Improved Responsivity Drop From 250 to 200 nm in Sputtered Gallium Oxide Photodetectors by Incorporating Trace Aluminum

A solar-blind photodetector (PD) based on the cosputtered aluminum-gallium oxide (AGO) material after thermal annealing at 900 °C has been demonstrated using a metal-semiconductor-metal structure. By incorporating optimum trace aluminum (Al), the AGO PD shows the peak responsivity (at 230 nm) of 1.38 A/W under a bias voltage of 5 V, which is 53.61 times greater than that of the PD from the gallium oxide (GO) film without incorporating any Al content. The photocurrent, dark current, and detectivity (at 5 V and 230 nm) of AGO PD are also improved to be 46.4, 0.83, and 96.5 times, respectively, greater than those of GO one. Unlike conventional GO samples revealing obvious drop in spectral response from 250 to 200 nm, the AGO PD with an Al/(Al + Ga) ratio of 1.8% exhibits a nearly flat responsivity curve in the deep ultraviolet region. This improvement is significant compared with previous reports for the GO and AGO PDs by other growth methods.