Hydrogen Passivation of Calcium and Magnesium Doped β-Ga_2O_3

摘要

Calcium and magnesium doped beta-phase gallium oxide (β-Ga_2O_3) single crystals were Czochralski grown in aniridium crucible and subsequently annealed in hydrogen at ～800℃. IR spectroscopy was used to investigate the roles ofMg and Ca dopants as well as H and Ir impurities. An IR peak at 3492 cm~(-1) was previously assigned to an O-H bondstretchingmode of a MgH complex in hydrogen-annealed Ga_2O_3:Mg and an IR peak at 3541 cm-1 is tentatively assignedto a similar mode in a CaH complex for H annealed Ga_2O_3:Ca. An IR peak at 5148 cm~(-1) is attributed to the presence ofIr~（4+） when magnesium is present. Excitation with several different wavelengths was used to confirm the position of the Irlevel within the band gap. Our results suggest that isolated substitutional Ca dopants are less effective as deep acceptorsthan Mg. Polarization dependence of the iridium IR spectra is also discussed.