Performance of Flip-Chip Thin-Film GaN Light-Emitting Diodes With and Without Patterned Sapphires

• Published in: IEEE photonics technology letters Vol. 22; no. 8; pp. 550 - 552
• Main Authors: Horng, R.-H., Hung-Lieh Hu, Mu-Tao Chu, Yu-Li Tsai, Yao-Jun Tsai, Chen-Peng Hsu, Dong-Sing Wuu
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.04.2010; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Conferences; Devices; Fiber optics; Flip-chip (FC); Gallium nitride; Gallium nitrides; Light emitting diodes; Optical fibers; Optical reflection; patterned sapphire substrate (PSS); Rough surfaces; Roughening; Sapphire; Substrates; Surface morphology; Surface roughness; Thermal conductivity; Thin film devices; thin-film technique; Transistors
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2010.2042590

We report on improved device performance of flip-chip (FC) GaN-based light-emitting diodes (LEDs) by combining patterned sapphire substrate (PSS) and thin-film techniques. It was found that an FC LED grown on a conventional planar sapphire exhibits a power enhancement factor of only 36.3% after the thin-film processes of substrate removal and surface roughening. In contrast, the as-fabricated FC LED grown on a PSS showed a power enhancement factor of up to 62.3% without any postprocess as compared with the light output power of an original conventional FC LED. Further intensity improvement to 74.4% could be achieved for the FC LED/PSS sample with the thin-film processes.