AlGaN/GaN two-dimensional electron gas Schottky barrier photodiodes with multiple Mg_xN_y/GaN layers

In this study, AlGaN/GaN two-dimensional electron gas (2DEG) heterostructures were grown by metal organic chemical vapor deposition (MOCVD). It was found that we could reduce reverse leakage current and provide high-voltage operation by introducing multiple Mg_xN_y/GaN layers into the conventional Schottky barrier photodiodes (SBPD). An atomic force microscopy (AFM) scan image showed that surface pits of TD terminations were hardly observed as the multiple Mg_xN_y/GaN layers were grown before subsequently depositing a high-temperature (HT) AlGaN/GaN epitaxial layer. A larger Schottky barrier height (Φ_B) and smaller ideality factor (n) extracted from the current-voltage (I-V) curve for SBPD with multiple Mg_xN_y/GaN layers also suggested that better crystal quality and rectifying properties were achieved. The larger value of Φ_B might be explained by the reduction of the TD density and interface state (IS) density.