Carbon-related pBTI degradation mechanisms in GaN-on-Si E-mode MOSc-HEMT

In this paper, threshold voltage V
_TH
instabilities under positive gate voltage stress (V
_GStress
) are thoroughly investigated on GaN-on-Si Enhancement-mode MOS-channel HEMTs. An analysis of pBTI transients performed at several V
_GStress
and temperatures (T) reveals two trap populations close to the Al
₂
O
₃
/GaN interface namely (1) C
_N
acceptors in the GaN substrate, and (2) defects in the Al
₂
O
₃
gate oxide. Both trap populations lead to V
_TH
instabilities via different underlying mechanisms as evidenced by TCAD simulations. At V
_GStress
<; 1.5 V, V
_TH
drifts are ascribed to C
_N
traps ionization localized at 0.8-0.9eV above the valence band (E
_v
). At higher VGstress, electron trapping also occurs in Al
₂
O
₃
defects leading to stronger V
_TH
degradation. DC & AC pBTI transients have been modeled using Capture Emission Time (CET) map approach, which allowed the identification of both trap populations. Temperature-dependent CET maps extraction reveals a strong activation of C
_N
traps with temperature, and confirms Arrhenius analysis consistency. This study provides a deep understanding of BTI reliability in GaN-HEMT technologies.