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Title: Effect of the energy of bombarding electrons on the conductivity of n-4H-SiC (CVD) epitaxial layers

Abstract

The electrical characteristics of epitaxial layers of n-4H-SiC (CVD) irradiated with 0.9 and 3.5MeV electrons are studied. It is shown that the donor removal rate becomes nearly four times higher as the energy of impinging electrons increases by a factor of 4, although the formation cross section of primary radiation defects (Frenkel pairs in the carbon sublattice) responsible for conductivity compensation of the material is almost energy independent in this range. It is assumed that the reason for the observed differences is the influence exerted by primary knocked-out atoms. First, cascade processes start to manifest themselves with increasing energy of primary knocked-out atoms. Second, the average distance between genetically related Frenkel pairs grows, and, as a consequence, the fraction of defects that do not recombine under irradiation becomes larger. The recombination radius of Frenkel pairs in the carbon sublattice is estimated and the possible charge state of the recombining components is assessed.

Authors:
 [1]; ; ;  [2];  [1];  [3]
  1. Peter the Great St. Petersburg State Polytechnic University (Russian Federation)
  2. Ioffe Physical–Technical Institute (Russian Federation)
  3. Belarusian State University (Belarus)
Publication Date:
OSTI Identifier:
22649613
Resource Type:
Journal Article
Resource Relation:
Journal Name: Semiconductors; Journal Volume: 51; Journal Issue: 3; Other Information: Copyright (c) 2017 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBON; CHARGE STATES; CHEMICAL VAPOR DEPOSITION; CROSS SECTIONS; CRYSTAL LATTICES; ELECTRIC CONDUCTIVITY; ELECTRONS; ENERGY DEPENDENCE; EPITAXY; IRRADIATION; LAYERS; N-TYPE CONDUCTORS; PHYSICAL RADIATION EFFECTS; POINT DEFECTS; RECOMBINATION; SILICON CARBIDES

