Stability and degradation of AlGaN-based UV-B LEDs: Role of doping and semiconductor defects. (September 2019)

• Record Type: Journal Article
• Authors: Piva, F.; De Santi, C.; Deki, M.; Kushimoto, M.; Amano, H.; Tomozawa, H.; Shibata, N.; Meneghesso, G.; Zanoni, E.; Meneghini, M.
• Is Part Of: Microelectronics and reliability. Volume 100/101(2019)
• Publication Date: 2019-09
• Subjects: 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.2019.113418
• Languages: English
• ISSNs: 0026-2714

Abstract

Abstract: Within this paper, we present an extensive analysis of the degradation of UV-B light-emitting diodes (LEDs) submitted to constant current stress. The study is based on combined electrical, optical and spectral characterization, and capacitance deep-level transient spectroscopy (C-DLTS). The results of this analysis demonstrate that the decrease in the optical power during the stress is stronger at low measuring current levels, indicating that the degradation is related to the increase in Shockley-Read-Hall (SRH) recombination. The electrical characterization shows a decrease in the driving voltage, probably due to an increased activation of the Mg dopant, and an increase in the sub-threshold forward current, that suggest a generation of mid-gap states during the stress. C-DLTS measurements were carried out to study the variation in defects concentration after stress; the most relevant traps were ascribed to the presence of Mg doping and/or to intrinsic defects related to the GaN growth. Highlights: Degradation consists of a decrease in optical power and an increase of sub-threshold current. Mg-related defects may play a role in the degradation. Aging induces the appearance of defects. Increased activation of Mg changes the resistivity of p-side. C-DLTS measurements confirm the presence of different type of defects.