Fabrication of ZnO nanorod/p-GaN high-brightness UV LED by microwave-assisted chemical bath deposition with Zn(OH)2–PVA nanocomposites as seed layer

• Published in: Optical materials 2013-03, Vol.35 (5), p.1035-1041
• Main Authors: Hassan, J.J., Mahdi, M.A., Yusof, Y., Abu-Hassan, H., Hassan, Z., Al-Attar, H.A., Monkman, A.P.
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electroluminescence; Electronics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Light emitting diode; Materials science; Nanoscale materials and structures: fabrication and characterization; Optical materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optics; Optoelectronic devices; Other luminescence and radiative recombination; Other nonlinear optical materials; photorefractive and semiconductor materials; Other topics in nanoscale materials and structures; p-GaN; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; ZnO nanorods
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2012.12.006

► We grow high quality ZnO nanorods on GaN wafer. ► We used microwave-assisted CBD to synthesis of ZnO nanorods. ► We fabricated high brightness UV LED. Chemical solution deposition is a low-temperature and possibly the lowest-cost method of growing ZnO nanorods on a GaN substrate. However, most reported methods leave an interface layer between the grown ZnO nanorods and substrate, which can interfere with light emission and extraction. Here we report the growth of high-quality, vertically aligned ZnO nanorods directly on a p-type GaN substrate, with no interface layer, by microwave-assisted chemical bath deposition using a polyvinyl alcohol (PVA)–Zn(OH)2 nanocomposites as the seed layer. X-ray diffraction and field-emission scanning electron microscopy confirmed the high quality of the nanorods in addition to the narrow and high-intensity UV peak of the photoluminescence spectrum. Three different filling insulator materials, poly methyl methacrylate (PMMA), SiO2, and PVA, were used to fabricate n-ZnO nanorod/p-GaN thin film LED structures. The electroluminescence (EL) properties for these three devices showed different emission peaks, which mainly originated from the recombination of free carriers at the two sides of the heterojunction. All devices showed excellent LED performance under forward and reverse bias; the PMMA device showed EL peaks in the UV–blue region, and the SiO2 device displayed EL peaks in the UV and green regions, respectively.