Bandgap Engineered Ultraviolet Photodetectors with Gallium-Zinc-Oxide via Co-Sputtering Method

Abstract

The authors report the fabrication of gallium-zinc-oxide (GZO)MSM ultraviolet photodetectors (PDs) via co-sputtering using Ga 2 O 3 and ZnO targets. The cutoff wavelength of the fabricated PDs is changed by adjusting the radio frequency power of the ZnO target during the co-sputtering procedure. The GZO thin films are investigated via physical analysis, such as atomic force microscopy, absorption coefficient spectroscopy, and X-ray photoelectron spectroscopy. The results indicate that the smooth GZO thin films are composed of a wide-gap semiconductor and a clearly n-type material. With a 10-V applied bias, the corresponding I Photo /I Dark ratios for three devices labeled A, B, and C are 1.4 × 10 3 , 9.3 × 10 2 , and 2.7 × 10 3 , respectively. Under corresponding cutoff wavelengths with a 0.2-V applied bias, the responsivity values are 2.7 × 10 -6 , 9 × 10 -6 , and 1.5 × 10 -4 for devices A, B, and C, respectively. Thus, these GZO ultraviolet PDs not only have a simple and low-cost fabrication process but also are suitable for ultraviolet sensing application owing to their outstanding electro-optical properties.