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  • 1.
    Akram, Nadeem
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Silfvenius, Christofer
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Design optimization of InGaAsP-InGaAlAs 1.55 mu m strain-compensated MQW lasers for direct modulation applications2004In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 19, no 5, p. 615-625Article in journal (Refereed)
    Abstract [en]

    In this paper, a simulation study of InGaAsP(well)/InGaAlAs(barrier) 1.55 mum strain-compensated multi-quantum well (MQW) lasers is presented. Due to a large conduction band discontinuity in this material system, a higher material gain and differential gain can be obtained from such a quantum well (QW) as compared to a traditional InGaAsP/InGaAsP quantum well. The deeper electron well should also improve elevated temperature operating characteristics and reduce the electron spillover from QWs. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and the strain in the barriers. A large number of quantum wells can be uniformly pumped, reducing the carrier density in each individual well. A uniform and low carrier density in all the wells help reduce the total Auger recombination current. High p-doping in the active region is shown to enhance the carrier and gain non-uniformity in the MQWs. A simulated high modulation bandwidth has been demonstrated, promising directly modulated lasers as a low-cost source for short to medium distance (1-10 km) high speed optical links.

  • 2. Blank, T. V.
    et al.
    Goldberg, Y. A.
    Kalinina, E. V.
    Konstantinov, O. V.
    Konstantinov, A. O.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Temperature dependence of the photoelectric conversion quantum efficiency of 4H-SiC Schottky UV photodetectors2005In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 20, no 8, p. 710-715Article in journal (Refereed)
    Abstract [en]

    Ultraviolet Schottky photodetectors based on n-4H-SiC (N-d - N-a = 4 x 10(15) cm(-3)) epitaxial layers of high purity have been fabricated. Their spectral sensitivity range is 3.2-5.3 eV peaking at 4.9 eV (quantum efficiency is about similar to 0.3 electron/photon), which is close to the bactericidal ultraviolet radiation spectrum. The temperature dependence of the quantum efficiency of 4H-SiC Schottky structure has been investigated to determine the temperature stability and the mechanism of the photoelectric conversion process. At low temperatures (78-175 K) the quantum efficiency increases with increasing temperature for all photon energy values and then tends to saturate. We suppose that some imperfections in the space-charge region act as traps that capture both photoelectrons and photoholes. After some time the trapped electron-hole pairs recombine due to the tunnelling effect. At high temperatures (more than 300 K), the second enhancement region of the quantum efficiency is observed in the photon energy range of 3.2-4.5 eV. It is connected with a phonon contribution to indirect optical transitions between the valence band and the M-point of the conduction band. When the photon energy is close to a direct optical transition threshold this enhancement region disappears. This threshold is estimated to be 4.9 eV. At photon energies more than 5 eV a drastic fall of the quantum efficiency has been observed throughout the temperature interval. We propose that in this case the photoelectrons and photoholes are bound to form hot excitons in the space-charge region due to the Brillouin zone singularity, and do not contribute to the following photoelectroconversion process.

  • 3. Czernohorsky, M.
    et al.
    Tetzlaff, D.
    Bugiel, E.
    Dargis, R.
    Osten, H. J.
    Gottlob, H. D. B.
    Schmidt, M.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Kurz, H.
    Stability of crystalline Gd(2)O(3) thin films on silicon during rapid thermal annealing2008In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 23, no 3, p. 035010-Article in journal (Refereed)
    Abstract [en]

    We investigate the impact of rapid thermal anneals on structural and electrical properties of crystalline Gd(2)O(3) layers grown on Si with different orientations. Due to additional oxygen from the annealing ambient, a structureless two-layer stack ( silicon-oxide-like and silicate-like) between the silicon and the crystalline oxide will be formed. The degradation of layers can be significantly reduced by sealing the layer with a-Si prior to annealing. For the capped layers, the effective capacitance equivalent thickness increases only slightly even after a 1000 degrees C anneal.

