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  • 1. Aberg, D
    et al.
    Hallberg, T
    Svensson, B G
    Lindstrom, J L
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Ultra-shallow thermal donor formation in oxygen-containing ambient1998In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 210, p. 527-532Article in journal (Refereed)
    Abstract [en]

    Czochralski-grown phosphorus-doped (approximate to 2 x 10(14) cm(-3)) silicon wafers have been annealed in nitrogen, wet nitrogen, argon, oxygen, and vacuum ambients at 470 degrees C for times up to 500 h. Sample characterization was made with capacitance-voltage, four-point probe, DLTS, thermally stimulated capacitance, admittance spectroscopy, secondary ion-mass spectrometry, and Fourier transform infrared spectroscopy. This study finds a strong relation between the previously reported ultra-shallow thermal donors (USTDs) and shallow thermal donors (STDs), and it is shown that the net concentration of thermally formed donors is independent on annealing ambient within the experimental accuracy. It was found that the majority of formed donors for long anneals consisted of either STDs or USTDs, however, it was found that oxygen-containing ambient is indispensable for forming USTDs.

  • 2. Aberg, D
    et al.
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Svensson, B G
    Hallberg, T
    Lindstrom, J L
    Ultrashallow thermal donor formation in silicon by annealing in ambient oxygen1999In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 85, p. 8054-8059Article in journal (Refereed)
    Abstract [en]

    Czochralski-grown silicon wafers doped with phosphorus (similar to 10(14) cm(-3)) have been annealed in nitrogen, wet nitrogen, oxygen, argon, and vacuum ambients at 470 degrees C for times up to 500 h. Sample characterization was made using predominantly electrical techniques such as admittance spectroscopy and thermally stimulated capacitance measurements but also secondary ion mass spectrometry (SIMS) and Fourier transform infrared spectroscopy were employed. In all samples, an increasing concentration of free carrier electrons is observed with increasing annealing time, reaching a maximum of similar to 10(16) cm(-3) at 100 h. For durations in excess of 100 h gradual decrease of the free electron concentration takes place except for the samples treated in wet nitrogen and oxygen atmospheres, which display donors stable even after 200 h. These stable centers are found to have shallower donor level positions in the energy band gap (similar to 25 meV below the conduction band edge E-c) than those of the centers formed in vacuum, argon, and nitrogen atmospheres (similar to 35 meV below E-c). The latter centers are associated with the well-established shallow thermal donors (STDs) while the origin of the former ones, which are labeled ultrashallow thermal donors (USTDs) is less known. However, on the basis of a wealth of experimental results we show that the USTDs are most likely perturbated STDs modified through interaction with fast-in diffusing oxygen species, possibly oxygen dimers. Further, comparison between the electrical data and the SIMS measurements reveals unambiguously that neither the STD nor the USTD centers involve nitrogen, in contrast to recent suggestions in the literature. (C) 1999 American Institute of Physics. [S0021-8979(99)06512-3].

  • 3. Achtziger, N
    et al.
    Grillenberger, J
    Witthuhn, W
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Janson, M S
    Svensson, B G
    Hydrogen passivation of silicon carbide by low-energy ion implantation1998In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 73, p. 945-947Article in journal (Refereed)
    Abstract [en]

    implantation of deuterium is performed to investigate the mobility and passivating effect of hydrogen in epitaxial alpha-SiC (polytypes 4H and 6H). To avoid excessive damage and the resulting trapping of hydrogen, the implantation is performed with low energy (600 eV H-2(2)+). The H-2 depth profile is analyzed by secondary ion mass spectrometry. Electrical properties are measured by capacitance-voltage profiling and admittance spectroscopy. In p-type SIG, hydrogen diffuses on a mu m scale even at room temperature and effectively passivates accepters. In n-type SiC, the incorporation of H is suppressed and no passivation is detected. (C) 1998 American Institute of Physics.

  • 4. Achtziger, N
    et al.
    Hulsen, C
    Janson, M
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Svensson, B G
    Witthuhn, W
    Formation of passivated layers in p-type SiC by low energy ion implantation of hydrogen2000In: SILICON CARBIDE AND RELATED MATERIALS - 1999 PTS, 1 & 2, 2000, Vol. 338-3, p. 933-936Conference paper (Refereed)
    Abstract [en]

    The mobility of hydrogen and its passivating effect on accepters in p-type SiC is investigated. Hydrogen (isotope H-1 or H-2 alternatively) is implanted at temperatures between 300 K and 680 K with low energy (300 eV per atom) in order to minimize implantation damage. The depth profiles of 2H and of passivated accepters correspond closely. Up to 500 K, a fully passivated layer with a well defined thickness is formed. Its depth ton the order of 1 micrometer) is investigated as a function of doping level and hydrogen fluence. At higher temperatures, the incorporation drastically increases, but the electrical passivation is partial only. Qualitative explanations are given.

  • 5. Achtziger, N
    et al.
    Hulsen, C
    Witthuhn, W
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Janson, M
    Svensson, B G
    Mobility passivating effect and thermal stability of hydrogen in silicon carbide1998In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 210, p. 395-399Article in journal (Refereed)
    Abstract [en]

    The diffusion and passivating effect of hydrogen (isotope H-2) in epitaxial p-type SiC is studied by secondary ion mass spectrometry and capacitance-voltage profiling on Schottky diodes. The incorporation of hydrogen is achieved by low-energy ion implantation. The influence of implantation energy, temperature and subsequent annealing is presented. Annealing experiments with an electric field applied reveal a reactivation of passivated accepters and a H+ ion drift at a surprisingly low temperature of 530 K.

  • 6.
    Aggerstam, Thomas
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Electron and hole capture cross-sections of Fe acceptors in GaN:Fe epitaxially grown on sapphire2007In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 36, no 12, p. 1621-1624Article in journal (Refereed)
    Abstract [en]

    Carrier trapping of Fe (3+)/Fe2+ deep acceptors in epitaxially grown GaN:Fe on sapphire was studied by time-resolved photoluminescence. For the investigated Fe doping levels on the order of 10(18) cm(-3), the luminescence decay times are strongly dependent on the Fe concentration, indicating that Fe centers act as predominant nonradiative recombination channels. Linear dependence of the decay time on the iron concentration allows estimation of the electron capture cross-section for the Fe3+ ions, which is equal to 1.9 x 10(-15) cm(2). The upper bound for the cross-section of the hole capture of Fe2+ was evaluated as 10 x 10(-15) cm

  • 7. AHLSTROM, M
    et al.
    JONSSON, B
    KARLSTROM, G
    ABINITIO MOLECULAR-ORBITAL CALCULATIONS ON HYDROGEN-BONDED AND NON-HYDROGEN-BONDED COMPLEXES - H2CO.H2O AND H2CO.H2S1979In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 38, p. 1051-1059Article in journal (Refereed)
  • 8. Alfieri, G.
    et al.
    Monakhov, E. V.
    Svensson, B. G.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Annealing behavior between room temperature and 2000 degrees C of deep level defects in electron-irradiated n-type 4H silicon carbide2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 98, no 4Article in journal (Refereed)
    Abstract [en]

