Micro-Raman and SEM analyses of failed GaN HEMT multilayer architecture

The challenge of accurately diagnosing and understanding failure mechanisms in GaN power devices under high-stress conditions has been a persistent issue, particularly with respect to catastrophic failures difficult to detect through conventional electrical measurements. This study focuses on p-GaN-based high-electron-mobility transistors (HEMT) technology device, subjected to high-stress conditions, to analyze the entire device architecture and mainly the structure of the gate–source bridge. SEM analyses reveal significant structural damage, including cracks and voids, particularly near the metal interconnection lines and GaN buffer layers, whereas Raman spectroscopy highlights distortions in the wurtzite GaN crystal structure. By integrating the spectroscopic and morphological results, useful insights into the GaN device layers interested by the failure mechanisms are provided. These data are useful to optimize the multi-layer stacked structures and then to enhance the GaN HEMTs main characteristics.