Failure Mechanisms of GaN Metal-Semiconductor-Metal

This paper proposes a new method of analyzing the reliability of GaN metal-semiconductor-metal (MSM) photode- tectors (PDs). This paper analyzes and characterizes the reliability of GaN MSM PDs with TiW electrodes under different stressing conditions. Controlling the temperature and injection current makes it possible to stress the device and evaluate its characteris- tics after stressing. Results show that the dark current and respon- sivity of PDs change with the aging temperature and current. The aging current density is a dominant factor in reliability. This paper also conducts failure analysis to clarify the PD failure mechanisms. Optical microscope inspection shows that burned-fail electrodes are a major cause of failure. Photoluminance analysis shows that the decline of GaN crystal quality is another cause of failure. Index Terms—GaN, photodetectors (PDs), reliability, metal- semiconductor-metal (MSM).