Schottky Barrier Photodetectors Based on Mg0.40Zn0.60O Thin Films

Wurtzite (Mg0.40Zn0.60O) thin films have been grown on quartz substrates by using the radio frequency magnetron sputtering technique, and a metal−semiconductor−metal Schottky barrier photodetector has been fabricated from these films. The photodetector exhibits a peak responsivity at 276 nm and a very sharp cutoff wavelength at 295 nm corresponding to the absorption edge of the Mg0.40Zn0.60O thin film. At 2 V bias, the detectivity of the photodetector is 1.1 × 1012 (cm Hz1/2)/W at 276 nm, and the ultraviolet-to-visible rejection ratio [R(276 nm)/R(400 nm)] is about 4 orders of magnitude. The photodetector also exhibits a very low dark current of about 100 pA at 2 V bias.