MSM Solar-Blind Ultraviolet Detector Incorporating Asymmetric Contact Electrodes Fabricated on AlₓGa₁–ₓN Hetero-Epilayers

In this work, we investigate the ability of a newly fabricated metal-semiconductor–metal (MSM) solar-blind ultraviolet (UV) photodetector (PD). Three AlXGa1–XN films with different Al content were used to form heterostructures, and different metal stacks were deposited on their two sides to achieve asymmetric contact electrodes. The device exhibited a dark current of
$2.53\times 10^{-{8}}$
A and a peak responsivity of 2.86 at -9 V, while corresponding dark current and peak responsivity at 9 V are
$4.90\times 10^{-{7}}$
A and 20.19 A/W, respectively. Furthermore, its response speed was faster under reverse bias than forward bias. Two-dimensional device simulations were used to obtain the bias-dependent energy bands, electric fields, and carrier concentrations to explain the discrepancy of detection performances between different bias polarities.