Understanding the Role of Dislocation Defects of GaN HEMT under Short-Circuit Stress Through Transient Thermal Characterization

Gallium nitride (GaN) high electron mobility transistor (HEMT) devices are prone to rapid failure after repetitive short-circuit (SC) stress under high bus voltage conditions. The dislocation defects at the substrate interface play a critical role in inducing device degradation and thermal breakdown failure. However, the mechanisms of dislocation defect formation under SC stress and their influence on the SC capability of GaN HEMTs remain unclear. This article presents a novel method based on transient thermal resistance characterization to monitor the evolution of dislocation defects within GaN HEMT devices. Meanwhile, a thermal model is developed to illustrate the influence of dislocation defects on the thermal characteristics of the device. By analyzing the structure function of the GaN HEMT before and after SC stress, the accumulation of previously imperceptible defects is translated into observable changes in thermal resistance curves. The degradation of thermal characteristics of GaN HEMT devices under varying bus voltages and SC pulse durations are investigated. Experimental results demonstrate that the transient thermal characterization method effectively identifies regions of dislocation defect accumulation, quantifies the extent of defect accumulation, and provides a comprehensive understanding of damage evolution within GaN HEMTs under repetitive SC stress.