    The annealing behavior of irradiation-induced defects in 4H-SiC epitaxial layers grown by chemical-vapor deposition has been systematically studied by means of deep level transient spectroscopy (DLTS). The nitrogen-doped epitaxial layers have been irradiated with 15-MeV electrons at room temperature and an isochronal annealing series from 100 to 2000 degrees C has been performed. The DLTS measurements, which have been carried out in the temperature range from 120 to 630 K after each annealing step, revealed the presence of six electron traps located in the energy range of 0.45-1.6 eV below the conduction-band edge (E-c). The most prominent and stable ones occur at E-c-0.70 eV (labeled Z(1/2)) and E-c-1.60 eV(EH6/7). After exhibiting a multistage annealing process over a wide temperature range, presumably caused by reactions with migrating defects, a significant fraction of both Z(1/2) and EH6/7 (25%) still persists at 2000 degrees C and activation energies for dissociation in excess of 8 and similar to 7.5 eV are estimated for Z(1/2) and EH6/7, respectively. On the basis of these results, the identity of Z(1/2) and EH6/7 is discussed and related to previous assignments in the literature.

  • 9. Alfieri, G
    et al.
    Monakhov, EV
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Svensson, BG
    Capacitance spectroscopy study of high energy electron irradiated and annealed 4H-SIC2005In: SILICON CARBIDE AND RELATED MATERIALS 2004 / [ed] Nipoti, R; Poggi, A; Scorzoni, A, ZURICH-UETIKON: TRANS TECH PUBLICATIONS LTD , 2005, Vol. 483, p. 365-368Conference paper (Refereed)
    Abstract [en]

    Deep level transient spectroscopy (DLTS) was employed to investigate the annealing behaviour and thermal stability of radiation induced defects in nitrogen doped 4H-SiC epitaxial layers, grown by chemical vapor deposition (CVD). The epilayers have been irradiated with 15 MeV electrons and an isochronal annealing series has been carried out. The measurements have been performed after each annealing step and six electron traps located in the energy band gap range of 0.42-1.6 eV below the conduction band edge (E-c) have been detected.

  • 10. Audren, A.
    et al.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Possnert, G.
    Damage recovery in ZnO by post-implantation annealing2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 11-12, p. 1842-1846Article in journal (Other academic)
    Abstract [en]

    ZnO bulk samples were implanted with 200 key-Co ions at room temperature with two fluences, 1 x 10(16) and 8 x 10(16) cm(-2), and then annealed in air for 30 min at different temperatures up to 900 degrees C. After the implantation and each annealing step, the samples were analyzed by Rutherford backscattering spectrometry (RBS) in random and channeling directions to follow the evolution of the disorder profile. The RBS spectra reveal that disorder is created during implantation in proportion to the Co fluence. The thermal treatments induce a disorder recovery, which is however, not complete after annealing at 900 degrees C, where about 15% of the damage remains. To study the Co profile evolution during annealing, the samples were, in addition to RBS, characterized by secondary ion mass spectrometry (SIMS). The results show that Co diffusion starts at 800 degrees C, but also that a very different behavior is seen for Co concentrations below and above the solubility limit. (C) 2010 Elsevier B.V. All rights reserved.

  • 11. Doyle, J. P.
    et al.
    Abolfotoh, M. O.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Electronics.
    Svensson, B. G.
    Schoener, A.
    Nordell, Nils
    KTH, Superseded Departments, Electronics.
    Harris, C.
    Lindström, J. L.
    Janzen, E.
    Hemmingsson, C.
    Characterization of deep level defects in 4H and 6H SiC via DLTS, SIMS and MeV e-beam irradiation1996In: III-nitride, SiC and diamond materials for electronic devices: Proceedings of the Symposium, San Francisco, CA; UNITED STATES; 8-12 Apr. 1996., 1996, p. 519-524Conference paper (Refereed)
    Abstract [en]
    Electrically active defects in both 4H and 6H polytypes of SiC have been observed through the use of deep level transient spectroscopy (DLTS). Schottky contacts were grown by VPE with doping concentrations, the epitaxial layer having a doping concentration in the range of 10 exp 14/cu cm to 10 exp 17/cu cm. Numerous levels have been found in the as-grown n-type 6H-SiC samples, and SIMS and MeV electron irradiation have been employed to correlate the defect levels to impurities or structural defects. In contrast, only a single level is observed in the as-grown 4H-SiC samples.
  • 12.
    Doyle, J. P.
    et al.
    KTH, Superseded Departments, Electronics.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Electronics.
    Pellegrino, Paolo
    KTH, Superseded Departments, Electronics.
    Keskitalo, N.
    KTH, Superseded Departments, Electronics.
    Svensson, B. G.
    KTH, Superseded Departments, Electronics.
    Schöner, A.
    Nordell, N.
    Lindström, J. L.
    Electrically active point defects in n-type 4H–SiC1998In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 84, no 3, p. 61-68Article in journal (Refereed)
    Abstract [en]

    An electrically active defect has been observed at a level position of ∼ 0.70 eV below the conduction band edge (Ec) with an extrapolated capture cross section of ∼ 5×10−14 cm2 in epitaxial layers of 4H–SiC grown by vapor phase epitaxy with a concentration of approximately 1×1013 cm−3. Secondary ion mass spectrometry revealed no evidence of the transition metals Ti, V, and Cr. Furthermore, after electron irradiation with 2 MeV electrons, the 0.70 eV level is not observed to increase in concentration although three new levels are observed at approximately 0.32, 0.62, and 0.68 eV below Ec with extrapolated capture cross sections of 4×10−14, 4×10−14, and 5×10−15 cm2, respectively. However, the defects causing these levels are unstable and decay after a period of time at room temperature, resulting in the formation of the 0.70 eV level. Our results suggest strongly that the 0.70 eV level originates from a defect of intrinsic nature. The unstable behavior of the electron irradiation-induced defects at room temperature has not been observed in the 6H–SiC polytype.

  • 13. Doyle, J P
    et al.
    Schoner, A
    Nordell, N
    Galeckas, A
    Bleichner, H
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Linnros, J
    Svensson, B G
    Observation of near-surface electrically active defects in n-type 6H-SiC1998In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 83, p. 3649-3651Article in journal (Refereed)
    Abstract [en]

    In n-type 6H-SiC epitaxial layers grown by vapor phase epitaxy, we find that in contrast to the majority of the epitaxial layer, where electrically active defects are observed with a concentration less than 1 X 10(-13) cm(-3), a region near the front surface contains defects with concentrations approaching 10(14) cm(-3). A relationship between the near-surface defects and metallic impurities is suggested by a Ti concentration of 1 X 10(16) cm(-3) in this region. The high concentration of near surface defects is found to significantly reduce the carrier lifetime. (C) 1998 American Institute of Physics. [S0021-8979(98)03007-2].

