Impact of Hydrogen Plasma on Electrical Properties and Deep Trap Spectra in Ga[sub.2]O[sub.3] Polymorphs

In this study, the results of hydrogen plasma treatments of β-Ga[sub.2]O[sub.3], α-Ga[sub.2]O[sub.3], κ-Ga[sub.2]O[sub.3] and γ-Ga[sub.2]O[sub.3] polymorphs are analyzed. For all polymorphs, the results strongly suggest an interplay between donor-like hydrogen configurations and acceptor complexes formed by hydrogen with gallium vacancies. A strong anisotropy of hydrogen plasma effects in the most thermodynamically stable β-Ga[sub.2]O[sub.3] are explained by its low-symmetry monoclinic crystal structure. For the metastable, α-, κ- and γ-polymorphs, it is shown that the net result of hydrogenation is often a strong increase in the density of centers supplying electrons in the near-surface regions. These centers are responsible for prominent, persistent photocapacitance and photocurrent effects.