Performance stability of high‐power III‐nitride metal‐oxide semiconductor‐heterostructure field‐effect transistors

Abstract

Record high RF power densities up to 30 W/mm have been recently achieved using AlGaN/GaN Heterostructure Field-Effect Transistors (HFETs). These results exhibit the promise of III-Nitride HFETs for high-power microwave applications. However the output RF power of these devices was found to degrade with the operation time. Gate leakage current in conventional HFETs is a major contributor to device instability and failure. We previously reported on the development of Metal-Oxide-Semiconductor Insulated gate HFETs (MOSHFETs) with gate leakage currents four to six orders of magnitude lower than those of the HFETs. The MOSHFETs has demonstrated a significant performance improvement as compared to conventional HFETs resulting in higher channel currents and RF powers. In this study, we present the first comparative experimental evaluation of the HFET and MOSHFET lifetime at room and elevated temperatures. The room temperature HFET stability lifetime as high as 2.4 years is estimated. We also present the detailed study of the HFETs stabilization and failure mechanisms. The pronounced similarity of the mechanisms of device degradation and current collapse is demonstrated. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)