Power limitation due to premature breakdown in alGaN/GaN HFETs

摘要

A systematic investigation of high field prebrakdown and breakdown phenomena of AlGaN/GaN Heterojunction Field Effect Tranistors (HFETs) is presented. The breakdown process was studied as a function of various parameters such as applied electric field, material layer structure, semiconductor surface conditions, ambient dielectric, and test conditions. Experimental evidence of a breakdown mechanism, distinct form the bulk/subsurface breakdown, namely on-surface breakdown or surface flashover is presented. A presented. A practical, unambiguous way of identifying device failure by surface flashover is proposed. Surface flashover between gate and drain contact edges is proosed as the main mechanism initiating premature breakdown in thse devices leading to a significant reduction of their power capability.