  • 14. Fage-Pedersen, J.
    et al.
    Larsen, A. N.
    Gaiduk, P.
    Hansen, J. L.
    Linnarsson, M.
    KTH, School of Information and Communication Technology (ICT).
    Sn-background-induced diffusion enhancement of Sb in Si1998In: Physical Review Letters, ISSN 00319007 (ISSN), Vol. 81, no 26, p. 5856-5859Article in journal (Refereed)
    Abstract [en]

    The diffusion of Sb in Si has been studied as a function of Sn-background concentration, and enhanced Sb diffusion is observed for backgrounds higher than CSn1 = 5 × 1019 cm-3. This concentration for the onset of enhanced diffusion is significantly lower than in other reports of high-concentration vacancy-mediated diffusion in Si. These reports, however, have up to now been concerned with donor impurities, whereas Sn is an electrically neutral impurity. Some Sn precipitation occurred, and the influence upon the diffusion is estimated from experiment to be small. A number of proposed models of high-concentration diffusion are discussed on the basis of the data.

  • 15. Forsberg, U
    et al.
    Danielsson, O
    Henry, A
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Janzen, E
    Aluminum doping of epitaxial silicon carbide grown by hot-wall CVD; Effect of process parameters2002In: SILICON CARBIDE AND RELATED MATERIALS 2001, PTS 1 AND 2, PROCEEDINGS, 2002, Vol. 389-3, p. 203-206Conference paper (Refereed)
    Abstract [en]

    Intentional p-type doping of SiC has been performed by using trimethylaluminum as dopant source. A comprehensive investigation of the aluminum incorporation dependency on temperature, pressure, C/Si ratio and growth rate in a horizontal hot-wall CVD reactor has been made. The incorporation mechanism for 4H and 6H-SiC both for Si- and C-face material is presented.

  • 16. Forsberg, U.
    et al.
    Danielsson, O.
    Henry, A.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Janzen, E.
    Aluminum doping of epitaxial silicon carbide2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 253, no 04-jan, p. 340-350Article in journal (Refereed)
    Abstract [en]

    Intentional doping of aluminum in 4H and 6H SiC has been performed using a hot-wall CVD reactor. The dependence of aluminum incorporation on temperature, pressure, C/Si ratio, growth rate, and TMA flow has been investigated. The aluminum incorporation showed to be polarity dependent. The high aluminum incorporation on the Si-face is closely related to the carbon coverage on the SiC surface. Changes in process parameters changes the effective C/Si ratio close to the SiC surface. Increased growth rate and C/Si ratio increases the aluminum incorporation on the Si-face. Diffusion limited incorporation occurs at high growth rate. Reduced pressure increases the effective C/Si ratio, and at low growth rate, the aluminum incorporation increases initially, levels off at a critical pressure, and continues to decrease below the critical pressure. The aluminum incorporation showed to be constant in a temperature range of 50degreesC. The highest atomic concentration of aluminum observed in this study was 3 x 10(17) and 8 x 10(18) cm(-3) in Si and C-face, respectively.

  • 17. Forsberg, U.
    et al.
    Danielsson, O.
    Henry, A.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Janzen, E.
    Nitrogen doping of epitaxial silicon carbide2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 236, no 03-jan, p. 101-112Article in journal (Refereed)
    Abstract [en]

    Intentional doping with nitrogen of 4H- and 6H-SiC has been performed using a hot-wall CVD reactor. The nitrogen doping dependence on the temperature, pressure, C/Si ratio, growth rate and nitrogen flow has been investigated. The nitrogen incorporation for C-face material showed to be C/Si ratio independent, whereas the doping decreased with increasing C/Si ratio for the Si-face material in accordance with the site-competition model. The nitrogen incorporation was constant in a temperature window of 75degreesC on Si-face material indicating a mass transport limited incorporation. Increasing the growth rate resulted in a decrease of nitrogen incorporation on Si-face but an increase on C-face material. Finally, a comparison between previously published results on cold-wall CVD-grown material and the present hot-wall-grown material is presented.

  • 18. Forsberg, U.
    et al.
    Henry, A.
    Danielsson, Ö.
    Linnarsson, M. K.
    KTH, School of Information and Communication Technology (ICT).
    Janzén, E.
    Influence of growth parameters on the nitrogen incorporation in 4H- And 6H-SiC epilayers grown by hot-wall chemical vapour deposition2001In: Materials Research Society Symposium Proceedings, San Francisco, CA, 2001, Vol. 680, p. 73-78Conference paper (Refereed)
    Abstract [en]

    We have investigated the nitrogen incorporation dependency on temperature, pressure, C/Si ratio and growth rate in a horizontal hot-wall CVD reactor. The incorporation mechanism for 4H- and 6H-SiC both for Si- and C-face material is presented. A comparison with previously published results in a cold-wall reactor is also made. © 2001 Materials Research Society.

  • 19. Forsberg, U.
    et al.
    Henry, A.
    KTH, School of Information and Communication Technology (ICT).
    Danielsson, Ö.
    Rorsman, N.
    Eriksson, J.
    Wahab, Q.
    Storasta, L.
    Linnarsson, M. K.
    Janzén, E.
    Growth and characterisation of 4H-SiC MESFET structures grown by hot-wall CVD2001In: Materials Research Society Symposium - Proceedings, Boston, MA, 2001, Vol. 640, p. H2.3.1-H2.3.6Conference paper (Refereed)
    Abstract [en]

    Metal semiconductor field effect transistor, MESFET, structures have been grown in a hot-wall CVD reactor. Using trimethylaluminium and nitrogen as dopant sources, p- and n-type epitaxial layers were grown on semi insulating substrates. A comprehensive characterization study of thickness and doping of these structures has been performed by using scanning electron microscopy, secondary ion mass spectrometry, capacitance-voltage measurements. Each technique is discussed concerning its advantage and disadvantage. Some transistor properties of MESFETs processed on the grown material are presented.

  • 20. Forsberg, U
    et al.
    Henry, A
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Janzen, E
    Photoluminescence study of CVD layers highly doped with nitrogen2000In: SILICON CARBIDE AND RELATED MATERIALS - 1999 PTS, 1 & 2, 2000, Vol. 338-3, p. 619-622Conference paper (Refereed)
    Abstract [en]

    From a systematic study of highly doped n-type 4H-SiC epilayers we observe a photoluminescence spectrum, which was previously associated with the recombination of a bound exciton at the neutral boron acceptor. Electrical measurements performed on these layers show clearly n-type conductivity. It was feasible to dope and measure reproducibly the layers from low 10(17) to mid 10(18) cm(-3). It was not possible to determine the doping from Capacitance Voltage measurements for the samples grown with the highest doping (>6.10(18) cm(-3)). However Secondary Ion Mass spectrometry did not reveal any boron impurities in the layers and shows good agreement with electrical measurements regarding the nitrogen concentration.

