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Electron paramagnetic resonance (EPR) is used to experimentally determine the (0/−) level of the Mg acceptor in an Mg-doped β-Ga2O3 crystal. Our results place this level 0.65 eV (±0.05 eV) above the valence band, a position closer to the valence band than the predictions of several recent computational studies. The crystal used in this investigation was grown by the Czochralski method and contains large concentrations of Mg acceptors and Ir donors, as well as a small concentration of Fe ions and an even smaller concentration of Cr ions. Below room temperature, illumination with 325 nm laser light produces the characteristic EPR spectrum from neutral Mg acceptors (Mg0Ga). A portion of the singly ionized Ir4+ donors are converted to their neutral Ir3+ state at the same time. For temperatures near 250 K, the photoinduced EPR spectrum from the neutral Mg0Ga acceptors begins to decay immediately after the laser light is removed, as electrons are thermally excited from the valence band to the Mg acceptor. Holes left in the valence band recombine with electrons at the deeper Ir3+ ions and restore the Ir4+ ions. An activation energy for the thermal decay of the Mg0Ga acceptors, and thus a value for the (0/−) level, is obtained by using a general-order kinetics model to analyze a set of five isothermal decay curves taken at temperatures between 240 and 260 K.


© 2020 Author(s). Published under license by AIP Publishing.

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 Applied Physics Letters, 116: 142101 as fully cited below and may be found at the DOI: 10.1063/5.0002763.

Funding note: "The present work was funded in part by the Air Force Office of Scientific Research under Award No. F4FGA08054J003. One of the authors (T.D.G.) was supported by an NRC Research Associateship Award at the Air Force Institute of Technology."

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Applied Physics Letters