Numerical investigation of split-decoupled gate design for threshold voltage stabilization in p-GaN HEMT

Abstract This study presents an effective approach for stabilizing the threshold voltage ( V th ) through the development of an innovative split-decoupled gate p-GaN high electron mobility transistor (SDG-HEMT) architecture, which utilizes spatially differentiated gate contacts. The proposed design features an embedded dual-contact configuration comprising a Schottky gate contact and an ohmic gate contact. Under high drain voltage operation, the architecture achieves three synergistic stabilization mechanisms: (i) capacitive decoupling of gate-drain coupling effects, (ii) charge shielding enabled by selective etching of the p-GaN barrier layer, and (iii) efficient charge dissipation via the ohmic contact pathway. Numerical simulations reveal a remarkable 76% suppression of V th drift under 200 V drain bias compared to conventional Schottky-contact p-GaN HEMT. Parametric investigations further demonstrate a direct dependence of stabilization performance on recess depth ( T b ), with V th drift exhibiting a distinctive non-monotonic evolution: as the T b increases, the V th drift initially decreases and subsequently stabilizes. These findings provide fundamental insights into gate engineering strategies for HEMT reliability enhancement and represent a significant paradigm shift in high-voltage microelectronics design.