  • 21. Gabrysch, Markus
    et al.
    Majdi, Saman
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Linnarsson, Margareta K
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Schoner, Adolf
    Twitchen, Daniel
    Isberg, Jan
    Compensation in boron-doped CVD diamond2008Article in journal (Refereed)
    Abstract [en]

    Hall-effect measurements on single crystal boron-doped CVD diamond in the temperature interval 80-450 K are presented together with SIMS measurements of the dopant concentration. Capacitance-voltage measurements on rectifying Schottky junctions manufactured on the boron-doped structures are also presented in this context. Evaluation of the compensating donor (N-D) and acceptor concentrations (N-A) show that in certain samples very low compensation ratios (N-D/N-A below 10(-4)) have been achieved. The influence of compensating donors on majority carrier transport and the significance for diamond device performance are briefly discussed.

  • 22. Gislason, H. P.
    et al.
    Yang, B. H.
    Linnarsson, M.
    KTH, School of Information and Communication Technology (ICT).
    Properties of high-resistivity Li-diffused GaAs1992In: Semi-Insulating III-V Materials, 1992 Proceedings of the 7th Conference on, 1992, p. 55-60Conference paper (Refereed)
    Abstract [en]

    Not available

  • 23. GISLASON, HP
    et al.
    YANG, BH
    LINNARSSON, M
    KTH, School of Information and Communication Technology (ICT).
    SHIFTING PHOTOLUMINESCENCE BANDS IN HIGH-RESISTIVITY LI-COMPENSATED GAAS1993In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 47, p. 9418-9424Article in journal (Refereed)
    Abstract [en]

    It is shown that Li diffusion of GaAs can give rise to semi-insulating samples with electrical resistivity as high as 10(7) OMEGAcm in undoped, n-type, and p-type starting materials. The optical properties of the compensated samples are correlated with the depletion of free carriers caused by the Li diffusion. The radiative recombination of the Li-compensated samples is dominated by emissions with excitation-dependent peak positions that shift to lower energies with increasing compensation. The photoluminescence properties are characteristic of fluctuations of the electrostatic potential in strongly doped, compensated crystals.

  • 24. GISLASON, HP
    et al.
    YANG, BH
    PETURSSON, J
    LINNARSSON, M
    KTH, School of Information and Communication Technology (ICT).
    RADIATIVE RECOMBINATION IN N-TYPE AND P-TYPE GAAS COMPENSATED WITH LI1993In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 74, p. 7275-7287Article in journal (Refereed)
    Abstract [en]

    We report fundamental changes of the radiative recombination in a wide range of n-type and p-type GaAs after diffusion with the group-I element Li. These optical properties are found to be a bulk property and closely related to the electrical conductivity of the samples. In the Li-doped samples the radiative recombination is characterized by emissions with excitation-dependent peak positions which shift to lower energies with increasing degree of compensation and concentration of Li. These properties are shown to be in qualitative agreement with fluctuations of the electrostatic potential in strongly compensated systems. For Li-diffusion temperatures above 700-800-degrees-C semi-insulating conditions with electrical resistivity exceeding 10(7) OMEGA cm are obtained for all conducting starting materials. In this heavy Li-doping regime, the simple model of fluctuating potentials is shown to be inadequate for explaining the. experimental observations unless the number of charged impurities is reduced through complexing with Li. For samples doped with low concentrations of Li, on the other hand, the photoluminescence properties are found to be characteristic of impurity-related emissions.

  • 25. Grivickas, V.
    et al.
    Gulbinas, K.
    Jokubaviius, V.
    Sun, J. W.
    Karalinas, M.
    Kamiyama, S.
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Kaiser, M.
    Wellmann, P.
    Syväjärvi, M.
    Carrier lifetimes and influence of in-grown defects in N-B Co-doped 6H-SiC2014In: IOP Conference Series: Materials Science and Engineering, 2014, Vol. 56, no 1Conference paper (Refereed)
    Abstract [en]

    The thick N-B co-doped epilayers were grown by the fast sublimation growth method and the depth-resolved carrier lifetimes have been investigated by means of the free-carrier absorption (FCA) decay under perpendicular probe-pump measurement geometry. In some samples, we optically reveal in-grown carbon inclusions and polycrystalline defects of substantial concentration and show that these defects slow down excess carrier lifetime and prevent donor-acceptor pair photo luminescence (DAP PL). A pronounced electron lifetime reduction when injection level approaches the doping level was observed. It is caused by diffusion driven non-radiative recombination. However, the influence of surface recombination is small and insignificant at 300 K.

  • 26. Gulbinas, K.
    et al.
    Ščajev, P.
    Bikbajavas, V.
    Grivickas, V.
    Korolik, O. V.
    Mazanik, A. V.
    Fedotov, A. K.
    Jokubaviius, V.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Syväjärvi, M.
    Kamiyama, S.
    Raman scattering and carrier diffusion study in heavily Co-doped 6H-SiC layers2014In: IOP Conference Series: Materials Science and Engineering, 2014, Vol. 56, no 1Conference paper (Refereed)
    Abstract [en]

    Thick 6H-SiC epilayers were grown using the fast sublimation method on low-off-axis substrates. They were co-doped with N and B impurities of ≈1019 cm-3 and (4·1016- 5·1018) cm-3 concentration, respectively. The epilayers exhibited donor-acceptor pair (DAP) photoluminescence. The micro-Raman spectroscopic study exposed a compensated n-6H-SiC epilayer of common quality with some 3C-SiC inclusions. The compensation ratio of B through 200 μm thick epilayer varied in 20-30% range. The free carrier diffusivity was studied by transient grating technique at high injection level. The determined ambipolar diffusion coefficient at RT was found to decrease from 1.15 cm2/s to virtually 0 cm2/s with boron concentration increasing by two orders.

