Ir4+ Ions in β-Ga2O3 Crystals: An Unintentional Deep Donor
Document Type
Article
Publication Date
1-2019
Abstract
Electron paramagnetic resonance (EPR) and infrared absorption are used to detect Ir4+ ions in β-Ga2O3 crystals. Mg and Fe doped crystals are investigated, and concentrations of Ir4+ ions greater than 1 × 1018 cm−3 are observed. The source of the unintentional deep iridium donors is the crucible used to grow the crystal. In the Mg-doped crystals, the Ir4+ ions provide compensation for the singly ionized Mg acceptors and thus contribute to the difficulties in producing p-type behavior. The Ir4+ ions replace Ga3+ ions at the Ga(2) sites, with the six oxygen neighbors forming a distorted octahedron. A large spin-orbit coupling causes these Ir4+ ions to have a low-spin (5d5, S = 1/2) ground state. The EPR spectrum consists of one broad line with a significant angular dependence. Principal values of the g matrix are 2.662, 1.815, and 0.541 (with principal axes near the crystal a, b, and c directions, respectively). Ionizing radiation at 77 K decreases the Ir4+ EPR signal in Mg-doped crystals and increases the signal in Fe-doped crystals. In addition to the EPR spectrum, the Ir4+ ions have an infrared absorption band representing a d-d transition within the t2g orbitals. At room temperature, this band peaks near 5153 cm−1 (1.94 μm) and has a width of 17 cm−1. The band is highly polarized: its intensity is maximum when the electric field E is parallel to the b direction in the crystal and is nearly zero when E is along the c direction.
Source Publication
Journal of Applied Physics (ISSN 0021-8979 | e-ISSN 1089-7550)
Recommended Citation
Lenyk, C. A., Giles, N. C., Scherrer, E. M., Kananen, B. E., Halliburton, L. E., Stevens, K. T., Foundos, G. K., Blevins, J. D., Dorsey, D. L., & Mou, S. (2019). Ir 4+ ions in β-Ga 2 O 3 crystals: An unintentional deep donor. Journal of Applied Physics, 125(4), 045703. https://doi.org/10.1063/1.5081825
Comments
© 2019 Author(s), published under an exclusive license with American Institute of Physics.
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Funding note: The present work was supported in part by the Air Force Office of Scientific Research under Award Nos. F4FGA08054J003 and FA9550-18RYCOR098
[*] Author note: Christopher Lenyk and Elizabeth Scherrer were AFIT PhD candidates at the time of publication.