Solar-Blind Photoresistors Based on $\hbox{Mg}_{0.48} \hbox{Zn}_{0.52}\hbox{O}$ Thin Films Grown on $r\hbox{-Al}_{2} \hbox{O}_{3}$ Substrates by Radio-Frequency Plasma-Assisted Molecular Beam Epitaxy

Solar-blind photoresistors based on Mg 0.48 Zn 0.52 O thin films were fabricated on r-plane sapphire substrates by radio-frequency plasma-assisted molecular beam epitaxy. High-quality a-plane-orientation single-phase wurtzite Mg 0.48 Zn 0.52 O thin films are demonstrated by X-ray diffraction and absorption spectra. The MgZnO photoresistors exhibit a large dark/photoresistance ratio up to 1.7 × 10 4 with the light intensity of 0.61 mW/cm 2 at 260 nm. The spectral response shows a sharp response peak only in the solar-blind region with maximum responsivity of 1.5 × 10 -3 Ω -1 · W -1 .