  • 27. Hallen, A
    et al.
    Janson, M S
    Osterman, J
    Zimmermann, U
    Linnarsson, M
    KTH, School of Information and Communication Technology (ICT).
    Kuznetsov, A
    Zhang, Y
    Persson, P O A
    Svensson, B G
    Implanted p(+)n-junctions in silicon carbide2003In: APPLICATION OF ACCELERATORS IN RESEARCH AND INDUSTRY, 2003, Vol. 680, p. 653-657Conference paper (Refereed)
    Abstract [en]

    Ion implantation is considered a key technology for the realisation of silicon carbide electronic devices. Here we will give an overview of the field and present some recent results of ion implanted 4H SiC epitaxial layers. Mainly Al ions of keV energies have been used at different fluence, flux and target temperature. The samples have been investigated by secondary ion mass spectrometry (SIMS), channeling Rutherford backscattering (RBS-c) and transmission electron microscopy (TEM), both as-implanted and after annealing up to 1900 degreesC. Also the electrical activation of Al-implanted and annealed material has been investigated by scanning spreading resistance microscopy (SSRM). The damage accumulation, monitored by RBS-c, is linear with ion fluence but depends strongly on implantation temperature and ion flux. Annealing at temperatures above 1700 degreesC is needed to remove the damage and to electrically activate implanted Al ions. At these high annealing temperatures, however, dislocation loops are formed that have a negative influence on device performance.

  • 28.
    Hallén, Anders.
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Janson, M. S.
    Kuznetsov, A. Y.
    Aberg, D.
    Linnarsson, Margareta K
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Persson, P. O.
    Carlsson, F. H. C.
    Storasta, L.
    Bergman, J. P.
    Sridhara, S. G.
    Zhang, Y.
    Ion implantation of silicon carbide2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 186, p. 186-194Article in journal (Refereed)
    Abstract [en]

    Ion implantation is an important technique for a successful implementation of commercial SiC devices. Much effort has also been devoted to optimising implantation and annealing parameters to improve the electrical device characteristics. However, there is a severe lack of understanding of the fundamental implantation process and the generation and annealing kinetics of point defects and defect complexes. Only very few of the most elementary intrinsic point defects have been unambiguously identified so far. To reach a deeper understanding of the basic mechanisms SiC samples have been implanted with a broad range of ions, energies, doses, etc., and the resulting defects and damage produced in the lattice have been studied with a multitude of characterisation techniques. In this contribution we will review some of the results generated recently and also try to indicate where more research is needed. In particular, deep level transient spectroscopy (DLTS) has been used to investigate point defects at very low doses and transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) are used for studying the damage build-up at high doses.

  • 29.
    Hallén, Anders
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Ion implantation technology for silicon carbide2016In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 306, p. 190-193Article in journal (Refereed)
    Abstract [en]

    Ion implantation is a key process technique for semiconductor materials, in particular silicon, for local tailoring of the semiconductor properties. The wide bandgap semiconductor silicon carbide (SiC) features outstanding material properties for high power and high temperature electronic devices, but the properties of SiC also make it difficult to manufacture and process the material. The development of implantation technology for SiC has therefore necessitated several changes, from mainstream silicon implantation technology. This paper will discuss the difficulties with implantation of SiC for manufacturing of electronic devices and also describe how the problems have been overcome, for instance by implantation at elevated temperatures and using high temperature post-implant annealing. (C) 2016 Elsevier B.V. All rights reserved.

  • 30.
    Hallén, Anders.
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Suchodolskis, Arturas
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Österman, John
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Abtin, L.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Annealing of Al implanted 4H silicon carbide2006In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T126, p. 37-40Article in journal (Refereed)
    Abstract [en]

    Al ions were implanted with multiple energies up to 250 keV at elevated temperatures in n-type 4H SiC epitaxial layers to reach a surface concentration of 1 x 10(20) cm(-3). These samples were then annealed at temperatures between 1500 and 1950 degrees C. A similar 4H SiC epitaxial sample was implanted by MeV Al ions to lower doses and annealed only at 200 and 400 degrees C. After annealing, cross-sections of the samples were characterized by scanning spreading resistance microscopy (SSRM). The results show that the resistivity of high-dose Al implanted samples has not reached a saturated value, even after annealing at the highest temperature. For the MeV Al implanted sample, the activation of Al has not yet started, but a substantial annealing of the implantation induced damage can be seen from the SSRM depth profiles.

  • 31.
    Hallén, Anders
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Usman, M.
    Suvanam, Sethu Saveda
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Henkel, Christoph
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Martin, David M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Passivation of SiC device surfaces by aluminum oxide2014In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 56, no 1, p. 012007-Article in journal (Refereed)
    Abstract [en]

    A steady improvement in material quality and process technology has made electronic silicon carbide devices commercially available. Both rectifying and switched devices can today be purchased from several vendors. This successful SiC development over the last 25 years can also be utilized for other types of devices, such as light emitting and photovoltaic devices, however, there are still critical problems related to material properties and reliability that need to be addressed. This contribution will focus on surface passivation of SiC devices. This issue is of utmost importance for further development of SiC MOSFETs, which so far has been limited by reliability and low charge carrier surface mobilities. Also bipolar devices, such as BJTs, LEDs, or PV devices will benefit from more efficient and reliable surface passivation techniques in order to maintain long charge carrier lifetimes. Silicon carbide material enables the devices to operate at higher electric fields, higher temperatures and in more radiation dense applications than silicon devices. To be able to utilize the full potential of the SiC material, it is therefore necessary to develop passivation layers that can sustain these more demanding operation conditions. In this presentation it will also be shown that passivation layers of Al2O3 deposited by atomic layer deposition have shown superior radiation hardness properties compared to traditional SiO2-based passivation layers.

  • 32. HELMFRID, S
    et al.
    ARVIDSSON, G
    WEBJORN, J
    LINNARSSON, M
    KTH, School of Information and Communication Technology (ICT).
    PIHL, T
    STIMULATED-EMISSION IN ER-TI-LINBO3 CHANNEL WAVE-GUIDES CLOSE TO 1.53-MU-M TRANSITION1991In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 27, p. 913-914Article in journal (Refereed)
    Abstract [en]

    Fabrication and characterisation of Er:Ti:LiNbO3 channel waveguides is reported. A lifetime of 2.4 +/- 0.2 ms has been measured for the 4I13/2 level. In a pump and probe experiment using a high power InGaAsP laser and a tunable DBR laser, a signal increase of 0.75 dB for a transmitted pump power of 4.8 mW was demonstrated.

  • 33. Henry, A
    et al.
    Forsberg, U
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Janzen, E
    Determination of nitrogen doping concentration in doped 4H-SiC epilayers by low temperature photoluminescence2005In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 72, p. 254-257Article in journal (Refereed)
    Abstract [en]

    A complete calibration of nitrogen concentration in doped 4H-SiC material is presented. This is done in the very large range of doping available today. i.e. from low 10(14) to 10(19) cm(-3). The samples are 4H-SiC films fabricated by hot-wall chemical vapour deposition. Low temperature photoluminescence is used as the experimental tool. For doping concentrations less than 8. 10(17) cm(-3), comparison between the intensity of various luminescence lines is used. whereas for doping hi,,her than 3 - 10(18) cm(-3) the energy position of an observed broad band allows the determination of the doping level.

