Thermal and nonthermal factors affecting the quantum efficiency of deep-ultraviolet light-emitting diodes

✍ Scribed by Guo, H. ;Yang, Y. ;Cao, X. A.

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 349 KB
• Volume: 205
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200824046

✦ Synopsis

Abstract

The optical characteristics of AlGaN‐based multiple‐quantum‐well (MQW) light‐emitting diodes (LEDs) with peak wavelengths ranging from 265–340 nm were characterized over a wide current range. It was found that thermal effects due to self‐heating can be largely eliminated by pulsing the LEDs with a duty cycle below 0.2%. The current‐induced energy shift up to 850 A/cm^2^ was negligible in the deep‐UV LEDs, indicating the lack of localization effects. The quantum efficiency of the LEDs increased monotonically at low currents and attained a low saturated value at high currents. This is in contrast to the efficiency rolloff behavior of typical InGaN‐based LEDs resulting from carrier delocalization at high injection levels. The efficiency saturation of the deep‐UV LEDs suggests that defects play an important role in both carrier injection and recombination processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)