Degradation mechanism of InAlN/GaN based HFETs under high electric field stress

Abstract

Degradation of InAlN/GaN based HFETs under stress for four bias conditions, namely, on-state high field stress (hot phonon, hot electron and self heating effect), off-state high field stress (hot electron effect), onstate low field stress (self heating effect), and reverse gate bias stress (inverse piezoelectric effect) has been examined. The degradation is characterized by monitoring electrical properties, such as, drain current reduction, gate lag, and low frequency noise. On-state high field stress has shown more than 50% reduction in the drain current and approximately 25-30 dBc/Hz increase in low frequency noise after 25 hours of stress, while other stress conditions led to much lesser degradation. It is demonstrated that the major degradation mechanism in InAlN/GaN HFETs is the hot-phonon and hot-electron effect in the realm of short term effects.