Aging-Induced Mg Cluster Observation in GaN-Based Lasers by Atom Probe Tomography

Gallium nitride (GaN)-based lasers, spanning emission wavelengths from ultraviolet to green, are widely used as light sources in many application domains. Despite their widespread usage, the comprehensive analysis of atomic-level degradation remains challenging primarily due to limitations in metrology techniques. In this study, we investigated the aging-induced magnesium (Mg) clusters in GaN-based lasers utilizing atom probe tomography. Notably, we have identified Mg clusters of several nanometers in size within the p-type aluminum gallium nitride (p-AlGaN) cladding layer of aged lasers, marking the first observation of such clusters in this context. The presence of Mg clusters induces light scattering and absorption within the cladding layer, contributing to an increase in internal loss and a decrease in slope efficiency. Furthermore, our findings underscore the efficacy of atom probe tomography as a potent technique for conducting atomic-level device failure analysis of semiconductor devices.