High-Performance Normally-Off Operation p-GaN Gate HEMT on Free-Standing GaN Substrate

Abstract

A normally- OFF AlGaN/GaN high-electron-mobility transistor (HEMT) with p-GaN gate was fabricated on free-standing GaN substrate. The self-terminated etching technology was achieved by combining with AlN stop layer and SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> -based etching gas. Compared with HEMT on Si substrate (Si-HEMT), the HEMT on GaN substrate (GaN-HEMT) demonstrated the higher current density, lower subthreshold swing (SS), lower drain leakage current, and lower static and dynamic ON-resistance that were ascribed to the lower dislocation and less defect on free-standing GaN substrate. Meanwhile, the excellent <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\mathrm{th}}$ </tex-math></inline-formula> stability up to 175 °C and uniformity was demonstrated. Also, higher breakdown voltage (BV) of 683 V was measured, which was higher than 507 V for Si-HEMT. Hence, a normally- OFF AlGaN/GaN HEMT on free-standing GaN substrate shows good potential in power application.