Reliability of GaN HEMTs: current status and future technology

In this paper, we describe highly reliable GaN high electron mobility transistors (HEMTs) for high-power and high-efficiency amplifiers. First, we present the reliability mechanisms and progress on the previously reported GaN HEMTs. Next, we introduce our specific device structure for GaN HEMTs for improving reliability. An n-GaN cap and optimized buffer layer are used to realize high efficiency and high reliability by suppressing current collapse and quiescent current (I_dsq)-drift. Finally, we propose a new device process around the gate electrode for further improvement of reliability. Preventing gate edge silicidation leads to reduced gate leakage current and suppression of initial degradation in a DC-stress test under high-temperature and high-voltage conditions. Gate edge engineering plays a key role in reducing the gate leakage current and improving reliability.