基于沟道耗尽行为的蓝宝石衬底AlGaN/GaN MIS-HEMT多场板缺陷诊断

This article presents a comprehensive study of the channel depletion behavior in depletion-mode AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with a triple-field-plate (tri-FP) structure on sapphire substrates, alongside an analysis of defect states within the device. High-voltage gate capacitance–voltage (CV) and high-voltage drain CV measurements reveal distinct stepwise changes in the CV characteristics, which are analyzed using a capacitor distribution model and TCAD simulations to identify 2DEG depletion mechanisms at the AlGaN/GaN interface and within the GaN channel layer. The impact of defects is further characterized by time-dependent recovery tests and CV hysteresis measurements, which demonstrate the influence of voltage stress on defect states. Additionally, frequency-dependent CV measurements highlight the presence of deep-level defects in the AlGaN and GaN layers, while temperature-dependent tests show that increasing temperatures lead to 2DEG diffusion, weakening the stepwise CV characteristics. These findings provide critical insight into the behavior of GaN HEMTs and offer guidance for optimizing their structure and performance in high-stress and high-temperature environments.