Improved I on /I off Current Ratio and Dynamic Resistance of a p-GaN High-Electron-Mobility Transistor Using an Al 0.5 GaN Etch-Stop Layer.

In this study, we investigated enhance mode (E-mode) p-GaN/AlGaN/GaN high-electron-mobility transistors (HEMTs) with an Al 0.5 GaN etch-stop layer. Compared with an AlN etch-stop layer, the Al 0.5 GaN etch-stop layer not only reduced lattice defects but engendered improved DC performance in the device; this can be attributed to the lattice match between the layer and substrate. The results revealed that the Al 0.5 GaN etch-stop layer could reduce dislocation by 37.5% and improve device characteristics. Compared with the device with the AlN etch-stop layer, the p-GaN HEMT with the Al 0.5 GaN etch-stop layer achieved a higher drain current on/off ratio (2.47 × 10 7 ), a lower gate leakage current (1.55 × 10 -5 A/mm), and a lower on-state resistance (21.65 Ω·mm); moreover, its dynamic R ON value was reduced to 1.69 (from 2.26).