Dynamic-QGD of Enhancement-mode AlGaN/GaN MIS-HEMTs Induced by Bulk/Interface States in SiNx Passivation Dielectric

Effect of bulk/interface 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). DLTS measurements confirm that a continuous distributed bulk state 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.