The effect of annealing on the properties of Ga$_2$O$_3$ anodic films

The effect of annealing and oxygen plasma on the electrical characteristics of gallium oxide films has been investigated. Ga$_2$O$_3$ films with thicknesses of 200–300 nm were formed by the anodic oxidation of $n$-GaAs wafers with the donor concentration $N_d$ = (1–2) $\times$ 10$^{16}$ cm$^{-3}$. It is shown that, after annealing at 900$^\circ$C for 30 min, the gallium arsenide films contain only the $\beta$ Ga$_2$O$_3$ phase. The effect of the duration of oxygen plasma treatment prior to annealing on the nucleation of $\beta$-phase crystallites with different orientations has been studied. It has been established that the electrical conductivity of the Ga$_2$O$_3$ films can be managed by annealing and variation in the duration of oxygen plasma treatment. It is shown that the response of the V/Ni–GaAs–Ga$_2$O$_3$–V/Ni structure to a mixture exhaled by a person depends on the value and sign of the potential on the control electrode.