Degradation mechanisms in GaN light-emitting diodes undergoing reverse-bias operations in water vapor

Abstract

Reverse-bias testing light-emitting diodes (LEDs) enables devices to be rapidly screened for weaknesses and pinpoints the origins of failure. In this study, GaN LED reliability was examined by reverse-bias, stressing the device in water vapor. The LED failure origins were investigated using electrical characterizations, optical measurements, and material analyses, namely, focused ion beam deposition, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results indicated that diffused Au atoms from the surface of the LED can increase leakage current, generate high electric fields, and degrade device performance levels. Moreover, hot-carrier-induced emissions for LEDs undergoing reverse-bias operations confirmed that gold distribution caused by the water vapor generated high electric fields.