  • 4.
    David, Denis
    et al.
    Univ Fed Bahia, Inst Fis, Campus Ondina, BR-40210340 Salvador, BA, Brazil. lnoor, Hatim; Nur, Omer; Willander, Magnus.
    Alnoor, Hatim
    Silva Santana, Victor Mancir
    Bargiela, Pascal
    Nur, Omer
    Willander, Magnus
    Baldissera, Gustavo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Univ Oslo, Dept Phys, POB 1048 Blindern, NO-0316 Oslo, Norway.
    Silva, Antonio Ferreira
    Optical properties from photoelectron energy-loss spectroscopy of low-temperature aqueous chemically synthesized ZnO nanorods grown on Si2019In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 34, no 4, article id 045019Article in journal (Refereed)
    Abstract [en]

    The optical properties of zinc oxide (ZnO) nanorods (NRs) synthesized by the low-temperature aqueous chemical method on top of silicon (Si) substrate have been investigated by means of photoelectron energy loss spectroscopy (PEELS). The ZnO NRs were obtained by the low temperature aqueous chemical synthesis on top of Si substrate. The measured valence band, the dynamical dielectric functions and optical absorption of the material show a reasonable agreement when the trending and shape of the theoretical calculations are considered. A first-principle calculation based on density functional theory (DFT) was performed using the partially self-consistent GW approximation (scGW(0)) and compared to the experimental results. The application of these two techniques brings a new analysis of the electronic properties of this material. The experimental results regarding the density of states (DOS) obtained for the valence band using x-ray photoelectron spectroscopy (XPS) was found to be consistent with the theoretical calculated value. Due to this consistency, the same wavefunctions was then employed to calculate the dielectric function of the ZnO NRs. The experimentally extracted dielectric function was also consistent with the calculated values.

  • 5.
    Davydova, Alexandra
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Tselikov, G.
    Dilone, D.
    Rao, K. Venkat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kabashin, A. V.
    Belova, Lyubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fabrication of thin ZnO films with wide-range tuned optical properties by reactive magnetron sputtering2018In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 33, no 2, article id 025004Article in journal (Refereed)
    Abstract [en]

    We report the manufacturing of thin zinc oxide films by reactive magnetron sputtering at room temperature, and examine their structural and optical properties. We show that the partial oxygen pressure in DC mode can have dramatic effect on absorption and refractive index (RI) of the films in a broad spectral range. In particular, the change of the oxygen pressure from 7% to 5% can lead to either conventional crystalline ZnO films having low absorption and characteristic descending dependence of RI from 2.4-2.7 RIU in the visible to 1.8-2 RIU in the near-infrared (1600 nm) range, or to untypical films, composed of ZnO nano-crystals embedded into amorphous matrix, exhibiting unexpectedly high absorption in the visible-infrared region and ascending dependence of RI with values varying from 1.5 RIU in the visible to 4 RIU in the IR (1600 nm), respectively. Untypical optical characteristics in the second case are explained by defects in ZnO structure arising due to under-oxidation of ZnO crystals. We also show that the observed defect-related film structure remains stable even after annealing of films under relatively high temperatures (30 min under 450 degrees C). We assume that both types of films can be of importance for photovoltaic (as contact or active layers, respectively), as well as for chemical or biological sensing, optoelectronics etc.

  • 6.
    Fang, Mei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Li, Hao
    Cent S Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Hunan, Peoples R China..
    Riazanova, Anastasiia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Rao, K Venkat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Belova, Lyubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Tuning room temperature ferromagnetism of 'in-situ' inkjet printed Fe-doped ZnO films2019In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 34, no 5, article id 055006Article in journal (Refereed)
    Abstract [en]

    ZnO is a wide-band gap semiconductor widely used in optical and electric devices, associating with ferromagnetism at low dimension endowing its possibility for functional applications with magneto-optical and magneto-electric properties. We prepared ZnO and Fe-doped ZnO thin films 'in-situ' on substrate by inkjet printing, and tuned the room temperature ferromagnetism (RTFM) of the film by Fe-doping concentration, film thickness and post annealing temperature. It was found that by Fe doping the saturation magnetization (M-s) of the film can be enhanced by more than 4 folds comparing with the un-doped film, i.e. from 0.9 emu g(-1) for the ZnO film to 3.8 emu g(-1) for the Fe-doped ZnO film with comparable thickness. The enhancement was attributed to the introduction of un-paired 3d electrons which formed long range ferromagnetic ordering, as well as the consequent structure changes with smaller grains which increased the interface induced magnetism. By changing the annealing temperature and the film thickness, the defect-induced ferromagnetism was investigated. The RTFM shows thickness dependence with peak saturation magnetization value of 4.44 emu g(-1) for the 45 nm thick film. The work provides an effective way of tuning magnetism in ZnO based films for functional device applications.

