| 1. |
- Averkiev, N S, et al.
(author)
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Spin relaxation in asymmetrical heterostructures
- 2002
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In: Semiconductors (Woodbury, N.Y.). - : Springer Science Business Media. - 1063-7826 .- 1090-6479. ; 36:1, s. 91-97
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Journal article (peer-reviewed)abstract
- Electron spin relaxation by the Dyakonov-Perel mechanism is investigated theoretically in asymmetrical III-V heterostructures. Spin relaxation anisotropy for all three dimensions is demonstrated for a wide range of structural parameters and temperatures. Dependences of spin relaxation rates are obtained both for a GaAs-based heterojunctions and triangular quantum wells. The calculations show a several-orders-of-magnitude difference between spin relaxation times for heterostructure parameters realized in experiments.
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| 2. |
- Davydov, S.Yu., et al.
(author)
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A Simple Model for Calculating the Growth Rate of Epitaxial Layers of Silicon Carbide in Vacuum
- 2004
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In: Semiconductors (Woodbury, N.Y.). - : American Institute of Physics (AIP). - 1063-7826 .- 1090-6479. ; 38:2, s. 150-152
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Journal article (peer-reviewed)abstract
- The temperature dependence of the growth rate of epitaxial layers of silicon carbide in vacuum was calculated within the simple model based on the Hertz-Knudsen equation, taking into account the temperature-dependent sticking coefficient. The calculation results fit the experimental data well. © 2004 MAIK "Nauka/Interperiodica".
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| 3. |
- Kalinina, E. V., et al.
(author)
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Effect of irradiation with fast neutrons on electrical characteristics of devices based on CVD 4H-SiC epitaxial layers
- 2003
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In: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 37:10, s. 1229-1233
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Journal article (peer-reviewed)abstract
- The effect of irradiation with 1-MeV neutrons on electrical properties of Al-based Schottky barriers and p(+)-n-n(+) diodes doped by ion-implantation with Al was studied; the devices were formed on the basis of high-resistivity, pure 4H-SiC epitaxial layers possessing n-type conductivity and grown by vapor-transport epitaxy. The use of such structures made it possible to study the radiation defects in the epitaxial layer at temperatures as high as 700 K. Rectifying properties of the diode structures were no longer observed after irradiation of the samples with neutrons with a dose of 6 x 10(14) cm(-2); this effect is caused by high (up to 50 GOmega) resistance of the layer damaged by neutron radiation. However, the diode characteristics of irradiated p(+)-n-n(+) structures were partially recovered after an annealing at 650 K.
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| 4. |
- Kalinina, E. V., et al.
(author)
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Optical and electrical properties of 4H-SiC irradiated with fast neutrons and high-energy heavy ions
- 2004
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In: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 38:10, s. 1187-1191
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Journal article (peer-reviewed)abstract
- Photoluminescence and deep-level transient spectroscopy are used to study the effect of irradiation with fast neutrons and high-energy Kr (235 MeV) and Bi (710 MeV) ions on the optical and electrical properties of high-resistivity high-purity n-type 4H-SiC epitaxial layers grown by chemical vapor deposition. Electrical characteristics were studied using the barrier structures based on these epitaxial layers: Schottky barriers with Al and Cr contacts and p(+)-n-n(+) diodes fabricated by Al ion implantation. According to the experimental data obtained, neutrons and high-energy ions give rise to the same defect-related centers. The results show that, even for the extremely high ionization density (34 keV/nm) characteristic of Bi ions, the formation of the defect structure in SiC single crystals is governed by energy losses of particles due to elastic collisions.
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| 5. |
- Lebedev, A.A., et al.
(author)
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Radiation hardness of wide-gap semiconductors (using the example of silicon carbide)
- 2002
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In: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 36:11, s. 1270-1275
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Journal article (peer-reviewed)abstract
- Results obtained in studying the effect of ionizing radiation on epitaxial layers and devices based on silicon carbide (SiC) are considered. It is shown that, in investigations of wide-gap semiconductors (WGS), account should be taken of how the rate of removal of mobile charge carriers - the standard parameter in determining the radiation hardness of a material - depends on temperature. The use of data obtained only at room temperature may lead to an incorrect assessment of the radiation hardness of WGS. A conclusion is made that the WGS properties combine, on the one hand, high radiation hardness of high-temperature devices based on these semiconductors and, on the other, the possibility of effective radiation-induced doping (e.g., for obtaining semi-insulating local regions in a material at room temperature). © 2002 MAIK "Nauka/Interperiodica".
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| 6. |
- Lebedev, Alexander, et al.
