Investigation of Dynamic-QGD on Enhancement-Mode AlGaN/GaN MIS-HEMTs with SiNx Passivation Dielectric

Effect of bulk states in passivation dielectrics on dynamic gate-drain capacitance (CGD) and QGD of GaN-based power devices, was systematically investigated by inductive-load switching, voltage/temperature-dependent capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements. DLTS measurements confirm that the bulk states with activation energy (EC-ET) higher than 1.1 ± 0.05 eV, presents in SiNx passivation dielectric grown by low-pressure chemical vapor deposition (LPCVD). It is revealed that the trapping/de-trapping of these bulk states will give rise to QGD instability in T-shape gate enhancement-mode (E-mode) AlGaN/GaN MIS-HEMTs (metal-insulator-semiconductor high-electron-mobility transistors), leading to undesirable degradation of switching characteristics.