  • 7. Gaarder, A.
    et al.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Barrios, C. A.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Time-resolved micro-photoluminescence studies of deep level distribution in selectively regrown GaInP: Fe and GaAs : Fe2002In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 17, no 2, p. 129-134Article in journal (Refereed)
    Abstract [en]

    We apply time-resolved photoluminescence with 1-2 mum spatial resolution for the characterization of deep centre distributions in semi-insulating GaInP:Fe and GaAs:Fe epitaxial layers regrown by hydride vapour phase epitaxy around etched GaAs mesas and GaAs/AlGaAs quantum well laser structures. In InGaP, Fe ions act as the main carrier recombination centres, while in Fe-doped GaAs both the Fe ions and As antisite defects have to be considered. The distribution of Fe ions in InGaP was found to be rather uniform and close to the target value. For GaAs:Fe, the number of ionized Fe and EL2 centres showed a certain increase at the mesa interfaces. In both cases, the high trap concentration was maintained throughout the regrown layers indicating good semi-insulating material properties.

  • 8. Healy, Noel
    et al.
    Gibson, Ursula
    Norwegian Univ of Science and Technol..
    Peacock, Anna
    A review of materials engineering in silicon-based optical fibresIn: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641Article in journal (Refereed)
    Abstract [en]

    Semiconductor optical fibre technologies have grown rapidly in the last decade and there are now a range of production and post-processing techniques that allow for a vast degree of control over the core material's optoelectronic properties. These methodologies and the unique optical fibre geometry provide an exciting platform for materials engineering and fibres can now be produced with single crystal cores, low optical losses, tunable strain, and inscribable phase composition. This review discusses the state-of-the-art regarding the production of silicon optical fibres in amorphous and crystalline form and then looks at the post-processing techniques
 and the improved material quality and new functionality that they afford.

  • 9. Huang, Dan
    et al.
    Jiang, Jing-Wen
    Guo, Jin
    Zhao, Yu-Jun
    Chen, Rongzhen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Group-IV (Si, Ge, and Sn)-doped AgAlTe2 for intermediate band solar cell from first-principles study2017In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 32, no 6, p. 065007-065014, article id 065007Article in journal (Refereed)
    Abstract [en]

    Earlier studies of chalcopyrites as the absorber for intermediate band solar cells (IBSCs) mainly focused on Cu-based compounds, whose intermediate band is usually empty due to its intrinsic p-type conductivity. This is not beneficial to the two sub-bandgap absorptions. In this paper, we demonstrate that the intermediate bands in group IV (Si, Ge, and Sn) doped AgAlTe2 are delocalized and mainly contributed by the anti-bonding state of group-IV elements s state and Te-p state. Overall, we suggest that Sn-doped AgAlTe2 should be a promising absorber candidate for IBSCs based on the theoretical efficiency and defect stability.

  • 10. Johansson, M
    et al.
    Yousif, MYA
    Lundgren, P
    Bengtsson, S
    Sundqvist, J
    Harsta, A
    Radamson, Henry H.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    HfO2 gate dielectrics on strained-Si and strained-SiGe layers2003In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 18, no 9, p. 820-826Article in journal (Refereed)
    Abstract [en]

    We report on materials and device characterization of polycrystalline HfO2 gate dielectrics grown by atomic layer deposition (ALD) at 600 degreesC on strained-Si and strained-SiGe layers. No change in the diffusion profile of Hf into the Si substrate was observed for temperatures in the range 900-1100 degreesC for 20 min. The strain status in the Si layer remained unaltered after HfO2 deposition and an interface state density of similar to1 x 10(11) cm(-2) eV(-1) was obtained for the thicker HfO2 films. The breakdown fields were in the range 2-5 MV cm(-1), which is high compared to HfO2 films grown at higher temperatures. The leakage current was reduced by more than five orders of magnitude for the thin HFO2 with an EOT of 1.25 nm and ultra-thin cap (2.5-3 nm) layers on Si0.77Ge0.23/Si, though high interface state densities (similar to1 x 10(12) cm(-2) eV(-1)) were observed. The carrier transport through these HfO2 films was found to follow Frenkel-Poole emission over a wide range of applied gate voltages.

