Understanding the degradation processes of GaN based LEDs submitted to extremely high current density. (September 2017)

• Record Type: Journal Article
• Authors: Renso, N.; Meneghini, M.; Buffolo, M.; De Santi, C.; Meneghesso, G.; Zanoni, E.
• Is Part Of: Microelectronics and reliability. Volume 76/77(2017)
• Page Start: 556
• Page End: 560
• Publication Date: 2017-09
• Subjects: LED -- Light-emitting-diode -- GaN -- Degradation processes -- Current crowding; Electronic apparatus and appliances -- Reliability -- Periodicals; Miniature electronic equipment -- Periodicals; Appareils électroniques -- Fiabilité -- Périodiques; Équipement électronique miniaturisé -- Périodiques; Electronic apparatus and appliances -- Reliability; Miniature electronic equipment; Periodicals; 621.3815
• DOI: 10.1016/j.microrel.2017.06.044
• Languages: English
• ISSNs: 0026-2714

Abstract

Abstract: This work presents the first analysis of the degradation mechanisms induced by extremely high current densities on green InGaN-based LEDs. To this aim, bare-chip LEDs were submitted to current step-stress, until catastrophic failure. We identified a current density threshold, around 260 A/cm 2, beyond which the devices start degrading, showing an increase in leakage current both in reverse and forward bias regimes. Moreover, a current crowding effect was detected on the degraded samples by electroluminescence measurements. A lumped element model was developed to describe the effects of stress. Results suggest that localized power dissipation, due to high current density flow under the anode pad, induces the formation of shunt paths and, eventually, leads to the catastrophic failure of the LEDs. Highlights: Analysis of the degradation mechanisms induced by extremely high current densities. Current threshold was identified beyond which the devices start degrading. Leakage current increase both in reverse and forward bias regimes during the stress. Electroluminescence measurements detected the current crowding effect. A lumped element model was developed to describe the effects of stress test.