Enhanced Dynamic V TH Stability by Inserting a Hole Release Path in the Barrier for Normally off HEMTs with Regrown p-GaN Gate

This study proposes a GaN insertion layer (IL) as a hole release path in the AlGaN barrier for regrown p-GaN gate HEMTs. With the GaN IL, the MOCVD thermal decomposition process can also enable self-termination of gate recess etching at the surface of the bottom AlGaN layer, which achieves a remarkable improvement in enhancing the uniformity of threshold voltage (VTH) across the entire wafer. The standard deviation of VTHis reduced to 0.07 V when compared to traditional devices without the GaN IL. Notably, pulsed I-V measurements are carried out to characterize the dynamic VTHshift. For the HEMTs with a GaN IL, the dynamic VTHshift is significantly suppressed to within 0.2 V. To gain insights into the mechanism underlying this low dynamic VTHshift, TCAD simulation is also carried out to confirm the effectiveness of the GaN IL as a hole release path. This work gives new prospects for enhancing dynamic VTHstability in p-GaN gate HEMTs.