Reliability limitations from crystal defects in thick GaN epitaxial layers

The vertical power switching devices made from GaN and related nitride semiconductors contain a high density of crystal defects, especially in the thick epitaxial drift layers. Most of these defects are present initially in starting wafers and some are generated during device processing. There is little conclusive evidence so far on the exact role that the crystal defects play on device performance, manufacturing yield, and more importantly, longterm field-reliability especially when devices are operating under extreme stressful high voltage environments. This paper provides the progress of characterization of thick GaN power semiconductor material epitaxial layers and the potential impact crystal defects may have on high-density power switching electronics. The investigation also presents simulated results of the electric field distribution through thick epitaxial (greater than 10 mm) region.