Study on the difference between ID(VG) and C(VG) pBTI shifts in GaN-on-Si E-mode MOSc-HEMT

In this study, we investigate the difference between ID(VG) and C(VG) pBTI shifts on GaN-on-Si E-mode MOS-channel HEMTs, under various gate voltage stresses (VGStress) and temperatures (T). A new experimental setup using ultra-fast and simultaneous ID(VG) and C(VG) measurements enables to monitor the threshold voltage VTHdrift through two metrics, Δ VTHI and ΔVTHC. Experimental pBTI results depict a difference between Δ VTHI and Δ VTHC, such as Δ VTHI < Δ VTHC. TCAD simulations support that ID(VG) shift (Δ VTHI) is related to charge trapping in Al2O3gate oxide defects at the gate corners regions while C(VG) shift (Δ VTHC) is mainly ascribed to the gate bottom, due to the presence of a back-barrier layer in the epitaxy. These previous results enable to deduce that the Al2O3defects density is more important at the gate corners than at the gate bottom.