Rapid detection of capture and emission processes in surface and buffer traps: Understanding dynamic degradation in GaN power devices

Abstract

This study utilized a rapid detection technique, Isothermal Capture Transient Spectroscopy (ICTS), to identify and evaluate defects related to GaN device surface and buffer traps, and investigated the mechanisms by which they affect the dynamic performance of GaN based devices. Interface states and dielectric bulk traps were analyzed, unveiling distinctive device behavior under positive gate pulse-biased ICTS. The observed S-shaped threshold voltage (VTH) instability and dynamic gate-drain capacitance (CGD) issues were directly associated with these interface states and bulk traps. Negative gate pulse-biased ICTS revealed the presence of logarithmic electron trapping originating from extended electron traps, and spatial wide distributed hole traps within the GaN buffer layer, significantly impacting the dynamic on-resistance (RON) during off-state stress of the devices. The rapid assessment capabilities of this method provide a valuable tool for optimizing GaN epitaxy and manufacturing processes.