  • 11.
    Kataria, Himanshu
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Junesand, Carl
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Wang, Zhechao
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Metaferia, Wondwosen
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Sun, Yan-Ting
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Bazin, Alexandre
    CNRS.
    Raineri, Fabrice
    CNRS.
    Mages, Phil
    UCSB.
    Julian, Nick
    UCSB.
    Bowers, John
    UCSB.
    Towards a monolithically integrated III-V laser on silicon: Optimization of multi-quantum well growth of InP on Si2013In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 28, no 9, p. 094008-Article in journal (Refereed)
    Abstract [en]

    High-quality InGaAsP/InP multi-quantum wells (MQWs) on the isolated areas of indium phosphide on silicon necessary for realizing a monolithically integrated silicon laser is achieved. Indium phosphide layer on silicon, the pre-requisite for the growth of quantum wells is achieved via nano-epitaxial lateral overgrowth (NELOG) technique from a defective seed indium phosphide layer on silicon. This technique makes use of epitaxial lateral overgrowth (ELOG) from closely spaced (1 m) e-beam lithography-patterned nano-sized openings (∼300 nm) by low-pressure hydride vapor phase epitaxy. A silicon dioxide mask with carefully designed opening patterns and thickness with respect to the opening width is used to block the defects propagating from the indium phosphide seed layer by the so-called necking effect. Growth conditions are optimized to obtain smooth surface morphology even after coalescence of laterally grown indium phosphide from adjacent openings. Surface morphology and optical properties of the NELOG indium phosphide layer are studied using atomic force microscopy, cathodoluminescence and room temperature -photoluminescence (-PL) measurements. Metal organic vapor phase epitaxial growth of InGaAsP/InP MQWs on the NELOG indium phosphide is conducted. The mask patterns to avoid loading effect that can cause excessive well/barrier thickness and composition change with respect to the targeted values is optimized. Cross-sectional transmission electron microscope studies show that the coalesced NELOG InP on Si is defect-free. PL measurement results indicate the good material quality of the grown MQWs. Microdisk (MD) cavities are fabricated from the MQWs on ELOG layer. PL spectra reveal the existence of resonant modes arising out of these MD cavities. A mode solver using finite difference method indicates the pertinent steps that should be adopted to realize lasing.

  • 12. Krotkus, A.
    et al.
    Marcinkevicius, S.
    Pasiskevicius, Valdas
    Olin, U.
    Ultrafast luminescence decay in low-temperature MOCVD-grown InGaAs1994In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 9, no 7, p. 1382-1386Article in journal (Refereed)
  • 13.
    Krotkus, Arunas
    et al.
    Semiconductor Physics Institute, Vilnius, Lithuania.
    Marcinkevicius, Saulius
    Semiconductor Physics Institute, Vilnius, Lithuania.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI).
    Olin, Ulf
    Institute för Optis Forskning.
    Ultrafast luminescence decay in low-temperature MOCVD-grown InGaAs1994In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 9, p. 1382-1386Article in journal (Refereed)
  • 14.
    Kumar, Mukesh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Zhao, Hanyue
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Study of band-structure, optical properties and native defects in A IBIIIO2 (AI = Cu or Ag, B III = Al, Ga or In) delafossites2013In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 28, no 6, p. 065003-Article in journal (Refereed)
    Abstract [en]

    In this work, employing a first-principles approach, the structural, electronic, optical, as well as the defect physics of AIB IIIO2 (AI = Cu or Ag, BIII = Al, Ga or In) compounds are discussed. We show that all these delafossite compounds have indirect band gaps with gap energy in the range = 1.6-3.6 eV. We also estimate the lowest direct band gap energies to be in the range = 2.6-4.0 eV. Optical characteristics reveal that AIBIIIO2 compounds exhibit a significant anisotropy for both the real and imaginary parts of the dielectric function. Furthermore, we find that absorption onset for these compounds is energetically well above (>1.5 eV) the fundamental band gaps. Moreover, we demonstrate that the copper delafossites have larger absorption coefficients compared to the corresponding BIII cation silver delafossites in the visible range. Defect calculations reveal that Cu or Ag vacancy has the lowest formation energy followed by the O vacancy while the BIII cation vacancy has the highest formation energy.

