Papers by Author: Vitalii V. Kozlovski

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Authors: Alexander A. Lebedev, S.V. Belov, Marina G. Mynbaeva, Anatoly M. Strel'chuk, Elena V. Bogdanova, Yu.N. Makarov, A.S. Usikov, Sergey Kurin, I.S. Barash, Alexander D. Roenkov, Vitalii V. Kozlovski
Abstract: Schottky-barrier diodes with a diameter of ~10 μm are fabricated on n-GaN epitaxial films grown by hydride vapor-phase epitaxy (HVPE) on sapphire substrates. The changes in the parameters of the diodes under irradiation with 15 MeV protons are studied. The carrier rate was found to be 130-145 cm-1. The linear nature of the dependence N = F (D) (N is carrier concentration, and D, the irradiation dose) shows that compensation of the material is associated with transition of electrons from shallow donors to deep acceptor levels which are related to primary radiation defects.
Authors: Alexander A. Lebedev, Klavdia S. Davydovskaya, Anatoly M. Strel'chuk, Andrey N. Yakimenko, Vitalii V. Kozlovski
Abstract: The change in the current-voltage characteristics and in Nd-Na values in the base of 4H-SiC Schottky diodes and JBS diodes under irradiation with 0.9 MeV electrons and 15 MeV protons has been studied. The carrier removal rate for the diodes irradiated with electrons was 0.07-0.15 cm-1, and that in the case of protons, 50-70 cm-1. It was shown that the devices under study retain rectifying current-voltage characteristics up to electron doses of ~1017 cm-2. It was found that the radiation resistance of the SiC-based devices significantly exceeds that of silicon p-i-n-diodes with similar breakdown voltages. The simultaneous effect of high temperature and proton irradiation on the characteristics of 4H-SiC pn structures was examined.
Authors: Vitalii V. Kozlovski, Alexander A. Lebedev, Elena V. Bogdanova, Natalia. V. Seredova
Abstract: Effects of electron irradiation in n-4H-SiC have been studied by the methods of the capacitance--voltage characteristics and photoluminescence. It was found that the carrier removal rate (Vd) reached a value of ~0, 25 cm- 1. Full compensation of samples with an initial concentration of 1.2 1015 cm -3 was observed at doses of about 5 1015 cm -2. Simultaneously with the increase in the degree of compensation, the intensity of the “defect luminescence”, typical of 4H SiC, became higher. The physical compensation mechanisms were analyzed for the samples under study.
Authors: Alexander A. Lebedev, D.V. Davydov, Anatoly M. Strel'chuk, Alexey N. Kuznetsov, Elena V. Bogdanova, Vitalii V. Kozlovski, N.S. Savkina
Authors: Alexander A. Lebedev, Klavdia S. Davydovskaya, Vitalii V. Kozlovski, Oleg Korolkov, Natalja Sleptsuk, Jana Toompuu
Abstract: In this paper investigation of degradation 4H SiC Schottky diodes parameters after irradiation by electrons with an energy of 0.9 MeV was doine. It was determined the carrier removal rate (Vd), which amounted to 0.07 - 0.09 cm-1. It is shown that the investigated Schottky diodes retained rectifying current-voltage characteristics of up to doses ~ 1017 cm-2. It is concluded that the radiation resistance of SiC Schottky diodes is much greater than the radiation resistance of Si p-i-n diodes with the same breakdown voltages
Authors: Vitalii V. Kozlovski, Elena V. Bogdanova, Valentin V. Emtsev, Konstantin V. Emtsev, Alexander A. Lebedev, V.N. Lomasov
Abstract: A comparison study of radiation damage in n-type silicon grown by the floating zone technique and n-type silicon carbide grown by the sublimation epitaxy technique was carried out for the first time under the same irradiation conditions. This comparison is drawn for an energy region of fast electrons at ≈ 1 MeV where Frenkel pairs as primary defects, i e the self-interstials bound to their parent vacant sites at a distance of a few lattice spacings, are produced most effectively. The removal rates of charge carriers in n-Si and n-SiC (4H and 6H) were found to be about 0.23 cm-1 and 0.015 cm-1, respectively. The possible reasons of the observed difference are briefly discussed.
