TiO2-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors Deposited by Ultrasonic Spray Pyrolysis Technique

This paper uses nonvacuum ultrasonic spray pyrolysis deposition method to grow TiO
₂
for ultraviolet (UV) detection. The analyses of the materials like X-ray photoelectron spectroscopy, X-ray diffraction, and photoluminescence were investigated. The 600 °C annealing temperature is the optimum condition to obtain the anatase TiO
₂
. The metal-semiconductor- metal (MSM) photodetectors (PDs) with 3-, 5-, 7-, 10-μm finger spacing were fabricated and the performance was investigated. The PD with 10-μm finger spacing has the lowest dark current of 2.92 × 10
^-11
A and the highest UV-to-visible rejection ratio (RUV/VIS) of 2.1 × 10
⁵
at 5 V. The PD with 5-μm finger spacing has the lowest noise equivalent power of 2.57 × 10
^-9
W and the highest detectivity (D*) of 5.46 × 108 cmHz
^0.5
W
^-1
. The rising time and the falling time of the PD are 5 and 12 s. In addition, the TiO
₂
-based MSM PD in this paper operated normally at 450 K; however, the performance is slightly degraded. The mechanisms causing degradation at high temperature were investigated.