Characterization and reliability of GaN-based LEDs and lasers

With this paper we give an overview on the physical mechanisms responsible for the optical degradation of InGaN-based optoelectronic devices, LEDs and lasers. A number of reliability tests are presented and specific degradation mechanisms of state-of-the-art optoelectronic devices are analyzed. In particular, we present data on: (i) the degradation of the active layer of the devices; (ii) the role of defects in limiting the lifetime of optoelectronic devices; (iii) the role of the different driving forces (current, temperature, optical power) in determining the worsening of the electro-optical characteristics of LEDs and lasers; (iv) the role of structural defects in determining the failure of LEDs submitted to Electrostatic Discharge events. Presented results provide important information on the current weaknesses of InGaN technology, and on the design of procedures for reliability evaluation. Results will be compared to literature data throughout the paper, in order to provide arguments for a complete understanding of the topic.