AlGaN/GaN High Electron Mobility Transistors with a p-Type GaN Cap Layer

In this work, AlGaN/GaN HEMTs with different types of p-GaN cap layers were fabricated and investigated. The p-GaN cap layer used in this study was for passivation study instead of forming enhancement-mode operation. The differences in p-GaN cap layers were Mg-doping concentration (1×1019 and 3×1019 cm-3) and thickness (5 and 8 nm). Device with p-GaN cap of 8-nm and Mg-doping of 3×1019 cm-3 showed the lowest gate leakage current, highest on/off current ratio (1.02×106), highest breakdown voltage and least current collapse characteristics.