Improvement in the characteristics of GaN-based light-emitting diodes by inserting AlGaN-GaN short-period superlattices in GaN underlayers

• Published in: IEEE photonics technology letters 2006-07, Vol.18 (14), p.1497-1499
• Main Authors: Wang, Cheng-Liang, Gong, Jyh-Rong, Yeh, Ming-Fa, Wu, Bor-Jen, Liao, Wei-Tsai, Lin, Tai-Yuan, Lin, Chung-Kwei
• Format: Article
• Language: English
• Subjects: Counting; Current measurement; Diffraction; Etching; Gallium nitride; Gallium nitrides; GaN; Light emitting diodes; light-emitting diode (LED); Liquid crystal displays; Optical films; Semiconductor films; short-period superlattice (SPSL); Superlattices; Threading dislocations; Transmission electron microscopy; X-ray diffraction; X-rays
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2006.877587

We report the influence of short-period superlattice (SPSL)-inserted structures in the underlying undoped GaN on the characteristics of GaN-based light-emitting diodes (LEDs). The measurements of current-voltage (I-V) curves indicate that GaN-based LEDs having pseudomorphic Al/sub 0.3/Ga/sub 0.7/N(2 nm)-GaN(2 nm) SPSL-inserted structures exhibit improvements in device characteristics with the best LED being inserted with two sets of five-pair Al/sub 0.3/Ga/sub 0.7/N(2 nm)-GaN(2 nm) SPSL structure. Based upon the results of etch pit counts, double-crystal X-ray diffraction measurements and transmission electron microscopic observations of the GaN-based LEDs, it was found that the Al/sub 0.3/Ga/sub 0.7/N(2 nm)-GaN(2 nm) SPSL-inserted structures tended to serve as threading dislocation filters in the LEDs so that the improved I-V characteristics were achieved.