Charge compensation impact on the access region resistance in AlGaN/GaN devices

In this paper, the impact of the charge compensation on the access region resistance (RACC) distributions is systematically investigated in AlGaN/GaN devices. Based-on the transmission line model (TLM) method, the RACC in AlGaN/GaN devices is extracted and compared with/without the plasma-enhanced atomic-layer-deposition (PEALD) Al2O3 passivation. The PEALD-Al2O3 could supply additional positive charges at the AlGaN surface, which serves as the effect of charge compensation. With the increased positive charge density at the passivation/AlGaN interface, the surface potential (φS) of the AlGaN barrier is significantly reduced, leading to the two-dimensional-electron-gas (2DEG) density improvement at the GaN channel layer. Supported by the device's fabrication and simulation, the charge compensation impact on the RACC is verified in both the p-GaN sample after etching and the AlGaN/GaN sample without etching. The results of this work could provide beneficial guidance to design the low on-resistance (RON) AlGaN/GaN devices.