High-Power GaN-Based Blue Laser Diodes Degradation Investigation and Anti-aging Solution

Abstract

Gallium nitride (GaN)-based semiconductor laser diodes (LDs) have garnered significant attention due to their promising applications. However, high-power LDs face serious degradation issues that limit their practical use. This study investigates the degradation factors of 437 nm and 6.3 W LDs by comparing light–current–voltage (L–I–V) characteristics, transmission electron microscopy (TEM), cathodoluminescence (CL), and secondary ion mass spectroscopy (SIMS) before and after 1000-h aging. The diffusion of mirror coating from the resonant cavity surface is identified as a key factor contributing to high-power LD degradation, which has not been reported in milliwatt-level LDs. Meanwhile, the mechanisms behind the LD degradation are profiled and summarized together with the diffusion and other factors. On basis of the mechanism exploration, an anti-aging technology for high-power GaN-based LDs is developed by using aluminum nitride for passivation layer and sapphire materials for mirror film. This anti-aging technology has been verified, and a nearly ten-time degradation suppression is achieved from 1000 h. This study elucidates the degradation mechanisms of high-power GaN LDs and provides an effective technology to extend their lifespan, thereby prompting the practical applications of high-power LDs.