Current Collapse Suppression by Silicon Substrate Removal Technique in AlGaN/GaN HEMT

Abstract

In this study, we present a local substrate removal approach to suppress current collapse phenomenon for Al-GaN/GaN HEMT. For comparison, we made a conventional HEMT without substrate removal process. Result shows that the removal process has no negative effect on DC IV performance, instead, the drain current increase slightly after Si substrate removal, which may result from stress release due to lattice mismatch between Si and GaN. Then, pulse IV measurement is conducted using Keithley 2601a and Keithley 2651a to simultaneously provide gate and drain voltage pulse. Measurement results show that current collapse is strongly suppressed after Si substrate removal. Our findings suggest that current collapse may be related to not only buffer trap but also substrate trap, and Si substrate removal technique is an very effective way to mitigate current collapse phenomenon