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Hole trapping facilitates the formation of Frenkel pairs in crystalline and amorphous Ga2O3 films

Chaiyawat Kaewmeechai1,*, Jack Strand1,2, and Alexander Shluger1,3

  • 1Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
  • 2Nanolayers Research Computing Ltd., London NW9 6PL, United Kingdom
  • 3WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2–1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

  • *Contact author: chaiyawat.kaewmeechai.20@ucl.ac.uk
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Phys. Rev. B 112, 205203 – Published 7 November, 2025

DOI: https://doi.org/10.1103/jmq5-9yy9

Abstract

Holes are injected from electrodes or produced by irradiation in many applications of crystalline and amorphous Ga2O3. They are known to trap in polaron states in both phases. We investigate, using density functional theory, how hole trapping in Ga2O3 can lead to creation of Frenkel pairs (FPs) of oxygen vacancies in the +2 charge state, VO2+, and interstitial oxygen atoms. The calculations reveal that hole bipolarons lead to the formation of O–O dimers, distorting adjacent Ga–O bonds and resulting in a significant reduction of the barriers for the nearest-neighbor FP formation with respect to pristine structures. In amorphous Ga2O3 the barriers are on average 2.05 eV, much lower than in the crystalline phase, where they are 3.47 to 4.80 eV. Furthermore, in the amorphous phase, the migration barriers for oxygen vacancies in the +2 charge state, VO2+, are reduced compared to those in the crystalline phase, indicating that VO2+ can drift away under the influence of electric fields, creating stable defects. These results show that hole trapping in Ga2O3 can facilitate the formation of FPs, particularly in amorphous structures. They can be useful in understanding the mechanisms of degradation in Ga2O3 based devices under negative bias and illumination stress.

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Phys. Rev. B 112, 205203– Published 7 November, 2025
  • Received 4 June 2025
  • Revised 21 August 2025
  • Accepted 17 October 2025
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