Simulation and analysis of Ag/ZnO/AZO/Al photodetector

The introduction of an aluminum-doped zinc oxide (AZO) buffer layer on a glass substrate has been shown to enhance the performance of Ag/ZnO Schottky photodetectors. To further investigate the correlation between the parameters of AZO buffer layer and ZnO active layer and the performance of Ag/ZnO/AZO/Al photodetectors, we constructed an Ag/ZnO/AZO/Al photodetector based on Silvaco TCAD simulation platform to investigate the effects of AZO layer thickness, ZnO layer thickness, AZO doping concentration, and ZnO doping concentration on the device performance. The simulation results demonstrate that the device achieves better performance when the AZO layer thickness ranges from 0.8 μm to 1.2 μm and the ZnO layer thickness ranges from 0.5 μm to 0.8 μm, with an AZO doping concentration of 1×10¹⁹ cm^-3 and a ZnO doping concentration of 1×10¹⁶ cm^-3. Increasing the doping concentration of the AZO buffer layer can enhance the electric field intensity at ZnO-AZO interface, effectively preventing photogenerated holes from approaching ZnO-AZO interface so as to reduce interface recombination; while appropriate ZnO layer thickness and doping concentration can optimize the space charge region width and carrier collection efficiency. Under these optimized conditions, the photodetector reaches its optimum performance with a dark current of 1.1×10^-8 A, a photocurrent of 8.41×10^-6 A, and a responsivity of 0.21 A·W^-1. This research helps reduce the number of experiments and associated costs while preparing low-cost and high-performance ZnO photodetectors.