Degradation mechanisms of bias stress on nitride-based near-ultraviolet light-emitting diodes in salt water vapor ambient

Abstract

Degradation mechanisms of nitride-based near-ultraviolet (near-UV) light-emitting diodes (LEDs) were systematically analyzed by applying forward- and reverse-bias stresses to them in a salt water vapor ambient. The surface temperature of the forward-bias stress sample was higher than that of the reverse-bias stress sample. The high temperature of the forward-bias stress sample accelerated the chemical reaction of the device structure with salt water vapors and led to faster degradation. Composition analyses of the sample surface and cross-section were conducted to investigate the failure mechanism. The analyses results indicated that the erosion of the indium-tin-oxide layer enhanced the diffusion of the conducting metal into the LED crystal. The proposed method can effectively characterize the quality of near-UV LEDs in a short duration.