Acceptors in gallium oxide

Monoclinic gallium oxide (β-Ga₂O₃) is an ultra-wide bandgap semiconductor with potential applications in power electronics. Semi-insulating substrates are required for most practical devices such as metal-oxide-semiconductor field effect transistors. This presentation will discuss recent experimental studies on Czochralski-grown β-Ga₂O₃ single crystals doped with Mg and Zn acceptors. These dopants result in semi-insulating material and are likely compensated by oxygen vacancies and shallow donors. Ir impurities originating from the crucible form deep donors that also compensate acceptors. The Ir⁴⁺ oxidation state gives rise to an absorption threshold in the visible/UV part of the spectrum and an IR absorption peak at 5150 cm^-1. Acceptors are passivated by hydrogen, an omnipresent contaminant, resulting in IR absorption peaks corresponding to O-H vibrational modes near 3300 cm^-1.