In-Situ Characterization of the Evolution of Defects in AlGaN/GaN HEMTs in the On-state and Off-state condition

Nitride semiconductors offer many unique and beneficial properties for new generation electronic devices [1]. GaN-based HEMTs are contenders for replace existing Si and GaAs devices in high-power RF applications. AlGaN/GaN High Election Mobility Transistors (HEMTs) are devices designed for applications where high-power and high-frequency devices are needed. AlGaN/GaN HEMTs take advantage of a two-dimensional electron gas (2DEG) that forms at the AlGaN/GaN interface to create a layer of highly mobile electrons that are easily modulated by an applied bias. Unfortunately, high-power operating conditions often result in unpredictable and catastrophic device degradation [2]. In our previous ex-situ work, we observed the formation of defects under the drain side edge of the gate during bias. The amount of defects present increased with bias duration and this was related to changes in ID and strain near the AlGaN/GaN interface [3]. However, the formation mechanism of these defects has not been fully investigated as a function of operating time. As such, quantitative analysis on the evolution of defects is needed to further understand device failure mechanisms.