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

Journal Article · Sun Dec 28 00:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4904927· OSTI ID:22399165

Golden, E. M.; Giles, N. C. ^[1]; Basun, S. A. ^[2]; Grabar, A. A.; Stoika, I. M. ^[3]; Evans, D. R. ^[2]; Halliburton, L. E. ^[4]

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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. Institute of Solid State Physics and Chemistry, Uzhgorod National University, 88 000 Uzhgorod (Ukraine)
4. Azimuth Corporation, 4134 Linden Avenue, Suite 300, Dayton, Ohio 45431 (United States)

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. Before 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.

• OSTI ID: 22399165
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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