Citation Formats

Kozlovski, V. V., E-mail: kozlovski@physics.spbstu.ru, Lebedev, A. A., Strel’chuk, A. M., Davidovskaya, K. S., Vasil’ev, A. E., and Makarenko, L. F. Effect of the energy of bombarding electrons on the conductivity of n-4H-SiC (CVD) epitaxial layers. United States: N. p., 2017. Web. doi:10.1134/S1063782617030137.
Kozlovski, V. V., E-mail: kozlovski@physics.spbstu.ru, Lebedev, A. A., Strel’chuk, A. M., Davidovskaya, K. S., Vasil’ev, A. E., & Makarenko, L. F. Effect of the energy of bombarding electrons on the conductivity of n-4H-SiC (CVD) epitaxial layers. United States. doi:10.1134/S1063782617030137.
Kozlovski, V. V., E-mail: kozlovski@physics.spbstu.ru, Lebedev, A. A., Strel’chuk, A. M., Davidovskaya, K. S., Vasil’ev, A. E., and Makarenko, L. F. Wed . "Effect of the energy of bombarding electrons on the conductivity of n-4H-SiC (CVD) epitaxial layers". United States. doi:10.1134/S1063782617030137.
@article{osti_22649613,
title = {Effect of the energy of bombarding electrons on the conductivity of n-4H-SiC (CVD) epitaxial layers},
author = {Kozlovski, V. V., E-mail: kozlovski@physics.spbstu.ru and Lebedev, A. A. and Strel’chuk, A. M. and Davidovskaya, K. S. and Vasil’ev, A. E. and Makarenko, L. F.},
abstractNote = {The electrical characteristics of epitaxial layers of n-4H-SiC (CVD) irradiated with 0.9 and 3.5MeV electrons are studied. It is shown that the donor removal rate becomes nearly four times higher as the energy of impinging electrons increases by a factor of 4, although the formation cross section of primary radiation defects (Frenkel pairs in the carbon sublattice) responsible for conductivity compensation of the material is almost energy independent in this range. It is assumed that the reason for the observed differences is the influence exerted by primary knocked-out atoms. First, cascade processes start to manifest themselves with increasing energy of primary knocked-out atoms. Second, the average distance between genetically related Frenkel pairs grows, and, as a consequence, the fraction of defects that do not recombine under irradiation becomes larger. The recombination radius of Frenkel pairs in the carbon sublattice is estimated and the possible charge state of the recombining components is assessed.},
doi = {10.1134/S1063782617030137},
journal = {Semiconductors},
number = 3,
volume = 51,
place = {United States},
year = {Wed Mar 15 00:00:00 EDT 2017},
month = {Wed Mar 15 00:00:00 EDT 2017}
}
  • The compensation of moderately doped p-4H-SiC samples grown by the chemical vapor deposition (CVD) method under irradiation with 0.9-MeV electrons and 15-MeV protons is studied. The experimentally measured carrier removal rates are 1.2–1.6 cm{sup –1} for electrons and 240–260 cm{sup –1} for protons. The dependence of the concentration of uncompensated acceptors and donors, measured in the study, demonstrates a linear decrease with increasing irradiation dose to the point of complete compensation. This run of the dependence shows that compensation of the samples is due to the transition of carriers to deep centers formed by primary radiation-induced defects. It is demonstratedmore » that, in contrast to n-SiC (CVD), primary defects in the carbon sublattice of moderately doped p-SiC (CVD) only cannot account for the compensation process. In p-SiC, either primary defects in the silicon sublattice, or defects in both sublattices are responsible for conductivity compensation. Also, photoluminescence spectra are examined in relation to the irradiation dose.« less
  • Spectroscopic performance of Schottky barrier alpha particle detectors fabricated on 50 μm thick n-type 4H-SiC epitaxial layers containing Z{sub 1/2}, EH{sub 5}, and Ci1 deep levels were investigated. The device performance was evaluated on the basis of junction current/capacitance characterization and alpha pulse-height spectroscopy. Capacitance mode deep level transient spectroscopy revealed the presence of the above-mentioned deep levels along with two shallow level defects related to titanium impurities (Ti(h) and Ti(c)) and an unidentified deep electron trap located at 2.4 eV below the conduction band minimum, which is being reported for the first time. The concentration of the lifetime killer Z{sub 1/2}more » defects was found to be 1.7 × 10{sup 13} cm{sup −3}. The charge transport and collection efficiency results obtained from the alpha particle pulse-height spectroscopy were interpreted using a drift-diffusion charge transport model. Based on these investigations, the physics behind the correlation of the detector properties viz., energy resolution and charge collection efficiency, the junction properties like uniformity in barrier-height, leakage current, and effective doping concentration, and the presence of defects has been discussed in details. The studies also revealed that the dominating contribution to the charge collection efficiency was due to the diffusion of charge carriers generated in the neutral region of the detector. The 10 mm{sup 2} large area detectors demonstrated an impressive energy resolution of 1.8% for 5486 keV alpha particles at an optimized operating reverse bias of 130 V.« less
  • Schottky diodes on n-type 4H-SiC epitaxial layers have been fabricated for low-energy x-ray detection. The detectors were highly sensitive to soft x-rays and showed improved response compared to the commercial SiC UV photodiodes. Current-voltage characteristics at 475 K showed low leakage current revealing the possibility of high temperature operation. The high quality of the epi-layer was confirmed by x-ray diffraction and chemical etching. Thermally stimulated current measurements performed at 94-550 K revealed low density of deep levels which may cause charge trapping. No charge trapping on detectors' responsivity in the low x-ray energy was found.
  • It is shown that 9-μm-thick semi-insulating surface layers can be formed in moderately doped n-type silicon carbide (donor concentration 2 × 10{sup 16} cm{sup –3}) via the comparatively low-dose (7 × 10{sup 11} cm{sup –2}) implantation of high-energy (53 MeV) argon ions. The free-carrier removal rate is estimated at ~10{sup 4} cm{sup –1}. The resistivity of the semi-insulator is no less than 7 × 10{sup 12} Ω cm. Analysis of the monopolar current of electron injection into the semi-insulator shows that the impurity-conductivity compensation is due to radiation induced defects pinning the equilibrium Fermi level at a depth of 1.16more » eV below the conduction-band bottom. The density of defect states at the Fermi level is 2.7 × 10{sup 16} cm{sup 2} eV{sup –1}.« less