Exploring the DC reliability metrics for scaled GaN-on-Si devices targeted for RF/5G applications

Abstract

GaN-channel based transistors are ideally suited for RF/5G applications and also provide the promise of monolithic integration on a conventional Si-platform. Due to the wide scope of high electron mobility GaN transistor architectures, their reliability assessment is essential to ensure their successful deployment in low-power applications such as mobile computing devices, as well as high-power applications such as autonomous vehicles and base stations. We identify the most important DC-reliability metrics necessary for fair benchmarking of future GaN-on-Si RF transistors. A detailed analysis of the shortlisted DC-reliability parameters for three device types, namely MOSFETs, MOSHEMTs/MISHEMTs and HEMTs is presented. MOSHEMT/MISHEMT is identified as the most robust device architecture, due to the presence of a barrier layer alleviating the impact of certain degradation mechanisms. Defect distributions in the gate-stack of MOS devices are extracted using defect band modelling technique. MOSHEMT devices are shown to undergo negative and positive Bias Temperature Instability (BTI) under specific ranges of positive gate-overdrive, thereby demonstrating the importance of correctly estimating the oxide field for MOSHEMT devices. Degradation map methodology is partially developed to distinguish the different gate-oxide degradation mechanisms and model the device lifetime pertaining to each of the mechanisms.