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).