In this study, the optical and electrical properties of a zinc tin oxide (ZTO) thin-film transistor (TFT) were investigated. The TFT was fabricated using ZTO as the active layer, which was deposited by a radio frequency magnetron sputtering system, to form an ultraviolet (UV) photodetector.
The device has a threshold voltage of 0.48 V, field-effect mobility of 1.47 cm2/Vs in the saturation region, on/off drain current ratio of 2×106, and subthreshold swing of 0.45 V/decade in a dark environment. Moreover, as a UV photodetector, the device has a long
photoresponse time, responsivity of 0.329 A/W, and rejection ratio of 3.19×104 at a gate voltage of -15 V under illumination of wavelength 300 nm.
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.
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