Barrier and doping co-engineering using graded AlGaN and step-Gaussian profiles for enhanced RF power performance in HfO2-based MOS-HEMTs

This work proposes a barrier and doping co-engineering framework for GaN metal–oxide–semiconductor high-electron-mobility transistors (MOS-HEMTs) utilizing a high- k HfO 2 gate dielectric. Three device architectures are systematically compared under identical lateral geometry: a conventional uniform-barrier MOS-HEMT (C-MOSHEMT), a vertically graded AlGaN-barrier MOS-HEMT (GB-MOSHEMT), and a co-engineered device integrating vertical barrier grading with a step-wise Gaussian approximation of barrier doping (GB-SG-MOSHEMT). The proposed GB-SG-MOSHEMT achieves a peak drain current of approximately 1.73 A/mm, a peak transconductance of approximately 0.53 S/mm, a reduced total gate capacitance of approximately 1.6 × 1 0 − 12 F/mm, a cutoff frequency of approximately 82 GHz, and a maximum oscillation frequency of approximately 81 GHz. Electric-field profiling and boost-converter circuit-level validation corroborate the device-level trends, confirming a steady output voltage of approximately 190 V. These results demonstrate that graded-barrier and step-Gaussian doping co-engineering provides an effective route to simultaneously optimize current drive, capacitance loading, and RF speed in HfO 2 -based GaN MOS-HEMTs.