Degradation of on-current in 4 kV β-Ga ₂O ₃ trench Schottky barrier diodes under high voltage step stressing

Reliability of β-Ga2O3 based trench Schottky barrier diodes with a breakdown voltage of 4 kV and a Baliga's figure of merit of ∼1 GW/cm2 is reported. The devices were stressed with reverse voltages up to 3 kV in increasing steps of 250 V, followed by an evaluation of the on-state characteristics after each step-stress. The step-stress testing revealed an increase in on-state resistance of <3% when stressed up to 2.25 kV but degrades to 13% when stressed at 3 kV, recovering fully after 3 h rest time. The degradation in on-state characteristics (current collapse) under high reverse bias stress is attributed to the negative charge trapping near the bottom corner of the fins, which reduces the net conductive area of the fins. The current degradation could be replicated through drift-diffusion simulations, with trapped charge density of ∼3 × 1012 cm−2 required to match 13% degradation observed experimentally. This work highlights the critical influence of dielectric properties and charge trapping on the reliability and performance of ultra-wide bandgap materials like Ga2O3.