Fibrous Al-Doped ZnO Thin Film Ultraviolet Photodetectors With Improved Responsivity and Speed

Ultraviolet (UV) detection properties of undoped ZnO and Al-doped ZnO (AZO) based interdigitated metal-semiconductor-metal (MSM) structure are investigated in this paper. High quality of fibrous Al-doped ZnO thin films with enhanced conductivity and optical response with controlled doping of Al are synthesized using low-cost sol-gel method. The surface morphology and absorption properties of the films have been investigated. The responsivity and detectivity characteristics of both the devices are compared over 300-700 nm wavelengths. The Al-doped ZnO based Ag/AZO/Ag MSM structure show the maximum responsivity and detectivity of ~5.63 A/W and ~1.8 × 10
¹²
cmHz
^1/2
W
^-1
while the respective values for the Ag/undoped-ZnO/Ag photodetector are ~3.65 A/W and ~1.3 × 10
¹²
cmHz
^1/2
W
^-1
at 365 nm and 34 μW/cm
²
incident UV intensity. The proposed AZO based MSM photodetector has smaller rise time (~30 s) than that (~35 s) of the undoped ZnO based MSM photodetector. However, the AZO based device shows slightly poor spectrum selectivity over the undoped ZnO based device.