Conducting surface layers formed by hydrogenation of O-implanted β-Ga2O3

Lightly n-type β-Ga2O3 grown by Halide Vapor Phase Epitaxy (HVPE) on heavily n-type doped β-Ga2O3 substrate was implanted with 1 MeV O ions to a fluence of 1016 cm−2. The film remained β-polymorph and showed no broadening of the x-ray rocking curve width after irradiation even though the calculated number of primary defects was very high. The implanted region was characterized by a strong compensation, likely due to the presence of a high density of split Ga vacancy acceptors. Treatment of the irradiated film in dense hydrogen plasma at 330 °C for 0.5 h led to the formation of a conducting surface layer about 0.5 µm-thick with carrier density 1017 cm−3, a suppression of the signal due to Fe acceptors in Deep Level transient Spectroscopy (DLTS) and a strong enhancement of DLTS peak caused by centers at Ec-0.74 eV (so called E2 * traps). The mechanism appears to be that hydrogen plasma treatment leads to creation of a high number of donor states due complexing of hydrogen with Ga vacancies and to passivation of Fe acceptors with hydrogen donors.