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

Abstract

Solar-blind photoresistors based on Mg0.48Zn0.52O 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 Mg0.48Zn0.52O thin films are demonstrated by X-ray diffraction and absorption spectra. The MgZnO photoresistors exhibit a large dark/photoresistance ratio up to 1.7 × 104 with the light intensity of 0.61 mW/cm2 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.