  • 15. Liberis, J.
    et al.
    Matulioniene, I.
    Matulionis, A.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Kurz, H.
    Foerst, M.
    Hot-phonon temperature and lifetime in biased boron-implanted SiO2/Si/SiO2 channels2006In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 21, no 6, p. 803-807Article in journal (Refereed)
    Abstract [en]

    Microwave noise temperature is measured as a function of supplied electric power in 100 nm thick silicon on insulator layers. At 293 K, the estimated hot-hole energy-relaxation time decreases from similar to 9 ps at power below 0.05 nW/hole down to similar to 1.55 ps in the power range (2-10) nW/hole. The results are interpreted in terms of hot-hole interaction with longitudinal optical (LO) phonons. A comparison of the experimental data with those calculated in the hot-hole-temperature approximation indicates accumulation of non-equilibrium optical phonons (termed hot phonons). In the power range of the dominant hole-LO phonon interaction, the increase in equivalent hot-phonon temperature is proportional to the increase in hot-hole temperature. The estimated value for the hot-phonon lifetime, (1.75 +/- 0.4) ps, is comparable with the hot-hole energy-relaxation time at the high bias, similar to 1.55 ps.

  • 16.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Sztein, Alexander
    Nakamura, Shuji
    Speck, James S.
    Properties of sub-band edge states in AlInN studied by time-resolved photoluminescence of a AlInN/GaN heterostructure2015In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 30, no 11, article id 115017Article in journal (Refereed)
    Abstract [en]

    Time-resolved photoluminescence (PL) measurements of Al0.82In0.18N/GaN heterostructures revealed a large enhancement of low temperature PL from the GaN layer and a strong temperature dependence of this effect. Analysis of different phenomena that might affect the photoexcited carrier dynamics suggests that the enhanced GaN PL should be attributed to photoexcited hole transfer from the AlInN layer. The hole transport most probably takes place via dense sub-band edge valence band states related to nanoscale In-rich clusters. Scanning near-field optical microscopy data support this assignment.

  • 17. Punkkinen, M. P. J.
    et al.
    Laukkanen, P.
    Kuzmin, M.
    Levamaki, H.
    Lang, J.
    Tuominen, M.
    Yasir, M.
    Dahl, J.
    Lu, Song
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Delczeg-Czirjak, E. K.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden; Institute for Solid State Physics and Optics, Hungary .
    Kokko, K.
    Does Bi form clusters in GaAs1-xBix alloys?2014In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 29, no 11, p. 115007-Article in journal (Refereed)
    Abstract [en]

    GaAs1 - xBix alloys attract significant interest due to their potentiality for several applications, including solar cells. Recent experiments link the crucial optical properties of these alloys to Bi clustering at certain Bi compositions. Using ab initio calculations, we show that there is no thermodynamical driving force for the formation of small GaBi clusters incorporating As substitutional sites. However, the Ga vacancies should gather Bi atoms leading to small Bi clusters, and the Ga vacancies can act as nucleation centers for phase separation. The formation energy of the GaAs1 - xBix with respect to GaAs and GaBi shows a maximum at intermediate Bi concentrations. Thermodynamics and kinetics of the GaAs1 - xBix film growth is discussed. High Bi solubility is obtained, if the Bi atoms on the energetically favorable atom positions in the subsurface layer are relatively frozen. The Ga vacancy concentration may be increased by the incorporation of Bi. The Bi atoms can also prevent the out diffusion of Ga vacancies.

  • 18.
    Radamson, Henry H.
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hållstedt, Julius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Integration of selective SiGe epitaxy for source/drain application in MOSFETs2006In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 22, no 1, p. 123-126Article in journal (Refereed)
    Abstract [en]

    The integration of HCl chemical vapour etching and selective epitaxy by chemical vapour deposition of B-doped SiGe layers for recessed source/drain junction application has been studied. A temperature range of 850-900 degrees C is proposed to be suitable for the etch process in order to obtain a smooth Si surface. This point is crucial for the epitaxial quality of grown SiGe: B layers. The selectivity of the epitaxy was not as good for high B partial pressure. However, Si0.76Ge0.24 layers with a B concentration of 6 x 10(20) cm(-3) were selectively grown. The pattern dependence of the etch and epitaxy process was studied and a calibration of this versus Si coverage of the chip was performed.

