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Title: Sulfur vacancies in photorefractive Sn{sub 2}P{sub 2}S{sub 6} crystals

A photoinduced electron paramagnetic resonance (EPR) spectrum in single crystals of Sn{sub 2}P{sub 2}S{sub 6} (SPS) is assigned to an electron trapped at a sulfur vacancy. These vacancies are unintentionally present in undoped SPS crystals and are expected to play an important role in the photorefractive behavior of the material. Nonparamagnetic sulfur vacancies are formed during the initial growth of the crystal. Subsequent illumination below 100 K with 442 nm laser light easily converts these vacancies to EPR-active defects. The resulting S = 1/2 spectrum shows well-resolved and nearly isotropic hyperfine interactions with two P ions and two Sn ions. Partially resolved interactions with four additional neighboring Sn ions are also observed. Principal values of the g matrix are 1.9700, 1.8946, and 1.9006, with the corresponding principal axes along the a, b, and c directions in the crystal. The isotropic parts of the two primary {sup 31}P hyperfine interactions are 19.5 and 32.6 MHz and the isotropic parts of the two primary Sn hyperfine interactions are 860 and 1320 MHz (the latter values are each an average for {sup 117}Sn and {sup 119}Sn). These hyperfine results suggest that singly ionized sulfur vacancies have a diffuse wave function in SPS crystals, and thus are shallow donors. Beforemore » illumination, sulfur vacancies are in the doubly ionized charge state because of compensation by unidentified acceptors. They then trap an electron during illumination. The EPR spectrum from the sulfur vacancy is destroyed when a crystal is heated above 120 K in the dark and reappears when the crystal is illuminated again at low temperature.« less
Authors:
;  [1] ;  [2] ;  [3] ; ;  [4] ;  [2] ;  [5] ;  [3]
  1. Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio 45433 (United States)
  2. Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433 (United States)
  3. (United States)
  4. Institute of Solid State Physics and Chemistry, Uzhgorod National University, 88 000 Uzhgorod (Ukraine)
  5. Azimuth Corporation, 4134 Linden Avenue, Suite 300, Dayton, Ohio 45431 (United States)
Publication Date:
OSTI Identifier:
22399165
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION SPECTRA; CHARGE STATES; ELECTRON SPIN RESONANCE; ELECTRONS; G MATRIX; HYPERFINE STRUCTURE; MHZ RANGE; MONOCRYSTALS; PHOSPHORUS 31; PHOSPHORUS IONS; SULFUR; TIN 117; TIN 119; TIN IONS; TIN PHOSPHIDES; TIN SULFIDES; TRAPPING; VACANCIES; WAVE FUNCTIONS