Gallium-oxide films obtained by thermal evaporation

The current-voltage (I–V), capacitance-voltage ($C$–$V$), and conductance-voltage ($G$–$V$) characteristics of metal/Ga$_x$O$_y$/GaAs/metal structures are investigated. Gallium-oxide films with a thickness of 150–170 nm are deposited by the thermal evaporation of Ga$_2$O$_3$ powder onto $n$-type GaAs substrates with the donor concentration $N_d$ = 2 $\times$ 10$^{16}$ cm$^{-3}$. Treatment of the Ga$_x$O$_y$ films in oxygen plasma causes a decrease in both the forward and reverse currents and a shift of the $C$–$V$ and $G$–$V$ curves to higher positive voltages. The Fermi level at the insulator/semiconductor interface in the structures under study is unpinned. The density of states at the Ga$_x$O$_y$ /GaAs interface is $N_t$ = (2–6) $\times$ 10$^{12}$ eV$^{-1}$cm$^{-2}$.