Mechanistic insight and demonstration of antiferroelectric-gated enhancement-mode GaN HEMTs

Abstract

This work presents mechanistic insight into polarization-assisted charge trapping in GaN HEMTs and demonstrates an enhancement-mode (e-mode) device employing an antiferroelectric (AFE) Hf0.2Zr0.8O2 gate stack (AFE-HEMT). The AFE gate stack, featuring enhanced charge trapping capability and zero remnant polarization (Pr), allows complete utilization of trapped electrons for channel depletion, resulting in a stronger positive threshold voltage (VTH) shift compared with the ferroelectric (FE) gate stack. The AFE-HEMT achieves a VTH of 1.9 V, with a maximum drain current (ID_MAX) of 481 mA/mm and an on-resistance (RON) of 7.4 Ω mm. Incorporating a floating gate structure (AFE-FG-HEMT) further enhances VTH to 2.7 V with an RON of 6.5 Ω mm, significantly improves charge retention, and yields negligible VTH shift during positive bias stress, demonstrating a compelling pathway toward stable, normally off GaN power devices.