The (311) peak in the thin-film curves indicates standard diffraction pattern of ZnGa2O4 while the (220) peak suggests a preferred orientation,
and the intensities of the two large peaks [(311) and (220)] in the thin-film curves are almost equal, which is consistent with the result reported by Park et al. [17]. From the comparison of the two thin film samples, we see that the sample deposited at an oxygen pressure of 1 Pa (the 1-Pa film sample) exhibits diffraction peaks with stronger intensity and narrower full-width at half-maximum value.