1. Deep selenium donors in ZnGeP2 crystals: An electron paramagnetic resonance study of a nonlinear optical material.
- Author
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Gustafson, T. D., Halliburton, L. E., Giles, N. C., Schunemann, P. G., Zawilski, K. T., Jesenovec, J., Averett, K. L., and Slagle, J. E.
- Subjects
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ELECTRON paramagnetic resonance , *NONLINEAR optical materials , *SELENIUM , *OPTICAL parametric oscillators , *DISTRIBUTION (Probability theory) , *CRYSTALS , *ELECTRON paramagnetic resonance spectroscopy - Abstract
Zinc germanium diphosphide (ZnGeP2) is a ternary semiconductor best known for its nonlinear optical properties. A primary application is optical parametric oscillators operating in the mid-infrared region. Controlled donor doping provides a method to minimize the acceptor-related absorption bands that limit the output power of these devices. In the present study, a ZnGeP2 crystal is doped with selenium during growth. Selenium substitutes for phosphorus and serves as a deep donor. Significant concentrations of native defects (zinc vacancies, germanium-on-zinc antisites, and phosphorous vacancies) are also present in the crystal. Electron paramagnetic resonance (EPR) is used to establish the atomic-level model for the neutral charge state of the selenium donor. The S = 1/2 signal from the neutral donors is produced at 6 K by illuminating with 633 nm light (electrons excited from doubly ionized Zn vacancies convert Se P + donors to Se P 0 donors). A g matrix, with principal values of 2.088, 2.203, and 1.904, is extracted from the angular dependence of the EPR spectrum. The principal-axis direction associated with the 1.904 principal value is close to a Se–Ge bond. This indicates an asymmetric distribution of unpaired spin density around the selenium ion and thus predicts the deep donor behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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