Fig. 1. (a) Transfer and (b) off-state blocking voltage characteristics of the GaN MIS-HEMT.

Fig. 2. (a) Test diagrams of negative bias stress and (b) time-dependent breakdown with V_GS = −295 V, −300 V, −305 V, respectively, and (c) lifetime extrapolation for 20 years based on 1/E model with failure rate of 63.2% and 0.01%.

Fig. 3. (a) Test diagrams of off-state stress and (b) time-dependent breakdown during off-state stress with V_DS = 280 V and V_DS = 270 V @V_DG = 295 V.

Fig. 4. (a) The comparison of time-dependent breakdown between negative gate voltage stress and off-state stress. (b) Two sudden increasing trends of gate leakage occur during both stress conditions.

Fig. 5. Breakdown time distribution (β) of (a) negative gate bias with V_GS = −295 V, −300 V, −305 V, respectively and (b) off-state stress with V_DS = 280 V and V_DS = 270 V @V_DG = 295 V.

Fig. 6. Simulation of electric field distribution for rapid breakdown under (a) negative bias stress @V_DG = 295 V and (b) off-state stress @V_DG = 295 V. (c) Extraction of electric field distribution at the cutline of 10 nm below SiN_x/AlGaN interface for both of the two stress conditions.

Fig. 7. The evolution of threshold voltage and on resistance during stress and recovery conditions of V_GS = −200 V, V_DS = 0 V, and V_GS = −15 V, V_DS = 185 V @V_DG = 200 V.

Fig. 8. The evolution of leakage during (a) negative gate bias at V_GS = −200 V, V_DS = 0 V @V_DG = 295 V and (b) off-state stress at V_GS = −15 V, V_DS = 185 V @V_DG = 200 V.

Fig. 9. The schematic mechanism for the negative bias stress (a)–(c) and off-state time-dependent breakdown process (e)–(g).

Fig. 10. Transfer characteristics and I_GS before stress and after adequate recovery of (a) negative bias stress at V_GS = −200 V, V_DS = 0 V @V_DG = 200 V and (b) off-state stress at V_GS = −15 V, V_DS = 185 V @V_DG = 200 V.