High-Responsivity Solar-Blind Photodetector Based on $\hbox {Mg}_{0.46}\hbox {Zn}_{0.54}\hbox {O}$ Thin Film

Adopting relatively high substrate temperature and low growth rate, single-phase wurtzite Mg_0.46Zn_0.54O film is grown on a quartz substrate by homemade magnetron sputtering. Solar-blind photodetector is fabricated based on the MgZnO film and shows a peak responsivity of 3.4 A/W at 265 nm with a cutoff wavelength of 280 nm under 10 V. As applied voltage increased to 70 V, the peak responsivity is up to 31.1 A/W corresponding to an internal gain of 148 times. The large internal gain was attributed to the trapping of photoionized holes at E_v + 282 meV deep level through deep-level transient spectral measurement.