Influence of Ammonia in the Deposition Process of SiN on the Performance of SiN/AlGaN/GaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors on 4-in. Si(111)

The influence of ammonia (NH3) in the plasma enhanced chemical vapor deposited (PECVD) SiN on the performance of SiN/AlGaN/GaN metal?insulator?semiconductor high-electron-mobility transistors (MIS-HEMTs) were studied by measuring dc, small signal, current collapse, and breakdown voltage (BVgd) characteristics. The MIS-HEMTs with SiN (NH3?SiN) deposited using NH3 and SiH4 exhibited better device performances when compared to AlGaN/GaN HEMTs and MIS-HEMTs with SiN deposited using N2 and SiH4 (NH3-free SiN). Due to the low gate-leakage current, enhanced BVgd was observed on both NH3?SiN (27.4%) MIS-HEMTs and NH3-free-SiN (13.7%) MIS-HEMTs when compared to HEMTs. The enhancement of cut-off frequency (fT) and suppression of drain current collapse were also observed on both types of SiN/AlGaN/GaN MIS-HEMTs. The improved device characteristics of MIS-HEMTs are possibly due to the formation of good quality interface between NH3?SiN and AlGaN.