Reverse-bias and ESD instabilities of InGaN-based LEDs

With this paper we give an overview on the degradation mechanisms of InGaN-based LEDs submitted to reversebias and to Electrostatic Discharge (ESD) events. The analysis was carried out on multi-quantum well LED chips, by means of electrical and optical characterization techniques. Results demonstrate that: (i) under reversebias conditions, current conduction occurs through localized paths, correlated to the presence of structural defects; (ii) exposure to reverse-bias can induce a significant degradation of the electrical properties of the LEDs, consisting in an increase in reverse-current, and in a corresponding decrease in the breakdown voltage; (iii) degradation is due to the generation/propagation of point defects at pre-existing defective sites; (iv) defective paths responsible for leakage current conduction represent potential failure regions under reverse-bias Electrostatic Discharge events. Material and device properties must be carefully optimized in order to obtain reliable operation for InGaN-based LEDs.