16.2 Failure Mechanisms in AlGaN/GaN HEMTs Irradiated with 2MeV Protons

GaN high electron mobility transistors (HEMTs) have shown the potential to be extremely tolerant of the space radiation environment. AlGaN/GaN HEMT structures on three different substrates were exposed to proton irradiation at fluences up to 6x10 14 cm -2 , which resulted in a 30% reduction in mobility and saturation current density. Dynamic ON-resistance measurements demonstrated increased degradation by a factor of 10 under off-state quiescent voltage stress conditions. High resolution transmission electron microscopy revealed a radiation-induced void under the gate metallization, indicative of a Kirkendall effect. INTRODUCTION As a wide bandgap semiconductor, the GaN-based materials system is attractive for next-generation power devices, including RF amplifiers, high voltage power switches, and high breakdown voltage diodes. Such devices have a wide range of immediate Naval applications, such as high-power satellite communications and radar, unmanned underwater and aerial vehicles, ship drive components, and hybrid vehicle inverters. A fundamental understanding of the reliability and failure mechanisms in these devices is critical to further technology development and insertion. Of particular interest is the potential to be highly resistant to radiation damage, making them ideal for use in microwave power amplifiers and DC/DC converters in space-based applications [1-3]. To investigate the mechanisms of radiation-induced degradation in AlGaN/GaN HEMTs, 2MeV protons were used to simulate the space radiation