Preliminary reliability assessment and failure physical analysis on AlGaN/GaN HEMTs COTS

GaN based FETs have demonstrated high microwave performance since several years, and exhibit attractive potential for microwave power source in electronic warfare and military radar application, and also for civilian telecommunication applications like wireless basestations, Wi-Max, Wi-Fi as well. Up to now, the main challenge remaining for this technology is the proof of good reliability. The Information Warfare Technology Center (CELAR) launched a GaN COTS assessment campaign in order to achieve a state of the art on this topic. In this paper, we presented and discussed the first results of a life test evaluation on HFET GaN/AlGaN structure on silicon substrate and the first results of investigations by physical analysis on a failed device. These preliminary reliability investigations show all the importance of reliability tests conditions applied in order to compare reliability results and also, the benefits of a screening to obtain representative technology quality of the batch of sample before stress. Our investigations on failure analysis by STEM around the gate area of a failed device show defects which could be responsible of a degradation of the Schottky gate. (C) 2007 Elsevier Ltd. All rights reserved.