(author)
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Structural defects and deep-level centers in 4H-SiC epilayers grown by sublimational epitaxy in vacuum
- 2000
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In: Semiconductors (Woodbury, N.Y.). - 1063-7826 .- 1090-6479. ; 34:10, s. 1133-1136
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Journal article (peer-reviewed)abstract
- The parameters of deep-level centers in lightly doped 4H-SiC epilayers grown by sublimational epitaxy and CVD were investigated. Two deep-level centers with activation energies E-c - 0.18 eV and E-c - 0.65 eV (Z1 center) were observed and tentatively identified with structural defects of the SiC crystal lattice. The Z1 center concentration is shown to fall with decreasing uncompensated donor concentration N-d - N-a in the layers. For the same N-d - N-a, the Z1 center concentration is lower in layers with a higher dislocation density. (C) 2000 MAIK "Nauka/Interperiodica".
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| 7. |
- Litvinov, VV, et al.
(author)
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Local vibrational modes of the oxygen-vacancy complex in germanium
- 2002
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In: Semiconductors. - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 36:6, s. 621-624
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Journal article (peer-reviewed)abstract
- Infrared absorption of n- and p-Ge crystals enriched with O-16 and/or O-18 isotopes was studied after irradiation with 6-MeV electrons. Absorption spectra were measured at 10 and 300 K. Along with known bands characteristic of oxygen-containing defects, new lines at 669, 944, and 990 cm(-1) were detected. These bands are annealed at temperatures of 120-140degreesC; the band at 621 cm(-1), previously related to the vacancy-oxygen complex in Ge, is simultaneously annealed. The bands at 621 and 669 cm(-1) showed identical temperatures (10 --> 300 K) and oxygen isotope (O-16 --> O-18) shifts. These bands were found to correspond to various charge states of a defect with an energy level near E-v = 0.25 +/- 0.03 eV. It is assumed that such a defect is the vacancy-oxygen complex (A center). The weak bands at 944 and 990 cm(-1) were identified as combinations of asymmetric stretching modes at 621 and 669 cm(-1) with a symmetric one at 320 cm(-1) for neutral and negative charge states of the A center, respectively.
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| 8. |
- Strokan, N.B., et al.
(author)
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Radiation resistance of transistor- and diode-type SiC detectors irradiated with 8-MeV protons
- 2004
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In: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 38:7, s. 807-811
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Journal article (peer-reviewed)abstract
- Nuclear-particle detectors based on SiC with a structure composed of an n+-type substrate, a p-type epitaxial layer, and a Schottky barrier are studied. Structures with a ~10-µm-thick 6H-SiC layer exhibit transistor properties, whereas those with a ~30-µm-thick 4H-SiC layer exhibit diode properties. It is established that a more than tenfold amplification of the signal is observed in the transistor-type structure. The amplification is retained after irradiation with 8-MeV protons with a dose of at least 5 × 1013 cm-2, in this case, the resolution is =10%. Amplification of the signal was not observed in the structures of diode type. However, there were diode-type detectors with a resolution of ˜3%, which is acceptable for a number of applications, even after irradiation with the highest dose of 2 × 1014 cm-2. © 2004 MAIK "Nauka/Interperiodica".
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| 9. |
- Strokan, N.B., et al.
(author)
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Silicon carbide transistor structures as detectors of weakly ionizing radiation
- 2003
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In: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 37:1, s. 65-69
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Journal article (peer-reviewed)abstract
- SiC-based nuclear radiation detectors figured prominently in the very first attempts of the 1960s to replace gas in ionization chambers with a more condensed semiconducting medium. However, the dynamics of improvement of SiC in those years was markedly inferior to the progress made in the development of competing materials. This study continues with the investigation of triode detector structures based on "pure" SiC films. It is established that for weakly ionizing radiation (as also in the case of strongly ionizing alpha particles) the signal is amplified by no less than a factor of several tens. This allows SiC films with a thickness of about 10 µm to be used to detect penetrating radiation, e.g., X-rays, since the effective thickness of the films is on the order of hundreds of micrometers. © 2003 MAIK "Nauka/Interperiodica".
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| 10. |
- Tkachman, M.G., et al.
(author)
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Phonon-assisted exciton luminescence in GaN layers grown by MBE and chloride-hydride VPE
- 2003
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In: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 37:5, s. 532-536
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Journal article (peer-reviewed)abstract
- Optical properties of GaN layers grown by the molecular-beam epitaxy (MBE) and chloride-hydride vapor-phase epitaxy (CHVPE) have been studied, and the quality of two types of samples has been compared. The photoluminescence spectra have an excitonic nature for both types of layers. To determine precisely the nature of exciton transitions, the reflectance spectra were studied. A key point was the investigation of phonon-assisted exciton luminescence, which provides information on the density distribution of the exciton states. Temperature dependences of the exciton transition energy and the ratio of intensities of one- and two-phpnon replicas were studied. The high quality of both types of layers has been confirmed, though the concentration of acceptors in MBE-grown samples is higher than in CHVPE samples. © 2003 MAIK "Nauka/Interperiodica".
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