  • 19. Wang, Lijuan
    et al.
    He, Jifang
    Shang, Xiangjun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Mifeng
    Yu, Ying
    Zha, Guowei
    Ni, Haiqiao
    Niu, Zhichuan
    Enhanced tunneling in the GaAs p(+)-n(+) junction by embedding InAs quantum dots2012In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 27, no 11, p. 115010-Article in journal (Refereed)
    Abstract [en]

    GaAs p(+)-n(+) junctions with and without a layer of InAs quantum dots (QDs) embedded at the interface are discussed in this article. The current density versus voltage (I-V) characteristics show that the junctions without QDs are weak degenerate due to the Beryllium(Be) atoms diffusion of nominal p(++)-GaAs; the junctions with QDs generate enhanced tunneling current at forward bias, because the QDs layer reduces the Be diffusion and enables a two-step tunneling process. At room temperature, the current density of the sample with QDs is enhanced to 122 A cm(-2) at a forward bias of +0.32 V, which is about 2 orders of magnitude higher than the reference sample without QDs.

  • 20.
    Zetterling, Carl-Mikael
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Hedayati, Raheleh
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Kargarrazi, Saleh
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Lanni, Luigia
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Malm, B. Gunnar
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Mardani, S.
    Norström, H.
    Rusu, Ana
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Suvanam, Sethu Saveda
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Tian, Ye
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Bipolar integrated circuits in SiC for extreme environment operation2017In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 32, no 3, article id 034002Article in journal (Refereed)
    Abstract [en]

    Silicon carbide (SiC) integrated circuits have been suggested for extreme environment operation. The challenge of a new technology is to develop process flow, circuit models and circuit designs for a wide temperature range. A bipolar technology was chosen to avoid the gate dielectric weakness and low mobility drawback of SiC MOSFETs. Higher operation temperatures and better radiation hardness have been demonstrated for bipolar integrated circuits. Both digital and analog circuits have been demonstrated in the range from room temperature to 500 °C. Future steps are to demonstrate some mixed signal circuits of greater complexity. There are remaining challenges in contacting, metallization, packaging and reliability.

  • 21.
    Zhang, Andy Zhenzhong
    et al.
    Acreo, Sweden .
    Wang, Qin
    Karlsson, Stefan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101). Kista Photonics Resarch Center, Sweden.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101). Kista Photonics Resarch Center, Sweden.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101). Kista Photonics Resarch Center, Sweden.
    Fonjallaz, Pierre-Yves
    Almqvist, Susanne
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101).
    Thylen, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101). Kista Photonics Resarch Center, Sweden.
    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.
    Honecker, Joerg
    Steffan, Andreas
    Fabrication of an electro-absorption transceiver with a monolithically integrated optical amplifier for fiber transmission of 40-60 GHz radio signals2011In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 26, no 1, p. 014042-Article in journal (Refereed)
    Abstract [en]

    We report on the fabrication of a monolithically integrated semiconductor optical amplifier (SOA) and a reflective electro-absorption transceiver (EAT) for 40-60 GHz radio-over-fiber applications. The EAT can either function as a transmitter (reflective modulator) or as a receiver (photodetector) depending on operation mode. The SOA and the EAT sections are based on different InGaAsP multiple quantum-well active layers connected by a butt joint. Benzocyclobutene is used to reduce the capacitance beside the ridge mesa. Devices are designed to have a peaked response at the operating frequency through the design of microwave waveguides on top of the devices. The packaged device exhibits at 0.1 mW optical input power an amplified DC responsivity of 18.5 mA mW(-1) and a modulation efficiency of 0.67 mW V-1. The estimated radio frequency loss at 40 GHz of an optical link consisting of two SOA-EAT devices was 23 dB using an unmodulated optical input carrier to the transmitter of 0.94 mW.

  • 22.
    Östling, Mikael
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Gutierrez, Edmundo
    Alquier, Daniel
    Simoen, Eddy
    An editorial on the recent advances in high and low temperature electronics2017In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 32, no 8, article id 080201Article in journal (Refereed)
1 - 22 of 22
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