Document Type
Article
Publication Date
10-2016
Abstract
Electron paramagnetic resonance (EPR) is used to identify the singly ionized charge state of the Sn vacancy (V−Sn) in single crystals of Sn2P2S6 (often referred to as SPS). These vacancies, acting as a hole trap, are expected to be important participants in the photorefractive effect observed in undoped SPS crystals. In as-grown crystals, the Sn vacancies are doubly ionized (V2−Sn) with no unpaired spins. They are then converted to a stable EPR-active state when an electron is removed (i.e., a hole is trapped) during an illumination below 100 K with 633 nm laser light. The resulting EPR spectrum has g-matrix principal values of 2.0079, 2.0231, and 1.9717. There are resolved hyperfine interactions with two P neighbors and one Sn neighbor. The isotropic portions of these hyperfine matrices are 167 and 79 MHz for the two 31P neighbors and 8504 MHz for the one Sn neighbor (this latter value is the average for 117Sn and 119Sn). These V−Sn vacancies are shallow acceptors with the hole occupying a diffuse wave function that overlaps the neighboring Sn2+ ion and (P2S6)4− anionic unit. Using a general-order kinetics approach, an analysis of isothermal decay curves of the V−Sn EPR spectrum in the 107–115 K region gives an activation energy of 283 meV.
Source Publication
Journal of Applied Physics (ISSN 0021-8979)
Recommended Citation
Golden, E. M., Basun, S. A., Evans, D. R., Grabar, A. A., Stoika, I. M., Giles, N. C., & Halliburton, L. E. (2016). Sn vacancies in photorefractive Sn 2 P 2 S 6 crystals: An electron paramagnetic resonance study of an optically active hole trap. Journal of Applied Physics, 120(13), 133101. https://doi.org/10.1063/1.4963825
Comments
© 2016 Author(s), 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.
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 volume 120 of Journal of Applied Physics as cited below and may be found at the DOI link on this page.
Funding notes: The work at the Air Force Institute of Technology was supported by the Air Force Office of Scientific Research (AFOSR Project 16RT0053) and the work at the Uzhgorod National University was supported by the Science and Technology Center in Ukraine and the European Office of Aerospace Research and Development (STCU/EOARD Project P438a).