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 I
_D
(V
_G
) and C(V
_G
) pBTI shifts on GaN-on-Si E-mode MOS-channel HEMTs, under various gate voltage stresses (V
_GStress
) and temperatures (T). A new experimental setup using ultra-fast and simultaneous I
_D
(V
_G
) and C(V
_G
) measurements enables to monitor the threshold voltage V
_TH
drift through two metrics, VTHI and VTHC. Experimental pBTI results depict a difference between VTHI and VTHC, such as . TCAD simulations support that ID(V
_G
) shift (VTHI) is related to charge trapping in Al
₂
O
₃
gate oxide defects at the gate corners regions while C(V
_G
) shift (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 Al
₂
O
₃
defects density is more important at the gate corners than at the gate bottom.