  • 34. Henry, A
    et al.
    Magnusson, B
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Ellison, A
    Syvajarvi, M
    Yakimova, R
    Janzen, E
    Presence of hydrogen in SiC2001In: SILICON CARBIDE AND RELATED MATERIALS, ECSCRM2000, 2001, Vol. 353-356, p. 373-376Conference paper (Refereed)
    Abstract [en]

    An unexpected presence of hydrogen in 4H-SiC was revealed by the observation of hydrogen related lines in the low-temperature photoluminescence (LTPL) spectrum after secondary ion mass spectrometry (SIMS) measurements. The lines were not observed before SIMS. The high-energy ions during SIMS are proposed to break the boron-hydrogen bonds. This phenomenon is observable only for a certain impurity concentration in the material due to the competition of various recombination channels during the LTPL experiment.

  • 35. Janson, M.
    et al.
    Linnarsson, M. K.
    KTH, School of Information and Communication Technology (ICT).
    Hallen, A.
    Svensson, B. G.
    Dissociation of deuterium-defect complexes in ion-implanted epitaxial 4H-SiC1998In: Materials Research Society Symposium - Proceedings, San Francisco, CA, USA, 1998, Vol. 513, no Warrendale, PA, United States, p. 439-444Conference paper (Refereed)
    Abstract [en]

    Epitaxial layers of low doped 4H-SiC are implanted with 20 keV 2H+ ions to a dose of 1×1015 cm-2. The samples are subsequently annealed at temperatures ranging from 1040 to 1135 °C. Secondary ion mass spectrometry is used to obtain the concentration versus depth profiles of the atomic deuterium in the samples. It is found that the concentration of implanted deuterium decreases rapidly in the samples as a function of anneal time. The experimental data are explained by a model where the deuterium migrates rapidly and becomes trapped and de-trapped at implantation-induced defects which exhibit a slightly shallower depth distribution than the implanted deuterium ions. Computer simulations using this model, in which the damage profile is taken from Monte Carlo simulations and the surface is treated as a perfect sink for the diffusing deuterium atoms, are performed with good results compared to the experimental data. The complexes are tentatively identified as carbon-deuterium at a Si-vacancy and a dissociation energy (ED) of approximately 4.9 eV is extracted for the deuterium-vacancy complexes.

  • 36. Janson, M S
    et al.
    Hallen, A
    Godignon, P
    Kuznetsov, A Y
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Morvan, E
    Svensson, B G
    Channeled implants in 6H silicon carbide2000In: SILICON CARBIDE AND RELATED MATERIALS - 1999 PTS, 1 & 2, 2000, Vol. 338-3, p. 889-892Conference paper (Refereed)
    Abstract [en]

    Implants of MeV B-11, Al-27 and Ga-69 into the <0001> channel of 6H-SiC have been performed and concentration versus depth profiles have been obtained utilizing secondary ion mass spectrometry (SIMS). The experiment shows that the deepest channeled Ga ions reach a depth of 6.6 mum, which is 4 times deeper than the projected range of a random angle implantation, while the deepest channeled B ions only exceed the random projected range by 40%. Measurements at several implantation fluences show that implantation induced damage quench the deep channeling at fluences around 2 and 10x10(13) cm(-2) for Al and Ga, respectively, while only a minor fluence dependence is found in the B implants at fluences up to 2.6x10(14) cm(-2). The ion mass dependence of these effects is explained by the electronic to nuclear stopping ratios. Monte Carlo simulations of the channeling implants have also been performed and good agreements are found between simulations and experimental data.

  • 37.
    Janson, M S
    et al.
    KTH, Superseded Departments, Electronics.
    Hallén, Anders
    KTH, Superseded Departments, Electronics.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Electronics.
    Nordell, Nils
    KTH, Superseded Departments, Electronics.
    Karlsson, S
    Svensson, B G
    Dissociation energy of the passivating hydrogen-aluminum complex in 4H-SiC2001In: Materials Science Forum, 2001, Vol. 353-356, p. 427-430Conference paper (Other academic)
    Abstract [en]

    The thermal stability of the passivating hydrogen-aluminum complex ((HAl)-H-2) in 4H-silicon carbide has been studied by determining the effective diffusion constant for hydrogen in an AI-doped epitaxial layer. Assuming a complex comprised of one H-2 and one AI acceptor ion, the extracted diffusivities provide the dissociation frequency of the complex. The extracted frequencies cover three orders of magnitude and yield a close to perfect fit to an Arrhenius equation with the extracted dissociation energy for the (HAl)-H-2-complex equal to 1.66 (+/-0.05) eV and a pre-exponential attempt frequency nu (0) = 1.7x10(13) s(-1) in good agreement with the expected value for a first order dissociation process.

  • 38. Janson, M. S.
    et al.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Linnarsson, Margareta K
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Hydrogen diffusion, complex formation, and dissociation in acceptor-doped silicon carbide2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, no 19Article in journal (Refereed)
    Abstract [en]

    The diffusion of deuterium (H-2) in B and Al doped 4H and 6H silicon carbide (SiC) has been studied in detail by secondary ion mass spectrometry. From H-2 depth profiles, following trap limited diffusion with negligible complex dissociation, an effective capture radius for the formation of H-2-B complexes (at 460 degreesC) is determined to R-HB = (21+/-4) Angstrom. This value is in good agreement with that expected for a Coulomb force assisted trapping mechanism. At annealing conditions where dissociation is non-negligible, the H-2 diffusion follows Fick's law with a constant effective diffusivity, from which the complex dissociation frequencies nu are determined. The extracted values of nu cover three orders of magnitude and exhibit a close to perfect Arrhenius temperature dependence for both H-2-B and H-2-Al complexes. The large difference between the extracted complex dissociation energies, E-d(HB)=(2.51+/-0.04) eV and E-d(HA1)=(1.61+/-0.02) eV, suggests that the atomic configurations of the two complexes are significantly different. The corresponding extracted dissociation attempt frequencies, nu (HB)(0)=(1.2+/-0.7) x 10(13) s(-1) and nu (HA1)(0)=(0.7+/-0.3) x 10(13) s(-1), are very close to the characteristic oscillation frequency of the SiC lattice, nu (SiC)(lattice)=1.6 x 10(13) s(-1). This is strong evidence for the assumption of a first order dissociation process. No difference between 4H- and 6H-SiC has been observed.

