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arXiv · 2201.01861

Persistent room temperature photodarkening in Cu-doped \b{eta}-Ga2O3

J. Jesenovec·C. Pansegrau·M. D. McCluskey·J. S. McCloy·T. D. Gustafson·L. E. Halliburton·J. B. Varley
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Abstract

Beta-Ga2O3 is an ultra-wide bandgap semiconductor with emerging applications in power electronics. The introduction of acceptor dopants yields semi-insulating substrates necessary for thin-film devices. In the present work, exposure of Cu-doped Ga2O3 to UV light > 4 eV is shown to cause large, persistent photo-induced darkening at room temperature. Electron paramagnetic resonance spectroscopy indicates that light exposure converts Cu2+ to Cu3+, a rare oxidation state that is responsible for the optical absorption. The photodarkening is accompanied by the appearance of O-H vibrational modes in the infrared spectrum. Hybrid function calculations show that Cu acceptors can favorably complex with hydrogen donors incorporated as interstitial (Hi) or substitutional (H_O) defects. When Cu_Ga-H_O complexes absorb light, hydrogen is released, contributing to the observed Cu3+ species and O-H modes.

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J. Jesenovec, C. Pansegrau, M. D. McCluskey, J. S. McCloy, T. D. Gustafson, L. E. Halliburton, J. B. Varley. 2022-01-05. Persistent room temperature photodarkening in Cu-doped \b{eta}-Ga2O3. https://doi.org/10.1103/physrevlett.128.077402

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