Fabrication of ultraviolet detector based on ZnO thin films

Abstract

 metal-semiconductor-metal photoconductive ultraviolet detector was fabricated based on ZnO thin films by RF technique. Results for current versus voltage were measured using semiconductor characterization system in darkness and under illumination of 380 nm UV light at room temperature and in the air ambient. I-V measurements showed a noticeable difference between photocurrent and dark current meaning that the device can be used as UV photodetector. The device showed photocurrent values of 8.84×10^-6,2.07×10^-5, 3.69×10^-5, 6.18×10^-5,7.81×10^-5,1.01×10^-4and 1.23×10^-4 A for the voltages values of 2, 3,4, 5,6, 7 and 8 V, respectively. The responsivity of the fabricated device increased linearly from 0.18 to 2.46 A/W as the bias voltage increased from 2 to 8 V. As the device was supplied with a higher bias voltage, the depletion layer width at the grain boundaries decreased and the carrier concentration increased leading to a larger photocurrent value in the device when it was illuminated with UV light.