Authors: Alexander A. Lebedev, Boris Ya. Ber, Gagik A. Oganesyan, Sergey V. Belov, Natalia. V. Seredova, Irina P. Nikitina, Sergey P. Lebedev, Lev V. Shakhov, Vitalii V. Kozlovski
Abstract: Effects of proton irradiation in n-3C-SiC grown by sublimation on a 4H-SiC substrate have been studied by the Hall effect and photoluminescence methods. It was found that the carrier removal rate (Vd) reaches a value of ~110 cm-1. The full compensation of samples with an initial concentration of (1-2) x 1018 cm -3 was estimated to occur at doses of about 6 x 1015 cm -2. Compared with 4H and 6H silicon carbide, no significant increase in the intensity of so-called "defective" photoluminescence was observed in 3C-SiC.
Authors: Anatoly M. Strel'chuk, Anton E. Kalyadin, Alexander A. Lebedev, Vitalii V. Kozlovski, Leonid P. Romanov, Victor A. Petrov
Abstract: A study of how electron irradiation affects the current-voltage (I-V) and electroluminescence (EL) characteristics of two types of 4H-SiC n+p structures with p-base and base doping to ~5∙1015 cm-3 is presented. The characteristics were measured prior to irradiation and after each of five stages of irradiation with 0.9 MeV electrons at doses in the range from 1∙1015 to 1.1∙1016 cm-2. The irradiation leads to an increase in the recombination current, decrease in the intensity of the edge EL (hνmax≈3.18 eV), and increase in the intensity of the infra-red (IR) EL (hνmax≈1.35 eV), which starts to predominate. Presumably, this indicates that the nonequilibrium carrier lifetime decreases and the concentration of acceptor type defects grows as a result of the irradiation. The IR EL, attributed to a complex defect containing a silicon vacancy, is of interest for development of single-photon sources of light.
Authors: Alexander A. Lebedev, Vitalii V. Kozlovski, Michael E. Levinshtein, S.L. Rumyantsev, John W. Palmour
Abstract: Electron irradiation of high voltage Ni/4H-SiC Schottky diodes with the dose Φ=(0.2-7)×1016cm-2 led to increase in the base resistance, appearance of slow relaxation processes at extremely small currents, and increase of the low frequency noise. On exponential part of the current-voltage characteristics and on linear part of current-voltage characteristics in non-irradiated samples, low frequency noise always has the form of the 1/f noise. On linear part of the current-voltage characteristics in irradiated diodes the generation recombination (GR) noise predominates. Temperature dependences of the base resistivity and character of GR noise indicate that mainly Z1/2 center contributes to the change in the parameters of irradiated samples. Capture cross section of this level, obtained from noise measurements, is within the range (8×10-16-2×10-15) cm2 and only weakly depends on temperature.
Authors: Vadim V. Emtsev, Nikolay V. Abrosimov, Vitalii V. Kozlovski, Gagik A. Oganesyan
Abstract: Electrical properties of radiation-produced defects in p-Ge irradiated with MeV electrons and protons are investigated. The dominant defects in electron-irradiated p-Ge were found to be neutral for the most part, whereas they are electrically active in proton-irradiated materials. Evidently, the reactions between impurity atoms and intrinsic point defects leading to formation of secondary Ga-related defects in electron-and proton-irradiated p-Ge appear to be distinct. Production rates of radiation defects in n-Ge and p-Ge are compared. A marked difference in the removal rates of shallow donor/acceptor impurity states, at least by an order-of-magnitude, is thought to be due to greatly enhanced annihilation of Frenkel pairs in p-type Ge.
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