  • 39. Janson, M. S.
    et al.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Linnarsson, Margareta K
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Hydrogen-boron complex formation and dissociation in 4H-silicon carbide2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, no 04-jan, p. 257-262Article in journal (Refereed)
    Abstract [en]

    The diffusion of deuterium (H-2) in p-type 4H-silicon carbide (SiC) has been studied in detail by secondary ion mass spectrometry. An effective capture radius for the formation of H-2-B complexes at 460 degreesC is determined to R-HB = (21 +/- 4) A. This value is in good agreement with that expected for a coulomb force-assisted trapping mechanism. At higher temperatures, the H-2 diffusion follows Fick's law with a constant effective diffusivity from which the complex dissociation frequencies nu (HB) are determined. The frequencies exhibit an Arrhenius temperature dependence over the three orders of magnitude covered by the extracted nu (HB). The complex dissociation energy is determined to E-d(HB) = (2.51 +/- 0.04) eV which is 0.9 eV larger than the corresponding value for the H-2-Al complex, suggesting that the atomic configurations for the two complexes are significantly different. The extracted dissociation attempt frequency, nu (HB)(0) = (1.2 +/- 0.7) x 10(13) s(-1) is very close to the characteristic oscillation frequency of the SiC lattice, nu (SiC)(lattice) = 1.6 x 10(13) s(-1). In addition, H-2 diffusion in an epitaxial AI multilayer structure demonstrates the influence of internal electric fields on the H-2 diffusion in p-type SiC.

  • 40. Janson, M S
    et al.
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Christensen, J S
    Leveque, P
    Kuznetsov, A Y
    Radamson, H H
    Hallen, A
    Nylandsted-Larsen, A
    Svenssen, B G
    Diffusion of dopants and impurities in device structures of SiC, SiGe and Si2001In: DIFFUSIONS IN MATERIALS: DIMAT2000, PTS 1 & 2, 2001, Vol. 194-1, p. 597-609Conference paper (Refereed)
    Abstract [en]

    Silicon Carbide (SiC) has a high thermal stability and for most elements temperatures in excess of 2000 degreesC are anticipated to reach reasonable diffusivities (greater than or equal to 10(-13) cm(2)/s). We demonstrate, however, that light elements, like hydrogen and lithium, exhibit a considerable mobility already at less than or equal to 400 degreesC, Technologically, the principal interest in these light elements arises because of their ability to electrically passivate shallow acceptors and donors as well as deep level defects in common semiconductors (SiC, Si, GaAs). Indeed, for both hydrogen and lithium the diffusion kinetics is shown to be strongly affected by trapping and de-trapping at boron impurities in the SiC layers. Evidence is also provided that hydrogen migrates as a positively charged ion in p-type SiC. Furthermore, similar to that in crystalline silicon, transient enhanced diffusion of ion-implanted boron is observed in SiC. The initial boron diffusivity during postimplant annealing at 1600 degreesC is enhanced by more than two orders of magnitude compared to equilibrium conditions. For Silicon Germanium (SiGe) diffusion of the n-type dopants Sb and P is studied. Comparing results from strained and relaxed SiGe layers annealed under inert and oxidizing conditions it is unambiguously shown that the diffusion of Sb is almost exclusively mediated by vacancies. On the other hand, P diffusion is predominantly assisted by Si self-interstitials and in this case compositional and strain effects in the SiGe layers are competing.

  • 41. Janson, M S
    et al.
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Hallen, A
    Svensson, B G
    Range distributions of implanted ions in silicon carbide2002In: SILICON CARBIDE AND RELATED MATERIALS 2001, PTS 1 AND 2, PROCEEDINGS, 2002, Vol. 389-3, p. 779-782Conference paper (Refereed)
    Abstract [en]

    The first four distribution moments (R-P, DeltaR(p), gamma and beta) of 113 experimental single energy ion implantations into silicon carbide (SiC) have been assembled to form the base for an empirical ion implantation simulator using Pearson frequency functions. The studied ions are H-1, H-2, Li-7, B-11, N-14, O-11, Al-27, P-31, and As-75, and the implantation energies range from 0.5 keV to 4 MeV. Thirty-nine of these implantations have been implanted, measured, and analyzed in the present study while the remaining implantation data were gathered from the literature. Furthermore, 16 additional implantations were simulated - using a new Binary Collision Approximation (BCA) code for crystalline materials - to fill up the missing energies for ions with limited experimental data. The extracted range data are presented as tabulated fitting constants to analytical functions of the distribution moments versus implantation energy.

  • 42. Janson, M. S.
    et al.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hallen, A. A.
    Svensson, B. G.
    Ion implantation range distributions in silicon carbide2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 11, p. 8903-8909Article in journal (Refereed)
    Abstract [en]

    The first to fourth order distribution moments, R-p, DeltaR(p), gamma, and beta, of 152 single energy H-1, H-2, Li-7, B-11, N-14, O-16, Al-27, P-31, Ga-69, and As-75 implantations into silicon carbide (SiC) have been assembled. Fifty of these implantations have been performed and analyzed in the present study while the remaining mplantation data was compiled from the literature. For ions with a limited amount of experimental data, additional implantations were simulated using a recently developed binary collision approximation code for crystalline materials. Least squares fits of analytical functions to the distribution moments versus implantation energy provide the base for an empirical ion implantation simulator using Pearson frequency functions.

  • 43. Janson, M. S.
    et al.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hallén, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Nordell, N.
    Bleichner, H.
    Transient enhanced diffusion of implanted boron in 4H-silicon carbide2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 11, p. 1434-1436Article in journal (Refereed)
    Abstract [en]

    Experimental evidence is given for transient enhanced diffusion of boron (B) in ion-implanted silicon carbide (SiC). The implanted B is diffusing several mu m into the samples when annealed at 1600 and 1700 degrees C for 10 min, but the in-diffused tails remain unaffected when the annealing times are increased to 30 min at the same temperatures. A lower limit of the effective B diffusivity at 1600 degrees C is determined to 7x10(-12) cm(2)/s, which is 160 times larger than the equilibrium B diffusivity given in the literature.

  • 44.
    Janson, Martin S.
    et al.
    KTH, Superseded Departments, Electronics.
    Hallén, Anders
    KTH, Superseded Departments, Electronics.
    Linnarsson, Margareta K
    KTH, Superseded Departments, Electronics.
    Svensson, Bengt Gunnar
    KTH, Superseded Departments, Electronics.
    Nordell, Nils
    IMC, Sweden.
    Karlsson, S.
    Electric-field-assisted migration and accumulation of hydrogen in silicon carbide2000In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 61, no 11, p. 7195-7198Article in journal (Refereed)
    Abstract [en]

    The diffusion of deuterium (H-2) in epitaxial 4H-SiC layers with buried highly Al-acceptor doped regions has been studied by secondary ion mass spectrometry. H-2 was introduced in the near surface region by the use of 20-keV implantation after which the samples were thermally annealed. As a result, an anomalous accumulation of H-2 in the high doped layers was observed. To explain the accumulation kinetics, a model is proposed where positively charged H-2 ions are driven into the high doped layer and become trapped there by the strong electric field at the edges. This effect is important for other semiconductors as well, since hydrogen is a common impurity present at high concentrations in many semiconductors.

