Back Barrier Trapping Induced Resistance Dispersion in GaN HEMT: Mechanism, Modeling, and Solutions

Trapping in an impurity (e.g. Fe, C) doped back barrier (BB) causes pronounced on-resistance (R-on) dispersion of GaN HEMTs. We demonstrate that the BB trapping is alleviated by increasing 2DEG density N-sh in the GaN channel (similar to 50% increased N-sh results in similar to 30% less Delta R-on) and inserting an additional intrinsic AlGaN BB ( 100 nm AlGaN with similar to 50% less Delta R-on). We propose a novel flat-AlGaN-BB-energy-band designing criterion for the AlGaN/C-GaN BB combination.