Failure Physics and Reliability of GaN-Based optoelectronic devices

With this work we review the failure modes and mechanisms of GaN-based optoelectronic devices. A number of reliability tests are presented and specific degradation mechanisms of state-of-the-art optoelectronic devices are analyzed. In particular, we describe recent results concerning (i) the degradation of the active layer of LEDs and lasers, due to the increase in non-radiative recombination; (ii) the degradation of LEDs submitted to reverse-bias stress tests; (iii) the catastrophic failure of advanced LED structures, related to Electrostatic Discharge (ESD) events; (iv) the degradation of the ohmic contacts of GaN-based LEDs; (v) the degradation of the optical properties of the package/phosphors system of white LEDs. The presented results provide important information on the weaknesses of LED technology and on the design of procedures for reliability evaluation. Results are compared with literature data throughout the presentation.