  • 45.
    Janson, Martin S.
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hallén, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, Bengt G.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Electronic stopping cross sections in silicon carbide for low-velocity ions with 1 <= Z(1)<= 152004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 1, p. 164-169Article in journal (Refereed)
    Abstract [en]

    The mean projected range R-p for a large number of H-1, H-2, Li-7, B-11, N-14, O-16, Al-27, and P-31 implantations into SiC with ion energies ranging from 0.5 keV to 4 MeV are investigated. From the R-p data the electronic stopping cross sections S-e are extracted. A plot of the extracted S-e at a fixed velocity-below the Fermi velocity of the target valence electrons-versus the ion atomic number Z(1) reveals a local maximum around Z(1)=7. Furthermore, in this velocity regime a slower than velocity-proportional energy dependence, S(e)proportional toE(0.30)-E-0.45, is found for ions with 1less than or equal toZ(1)less than or equal to8, while Al-27 and P-31 exhibit an energy dependence just above velocity-proportionality: S(e)proportional toE(0.52), for both ions. These finding are in good qualitative agreement with the low-velocity electronic stopping behavior previously reported for carbon targets.

  • 46.
    Janson, Martin S.
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hallén, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, Bengt G.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Achtziger, N.
    Uneus, L.
    Spetz, A. Lloyd
    Forsberg, U.
    Hydrogen in the wide bandgap semiconductor silicon carbide2004In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T108, p. 99-112Article in journal (Refereed)
    Abstract [en]

    In this paper we give a review of our recent results related to the incorporation of hydrogen (H) in silicon carbide (SiC) and its interaction with acceptor doping atoms and implantation induced defects. Hydrogen is an abundant impurity in the growth of epitaxial SiC since it is present in the precursor gases and since H-2 is used as the carrier gas. High concentrations of hydrogen are indeed incorporated into highly doped p-type epi-layers and it is shown that the main source is the carrier gas. Furthermore, it is revealed that the entire substrate becomes homogeneously filled with hydrogen during growth and that this hydrogen is more thermally stable than that in the epi-layer. Incorporation of hydrogen from an H-2 ambient, at temperatures considerably lower than those used for epitaxy, is also demonstrated in p-type samples coated with a catalytic metal film. This effect is most likely the cause for the increased series resistance observed in p-type SiC Schottky sensor devices using a catalytic metal gate after annealing at 600 degrees C in a H-2 containing ambient. Hydrogen is found to passivate the acceptors Al and B by forming electrically neutral H-acceptor complexes. Unlike in Si and GaAs, the two H-acceptor complexes in SiC exhibit very different dissociation energies, suggesting that the atomic configurations of the complexes are significantly different. The migration of mobile hydrogen in the presence of externally applied, or internal built-in, electric fields further reveals that hydrogen is present as H+ in p-type SiC. Finally, the redistribution and subsequent out-diffusion of low energy implanted H-1 and H-2 is investigated. Two annealing phases for the redistribution are observed, and the activation energies for the processes are extracted.

  • 47. Kaiser, M.
    et al.
    Hupfer, T.
    Jokubavicus, V.
    Schimmel, S.
    Syväjärvi, M.
    Ou, Y.
    Ou, H.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Wellmann, P.
    Polycrystalline SiC as source material for the growth of fluorescent SiC layers2013In: Silicon Carbide And Related Materials 2012, Trans Tech Publications Inc., 2013, Vol. 740-742, p. 39-42Conference paper (Refereed)
    Abstract [en]

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.

  • 48. Kaiser, M.
    et al.
    Schimmel, S.
    Jokubavicius, V.
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Ou, H.
    Syväjärvi, M.
    Wellmann, P.
    Nucleation and growth of polycrystalline SiC2014In: IOP Conference Series: Materials Science and Engineering, 2014, no 1Conference paper (Refereed)
    Abstract [en]

    The nucleation and bulk growth of polycrystalline SiC in a 2 inch PVT setup using isostatic and pyrolytic graphite as substrates was studied. Textured nucleation occurs under near-thermal equilibrium conditions at the initial growth stage with hexagonal platelet shaped crystallites of 4H, 6H and 15R polytypes. It is found that pyrolytic graphite results in enhanced texturing of the nucleating gas species. Reducing the pressure leads to growth of the crystallites until a closed polycrystalline SiC layer containing voids with a rough surface is developed. Bulk growth was conducted at 35 mbar Ar pressure at 2250°C in diffusion limited mass transport regime generating a convex shaped growth form of the solid-gas interface leading to lateral expansion of virtually [001] oriented crystallites. Growth at 2350°C led to the stabilization of 6H polytypic grains. The micropipe density in the bulk strongly depends on the substrate used.

  • 49. Kakanakova-Georgieva, A.
    et al.
    Yakimova, R.
    Gueorguiev, G. K.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Syvajarvi, M.
    Janzen, E.
    Kinetics of residual doping in 4H-SiC epitaxial layers grown in vacuum2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 240, no 04-mar, p. 501-507Article in journal (Refereed)
    Abstract [en]

    Investigation on residual Al, B, and N co-doping of 4H-SiC epitaxial layers is reported. The layers were produced by sublimation epitaxy in Ta growth cell environment at different growth temperatures and characterized by secondary ion mass spectrometry. The vapor interaction with Ta was considered through calculations of cohesive energies of several Si-, Al-, B-, and N-containing vapor molecules and also of diatomic Ta-X molecules. An analysis of kinetic mechanisms responsible for impurity incorporation is performed. Among residuals, B exhibits a stronger incorporation dependence on temperature and growth at lower temperatures can favor B decrease in the layers. Under the growth conditions in this study (Ta environment and presence of attendant Al and N), B incorporation is assisted by Si2C vapor molecule. Boron tends to occupy carbon sites at higher temperatures, i.e. higher growth rates.

  • 50. Kakanakova-Georgieva, A.
    et al.
    Yakimova, R.
    Henry, A.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Syvajarvi, M.
    Janzen, E.
    Cathodoluminescence identification of donor-acceptor related emissions in as-grown 4H-SiC layers2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 5, p. 2890-2895Article in journal (Refereed)
    Abstract [en]

    A comparative analysis of cathodoluminescence spectra in 4H-SiC layers with different N, Al, and B content is reported. The layers were produced by sublimation epitaxy and residual impurity concentrations were determined by secondary ion mass spectrometry. Epilayers doped with B in a wide concentration range, 5x10(15)-3x10(18) cm(-3), were achieved. Evidence of N, Al, and B related emissions by cathodoluminescence experiments is presented. Differences in the luminescence emitted by the layers are established that are attributed to different B content and impurity cooperation. The characteristics of broad green emission, originating from B-related centers, at 4.6 K, 300 K, as well as in high temperature annealed layers are discussed. The experimental results suggest that boron is involved in more than one deep acceptor center.

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