Hydrogen as a probe of V_Ga(2) in β-Ga₂O₃

While a number of O-H and O-D lines have been observed for hydrogen and deuterium in β-Ga₂O₃, it has been commonly reported that there is no absorption for the polarization E//[010] [1,2]. This experimental result has led to O-H and O-D defect structures that involve shifted configurations of a vancancy at the tetrahedrally coordinated Ga(1) site and have ruled out structures that involve a vacancy at the octahedrally coordinated Ga(2) site because these structures are predicted to show absorption for E//[010] [1,2]. Weak O-D lines at 2475 and 2493 cm^-1 with components of their polarization with E//[010] have been discovered for β-Ga₂O₃ annealed in a D₂ ambient and are discussed here. O-D defect structures involving a V_Ga(2) are proposed for these centers and an estimate is made for a lower limit of the concentration of V_Ga(2) in the samples from the intensities of the IR absorption lines.

[1] P. Weiser et al., Appl. Phys. Lett. 112, 232104 (2018).

[2] Y. Qin et al., ECS J. Solid State Sci. Technol. 8, Q3103 (2019).