| 1. |
- Achtziger, N, et al.
(författare)
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Hydrogen passivation of silicon carbide by low-energy ion implantation
- 1998
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 73, s. 945-947
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Achtziger, N, et al.
(författare)
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Mobility passivating effect and thermal stability of hydrogen in silicon carbide
- 1998
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Ingår i: Physica status solidi. B, Basic research. - 0370-1972 .- 1521-3951. ; 210, s. 395-399
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Janson, M., et al.
(författare)
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Dissociation of deuterium-defect complexes in ion-implanted epitaxial 4H-SiC
- 1998
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Ingår i: Materials Research Society Symposium - Proceedings. - San Francisco, CA, USA. ; , s. 439-444
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 4. |
- Linnarsson, M, et al.
(författare)
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Electronic structure of the GaAs:Mn-Ga center
- 1997
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 55, s. 6938-6944
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Tidskriftsartikel (refereegranskat)abstract
- The excitation spectrum of the O.11-eV Mn acceptor in GaAs has been thoroughly investigated by uniaxial stress and Zeeman fourier transform infrared spectroscopy. The results give strong evidence for the 3d(5) + shallow hole model for the Mn-0 center. The deformation potentials as well as the g values determined for the hole are in close agreement with those previously reported for the 1S(3/2)(Gamma(8)) State for shallow accepters in GaAs. All experimental results are in accordance with a J = 1 ground-state level derived from exchange coupling of the shallow 1S(3/2)(Gamma(8)) hole and the S = 5/2 Mn- core. A splitting between J = 2 and J = 1 levels in the range from 9 to 12 meV is inferred and is considerably larger than the 2-3 meV splitting previously suggested.
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| 5. |
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| 6. |
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| 7. |
- Linnarsson, M K, et al.
(författare)
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Deuterium incorporation in acceptor doped epitaxial layers of 6H-SiC
- 1998
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Ingår i: SILICON CARBIDE, III-NITRIDES AND RELATED MATERIALS, PTS 1 AND 2. ; , s. 761-764
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Konferensbidrag (refereegranskat)abstract
- Deuterium is introduced in boron doped epitaxial layers of 6H-SiC by implantation of 30 keV H-2(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum at 700 degrees C/16h, 800 degrees C/4h and 900 degrees C/4h. Using depth profiling by secondary ion mass spectrometry (SIMS), the distributions of deuterium at different levels of boron doping are studied. The deuterium concentration correlates with the boron concentration and at a level of similar to 10(18) cm(-3) a ratio H-2/B-11 larger than 0.5 is obtained. From capacitance-voltage (CV) measurements a decrease in the electrical carrier concentration by 50% is revealed after deuterium diffusion at 800 degrees C/4h. At 900 degrees C passivation of the boron accepters ceases but the H-2 atoms are still confined to the boron-doped regions and display no long range migration.
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| 8. |
- Linnarsson, M K, et al.
(författare)
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Diffusion of light elements in 4H-and 6H-SiC
- 1999
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Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 61-2, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Deuterium and lithium were introduced in p-type SiC by implantation of 20 keV H-2(+) or 30 keV Li-7(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum in the temperature range 400-700 degrees C for 0.25 to 16 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium and the lithium distribution after heat treatments. Both deuterium and lithium readily decorate the bombardment-induced defects in the vicinity of the ion implantation profile and they are also trapped, most likely by residual boron impurities, during diffusion into the bulk. An effective diffusion coefficient, reflecting the dissociation of trapped lithium, with an activation energy of 2.1 eV is extracted for lithium diffusion in p-type 6H SIG. Furthermore, a capture radius for trapping (most likely by boron) of deuterium is estimated as 10 Angstrom. (C) 1999 Elsevier Science S.A. All rights reserved.
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| 9. |
- Morvan, E, et al.
(författare)
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Channeling implantations of Al+ into 6H silicon carbide
- 1999
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 74, s. 3990-3992
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Tidskriftsartikel (refereegranskat)abstract
- A strong channeling effect of Al+ ions implanted into crystalline SiC has been observed by Monte Carlo simulations and experiments especially designed to demonstrate this phenomenon have been performed. Depth distributions of implanted Al were measured for on- and controlled off-axis Al implantations using secondary ion mass spectrometry (SIMS). Much deeper and wider profiles are obtained for the on-axis implantations as compared to off-axis implants. For higher doses, the experiment also reveals the growth of an intermediate peak slightly deeper than the random peak. The origin of the intermediate peak can be understood by combining SIMS results with Monte Carlo simulations, which motivates the development of advanced simulation tools for the ion implantation process in SiC. (C) 1999 American Institute of Physics. [S0003-6951(99)01426-6].
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| 10. |
- Svensson, B G, et al.
(författare)
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SIMS analysis of epitaxial layers for power- and micro-electronics
- 1998
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 136, s. 1034-1039
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Tidskriftsartikel (refereegranskat)abstract
- This paper gives an overview of recent secondary ion mass spectrometry (SIMS) studies of impurities and dopants in epitaxial layers of silicon and 6H silicon carbide (SiC). Detection limits in the 10(12) cm(-3) range are demonstrated for transition metal impurities like Ti in SiC. Hydrogen is found to be mobile in SiC at temperatures in excess of 600 degrees C despite strong trapping by defects and dopant atoms, and the effective diffusion coefficient exhibits an activation energy of similar to 3.5 eV. In epitaxially grown Si layers, containing Ge delta distributions, profile broadening and shift during sputtering by Ar+ ions are accurately described by recoil mixing. For O-2(divided by) ions oxide formation and surface swelling must also be considered. Further, at elevated sample temperature Ge is found to segregate out of the SiO2 surface layer formed during oxygen bombardment, consistent with a larger heat of oxide formation for Ge than Si and a high enough mobility in SiO2. (C) 1998 Elsevier Science B.V.
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