Robust SiNx/AlGaN Interface in GaN HEMTs Passivated by Thick LPCVD-Grown SiNx Layer

Low-pressure chemical vapor deposition (LPCVD) technique is utilized for SiN_x passivation of AlGaN/GaN high-electron-mobility transistors (HEMTs). A robust SiN_x/ AlGaN interface featuring high thermal stability and well-ordered crystalline structure is achieved by a processing strategy of “passivation-prior-to-ohmic” in HEMTs fabrication. Effective suppression of surface-trap-induced current collapse and lateral interface leakage current are demonstrated in the LPCVD-SiN_x passivated HEMTs, as compared with conventional plasma-enhanced chemical vapor deposition-SiN_x passivated ones. Energy dispersive X-ray spectroscopy mapping analysis of SiN_x/AlGaN interfaces suggests the interface traps are likely to stem from amorphous oxide/oxynitride interfacial layer.