Document Type
Article
Publication Date
12-29-2014
Abstract
A photoinduced electron paramagnetic resonance (EPR) spectrum in single crystals of Sn2P2S6 (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 31P 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 117Sn and 119Sn). 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.
DOI
10.1063/1.4904927
Source Publication
Journal of Applied Physics
Recommended Citation
Golden, E. M., Basun, S. A., Grabar, A. A., Stoika, I. M., Giles, N. C., Evans, D. R., & Halliburton, L. E. (2014). Sulfur vacancies in photorefractive Sn2P2S6 crystals. Journal of Applied Physics, 116(24), 244107. https://doi.org/10.1063/1.4904927
Included in
Atomic, Molecular and Optical Physics Commons, Semiconductor and Optical Materials Commons
Comments
Copyright: © 2014 AIP Publishing LLC, published under an exclusive license with American Institute of Physics.
AFIT Scholar, as the repository of the Air Force Institute of Technology, furnishes the published Version of Record for this article in accordance with the sharing policy of the publisher, AIP Publishing. A 12-month embargo was observed.
Funding notes: Work at Uzhgorod National University was supported by the European Office of Research and Development (Project P438a).
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics, 116:244107 as fully cited below and may be found at 10.1063/1.4904927.
Plain-text title: Sulfur vacancies in photorefractive Sn2P2S6 crystals.