Simulation, Fabrication, and Characterization of Al-Doped ZnO-Based Ultraviolet Photodetectors

This paper reports a simulation and experimental study of aluminum-doped zinc oxide (AZO)-based metal-semiconductor-metal (MSM) photodetectors. High-quality AZO thin films were deposited on p-type Si substrates by radiofrequency (RF) sputtering method. Interdigitated palladium metal electrodes were designed over AZO/Si samples by lithographic technique. I-V detector characteristics were investigated in dark as well as illuminated condition, using an ultraviolet (UV) source with wavelength of 0.372 mu m and power of 2.8 x 10(-6) W. Four different MSM devices with the same width and finger spacing of 5 mu m, 10 mu m, 20 mu m, and 50 mu m were fabricated, and the effect of finger spacing on the MSM detector I-V characteristics was investigated. It was found that the photocurrent increased by more than two orders of magnitude with UV light illumination. Simulation of these MSM devices was also carried out by using SENTAURUS TCAD software. The variation of the resistance with the electrode spacing for the MSM devices was examined by both experiment and simulation. The simulated and experimental results were compared and found to be in good agreement with each other. In both conditions (dark as well as under UV illumination), the resistance increased as the spacing between the electrodes was increased. These simulation studies will be useful for designing high-performance optoelectronic devices.