Investigation of AIGaN/GaN MISHEMTs with Varied AIGaN Barrier Depths via a Low Damage ALE Process

This study successfully demonstrates the low-damage Atomic Layer Etching (ALE) process in enhancing the performance of recessed gate Metal-Insulator-Semiconductor High Electron Mobility Transistors (MIS-HEMTs). Specifically the AlGaN/GaN recessed gate MIS-HEMT with a remaining thickness of 5 nm exhibited outstanding characteristics including the drain current (I_Dmax)of 400 mA/mm competitive threshold voltage (V_TH) of the on/off current ratio of and the high breakdown voltage (BV) of 830 V. Further the varying thicknesses of AlGaN recessed gates (2 3 and 5 nm) MIS-HEMTs were fabricated. Recessed gate MIS-HEMT with AlGaN remaining 5 nm thickness achieved a high BV capability of 830 V at of 1 imm exceeding the AlGaN remaining 3 nm and 2 nm thicknesses which reached only 120 V and 75 V respectively. To investigate the significant BV difference between the 5 nm and 3 nm AlGaN thicknesses the Technology Computer-Aided Design (TCAD) simulation was employed. Analysis of the electric field distribution at a drain voltage (Vn) of 50 V shows a clear peak near the gate edge with 3 nm remaining AlGaN thickness showing a higher electric field than 5 nm thickness.