas with AlGa(As)Sb in a MOVPE system. At the same centre of excellence a novel material concept is being developed for LWIR detection. This new material contains a superlattice of vertically aligned and electronically coupled InAs and GaSb quantum dots. Simulations show that it should be possible to have LWIR detection in this material. We will present the current status and report results in this research.

  • 47. Menon, L.
    et al.
    Yang, H.
    Cho, S. J.
    Mikael, S.
    Ma, Z.
    Reuterskiöld-Hedlund, Carl
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zhou, W.
    Heterogeneously Integrated InGaAs and Si Membrane Four-Color Photodetector Arrays2016In: IEEE Photonics Journal, ISSN 1097-5764, E-ISSN 1943-0655, Vol. 8, no 2, article id 7445929Article in journal (Refereed)
    Abstract [en]

    We report the design and fabrication of heterogeneously integrated silicon and InGaAs membrane photodetector arrays. Visible and near-infrared (NIR) detection can be achieved by transfer printing a silicon membrane on InGaAs substrate. Based on the penetration-depth-dependent absorption of different wavelengths, filter-free visible color detection can be obtained via three-junction photocurrent measurement for silicon, and NIR can be detected by InGaAs. The measurements show good agreement with the optical behavior predicted by the design and simulation.

  • 48. Misiewicz, J.
    et al.
    Kudrawiec, R.
    Ryczko, K.
    Sek, G.
    Forchel, A.
    Harmand, J. C.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Photoreflectance investigations of the energy level structure in GaInNAs-based quantum wells2004In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 16, no 31, p. S3071-S3094Article in journal (Refereed)
    Abstract [en]

    In this paper, we present the application of photoreflectance (PR) spectroscopy to investigate the energy level structure of GaInNAs-based quantum wells (QWs). Series of single GaInNAs/GaAs QWs with different nitrogen and indium contents are analysed. The electron effective mass (m(e)(*)) and conduction e band offset (Q(C)) are determined and compared with the literature data. The Q(C) in GaInNAs/GaAs system in the range of investigated GaInNAs content (28-41% of In, 0.3-5.3% of N) has been found to be almost the same as for GaInAs/GaAs system, i.e. Q(C) approximate to 0.8. In addition, the energy level structure for the step-like GaInNAs/Ga(In)NAs/GaAs QWs tailored at 1.3 and 1.55 mum and the Sb-containing Ga(In)NAs/GaAs QWs is investigated. Also, the character of PR transitions, the influence of rapid thermal annealing (RTA) on the energy level structure, and the influence of the carrier localization effect on the efficiency of PR photomodulation are discussed.

  • 49. Mogg, S.
    et al.
    Chitica, N.
    Plaine, G.
    Hammar, Mattias
    Absolute reflectance measurements by a modified cavity phase-shift method2002In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 73, no 4, p. 1697-1701Article in journal (Refereed)
    Abstract [en]

    This article reports on a modified cavity phase-shift (CAPS) method for accurate and reliable characterization of high reflectance mirrors. Our approach relies on using a directly modulated Fabry-Perot laser to circumvent the difficulties encountered in previous attempts with the CAPS method. The Fabry-Perot laser diode ensures a constant coupling between the probe laser and test cavity modes. This results in a stable beam intensity transmitted through the test cavity allowing for accurate measurements of the phase shift from which the absolute reflectance can be determined. The experimental arrangement presented in this article is versatile and easy to use. The method is nondestructive and especially suited for the characterization of distributed Bragg reflectors (DBRs) employed in vertical-cavity optoelectronic devices. A premium feature of this method is its capability to probe a relatively small area of less than 1 mm which can be positioned anywhere across the surface of the wafer. We demonstrate the use of the method by measuring the absolute reflectance of metalorganic vapor-phase epitaxy grown AlAs/GaAs DBRs for 1.3 mum vertical-cavity lasers.

  • 50. Mogg, S.
    et al.
    Chitica, N.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Properties of highly strained InGaAs/GaAs quantum wells for 1.2-mu m laser diodes2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 13, p. 2334-2336Article in journal (Refereed)
    Abstract [en]

    The properties of 1.2-mum highly strained InGaAs quantum wells (QWs) grown on GaAs substrates have been analyzed. Optical gain spectra versus injection current and temperature, transparency current density, as well as other figures of merit were assessed from measurements on broad-area and ridge-waveguide lasers based on these QWs. Such active regions are of interest for a range of applications, including GaAs-based high-power lasers and vertical-cavity lasers for wavelengths beyond 1.2 mum.

123 1 - 50 of 107
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