Document Type

Article

Publication Date

10-2018

Abstract

Lithium gallate (LiGaO2) is a wide-band-gap semiconductor with an optical gap greater than 5.3 eV. When alloyed with ZnO, this material offers broad functionality for optical devices that generate, detect, and process light across much of the ultraviolet spectral region. In the present paper, electron paramagnetic resonance (EPR) is used to identify and characterize neutral lithium vacancies (V0Li) and doubly ionized gallium vacancies (V2−Ga) in LiGaO2 crystals. These S = 1/2 native defects are examples of acceptor-bound small polarons, where the unpaired spin (i.e., the hole) is localized on one oxygen ion adjacent to the vacancy. Singly ionized lithium vacancies (VLi) are present in as-grown crystals and are converted to their paramagnetic state by above-band-gap photons (x rays are used in this study). Because there are very few gallium vacancies in as-grown crystals, a post-growth irradiation with high-energy electrons is used to produce the doubly ionized gallium vacancies (V2−Ga). The EPR spectra allow us to establish detailed models for the two paramagnetic vacancies. Anisotropy in their g matrices is used to identify which of the oxygen ions adjacent to the vacancy has trapped the hole. Both spectra also have resolved structure due to hyperfine interactions with 69Ga and 71Ga nuclei. The V0Li acceptor has nearly equal interactions with Ga nuclei at two Ga sites adjacent to the trapped hole, whereas the V2−Ga acceptor has an interaction with Ga nuclei at only one adjacent Ga site.

Comments

A 12-month embargo was observed before posting, in accordance with AIP policy. Sourced from the version of record as cited below.

© 2018 Authors. 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, 124, 135702 (2018) and may be found at https://doi.org/10.1063/1.5050532.

Plain-text title: Lithium and gallium vacancies in LiGaO2 crystals

DOI

10.1063/1.5050532

Source Publication

Journal of Applied Physics

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