The Effects of Mg Contents on MgxZn1−xO-Based Metal-Semiconductor-Metal Ultraviolet Photodetectors by Ultrasonic Spray Pyrolysis Deposition

The Mg
_x
Zn
_1-x
O thin films with Mg/Zn mole fraction of 0.1/0.9, 0.2/0.8, and 0.3/0.7 were deposited by the ultrasonic spray pyrolysis deposition method. The X-ray diffraction, X-ray photoelectron spectroscopy, and Raman were used to analyze the material characteristics, including crystal structures, crystal orientations, chemical qualitative, and quantitative characteristics. The photoluminescence spectrum was used to observe the near-band-edge emission and trap energy level. The refractive index and extinction coefficient of the Mg
_x
Zn
_1-x
O thin films were measured by the ellipsometer. The metal-semiconductor-metal structure photodetectors were fabricated. The electrical characteristics, including current-voltage and Schottky barrier height characteristics were investigated. The photoresponse showed that the Mg
_0.1
Zn
_0.9
O-based photodetector had the highest photoresponsivity and the Mg
_0.3
Zn
_0.7
O-based photodetector had the shortest response time and the highest detectivity. Further, the contents of Mg in the Mg
_x
Zn
_1-x
O affected the cutoff wavelength of the photodetector.