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Self-assembled indium tin oxide nanoball-embedded omnidirectional reflectors for high photon extraction efficiency in III-nitride ultraviolet emitters

Abstract

The control of refractive index and electrical conductivity in dielectric layer of onmidirectional reflectors (ODRs) is essential to improve the low efficiency of AlGaN-based UV emitters. Here, we report self-assembled indium tin oxide (ITO) nanoball-embedded omnidirectional reflectors (NODRs) for use in high-efficiency AlGaN-based UV emitters of 365 nm. This NODRs consisted of a reflective Al layer, self-assembled conducting ITO nanoball layer for current injection and spreading, and nanovoids that provided a low refractive index to achieve a highly efficient UV emitters. The NODR was able to realize both high electrical conductivity and reflectivity by decreasing the average refractive index of the ITO nanoball layers. We observed diffuse reflection as well as omnidirectional reflection from the NODR UV emitters because of the corrugated interfaces of the nanovoids, ITO nanoball layer, and Al layer. These structural and optical properties of the NODRs remarkably increased the output power of a UV emitter by a Lambertian enhancement factor of 57% at an injection current of 50 mA at all emission angles compared with that of an ITO film/Al UV emitter.

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Publication details

The article was received on 09 Feb 2017, accepted on 28 Apr 2017 and first published on 03 May 2017


Article type: Paper
DOI: 10.1039/C7NR00957G
Citation: Nanoscale, 2017, Accepted Manuscript
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    Self-assembled indium tin oxide nanoball-embedded omnidirectional reflectors for high photon extraction efficiency in III-nitride ultraviolet emitters

    S. Oh, K. J. Lee, S. Kim, K. Ha, J. Jeong, D. Kim, K. Kim and S. Park, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR00957G

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