High Responsivity Mg x Zn 1– x O Based Ultraviolet Photodetector Fabricated by Dual Ion Beam Sputtering

Mg x Zn 1– x O ( $x = 0.05$ , 0.15 and 0.20) based metal–semiconductor–metal ultraviolet (UV) photodetectors were fabricated on Si substrate using dual-ion-beam sputtering. The performances of fabricated photodetectors were studied by current–voltage, spectral photoresponse, and temporal response measurements. The values of peak responsivity of photodetectors were 0.4, 0.31, and 0.27 A/W with corresponding external quantum efficiency of 146%, 110%, and 105% for $x = 0.05$ , 0.15 and 0.20, respectively. The cutoff wavelength and UV/visible rejection ratio of fabricated photodetectors decrease over 360–330 nm and 341.8–115.3, respectively, with increase in Mg concentration. The variation in specific detectivity and noise equivalent power with Mg concentration variation is also reported.