Improvement of crystal quality and optical property in (11−22) semipolar InGaN/GaN LEDs grown on patterned m-plane sapphire substrate

• Published in: Journal of crystal growth 2012-12, Vol.361, p.166-170
• Main Authors: Jang, Jongjin, Lee, Kwanhyun, Hwang, Junghwan, Jung, Joocheol, Lee, Seunga, Lee, Kyuho, Kong, Bohyun, Cho, Hyunghoun, Nam, Okhyun
• Format: Article
• Language: English
• Subjects: A3. Metalorganic chemical vapor deposition; Applied sciences; B1. GaN; B1. Patterned sapphire substrate; B3. Light emitting diode; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density; Electronics; Exact sciences and technology; Extraction; Gallium nitrides; Indium gallium nitrides; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Optoelectronic devices; Physics; Reduction; Roughness; Sapphire; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Stacking faults; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.08.052

Semipolar GaN layers were grown on the m-plane hemispherical patterned sapphire substrates (HPSS) using metal organic chemical vapor deposition in order to reduce the defect density and enhance the extraction efficiency of light. The roughness values of the GaN surface grown on the planar sapphire and the HPSS were 30 and 23nm root-mean-square roughness for a 20×20-μm2 area, respectively. The reduction of basal stacking fault density was demonstrated by x-ray rocking curve of off-axis planes and cross-sectional transmission electron microscopy. The low-temperature photoluminescence measurement showed that the near band-edge emission from HPSS semipolar GaN was approximately one order of magnitude stronger than that from planar semipolar GaN layer. The InGaN light emitting diode grown on the HPSS showed an output power approximately 1.5 times that on the planar m-sapphire. ► Semipolar GaN layer on the HPSS showed was grown to be a pit-free and mirror-like surface. ► On-axis and off-axis XRD measurement and cross-sectional TEM results confirm that the HPSS has efficiently reduced the BSFs. ► Semipolar LED on the HPSS shows about 1.5 times higher output power than does the planar LED.