Multiple O-H centers in β-Ga₂O₃

Hydrogen impurities play a crucial role in the electrical conductivity of β-Ga₂O₃ by acting as shallow donors and by passivating deep acceptors [1,2]. Polarized IR spectroscopy in conjunction with heat treatments of β-Ga₂O₃ single crystals treated in an H₂ (D₂) ambient reveals a number of vibrational lines originating from defects containing one or more O-H(D) species[3,4]. Theoretical calculations using the CRYSTAL06 code [5] with hybridized DFT Hamiltonian and the polarization properties of these vibrational lines are used to suggest structures involving one, two, or three O-H(D) species for these defects. We find strong evidence for one or more O-H(D) associated with Ga(1) vacancies and no evidence for any O-H(D) associated with Ga(2) vacancies in the crystals studied.
[1] J. B. Varley et al., Appl. Phys. Lett. 97, 142016 (2010).
[2] J. B. Varley et al., J. Phys.: Condens. Matter 23 (2011), 334212.
[3] P. Weiser et al., Appl. Phys. Lett. 112, 232104 (2018).
[4] M. Stavola et al., Vibrational spectroscopy of O-H Centers in Ga₂O₃, this session.
[5] R. Dovesi et al., Crystal06 User’s Manual (University of Torino, Torino, 2006).