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Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56

Pushing the emission wavelength of efficient ultraviolet (UV) emitters further into the deep-UV requires material with high crystal quality, while also reducing the detrimental effects of built-in electric fields. Crack-free semi-polar [Formula: see text] Al(x)Ga(1−x)N epilayers with AlN contents up...

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Autores principales: Bruckbauer, Jochen, Li, Zhi, Naresh-Kumar, G., Warzecha, Monika, Edwards, Paul R., Jiu, Ling, Gong, Yipin, Bai, Jie, Wang, Tao, Trager-Cowan, Carol, Martin, Robert W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5589948/
https://www.ncbi.nlm.nih.gov/pubmed/28883495
http://dx.doi.org/10.1038/s41598-017-10923-9
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author Bruckbauer, Jochen
Li, Zhi
Naresh-Kumar, G.
Warzecha, Monika
Edwards, Paul R.
Jiu, Ling
Gong, Yipin
Bai, Jie
Wang, Tao
Trager-Cowan, Carol
Martin, Robert W.
author_facet Bruckbauer, Jochen
Li, Zhi
Naresh-Kumar, G.
Warzecha, Monika
Edwards, Paul R.
Jiu, Ling
Gong, Yipin
Bai, Jie
Wang, Tao
Trager-Cowan, Carol
Martin, Robert W.
author_sort Bruckbauer, Jochen
collection PubMed
description Pushing the emission wavelength of efficient ultraviolet (UV) emitters further into the deep-UV requires material with high crystal quality, while also reducing the detrimental effects of built-in electric fields. Crack-free semi-polar [Formula: see text] Al(x)Ga(1−x)N epilayers with AlN contents up to x = 0.56 and high crystal quality were achieved using an overgrowth method employing GaN microrods on m-sapphire. Two dominant emission peaks were identified using cathodoluminescence hyperspectral imaging. The longer wavelength peak originates near and around chevron-shaped features, whose density is greatly increased for higher contents. The emission from the majority of the surface is dominated by the shorter wavelength peak, influenced by the presence of basal-plane stacking faults (BSFs). Due to the overgrowth technique BSFs are bunched up in parallel stripes where the lower wavelength peak is broadened and hence appears slightly redshifted compared with the higher quality regions in-between. Additionally, the density of threading dislocations in these region is one order of magnitude lower compared with areas affected by BSFs as ascertained by electron channelling contrast imaging. Overall, the luminescence properties of semi-polar AlGaN epilayers are strongly influenced by the overgrowth method, which shows that reducing the density of extended defects improves the optical performance of high AlN content AlGaN structures.
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spelling pubmed-55899482017-09-13 Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56 Bruckbauer, Jochen Li, Zhi Naresh-Kumar, G. Warzecha, Monika Edwards, Paul R. Jiu, Ling Gong, Yipin Bai, Jie Wang, Tao Trager-Cowan, Carol Martin, Robert W. Sci Rep Article Pushing the emission wavelength of efficient ultraviolet (UV) emitters further into the deep-UV requires material with high crystal quality, while also reducing the detrimental effects of built-in electric fields. Crack-free semi-polar [Formula: see text] Al(x)Ga(1−x)N epilayers with AlN contents up to x = 0.56 and high crystal quality were achieved using an overgrowth method employing GaN microrods on m-sapphire. Two dominant emission peaks were identified using cathodoluminescence hyperspectral imaging. The longer wavelength peak originates near and around chevron-shaped features, whose density is greatly increased for higher contents. The emission from the majority of the surface is dominated by the shorter wavelength peak, influenced by the presence of basal-plane stacking faults (BSFs). Due to the overgrowth technique BSFs are bunched up in parallel stripes where the lower wavelength peak is broadened and hence appears slightly redshifted compared with the higher quality regions in-between. Additionally, the density of threading dislocations in these region is one order of magnitude lower compared with areas affected by BSFs as ascertained by electron channelling contrast imaging. Overall, the luminescence properties of semi-polar AlGaN epilayers are strongly influenced by the overgrowth method, which shows that reducing the density of extended defects improves the optical performance of high AlN content AlGaN structures. Nature Publishing Group UK 2017-09-07 /pmc/articles/PMC5589948/ /pubmed/28883495 http://dx.doi.org/10.1038/s41598-017-10923-9 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Bruckbauer, Jochen
Li, Zhi
Naresh-Kumar, G.
Warzecha, Monika
Edwards, Paul R.
Jiu, Ling
Gong, Yipin
Bai, Jie
Wang, Tao
Trager-Cowan, Carol
Martin, Robert W.
Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56
title Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56
title_full Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56
title_fullStr Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56
title_full_unstemmed Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56
title_short Spatially-resolved optical and structural properties of semi-polar [Formula: see text] Al(x)Ga(1−x)N with x up to 0.56
title_sort spatially-resolved optical and structural properties of semi-polar [formula: see text] al(x)ga(1−x)n with x up to 0.56
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5589948/
https://www.ncbi.nlm.nih.gov/pubmed/28883495
http://dx.doi.org/10.1038/s41598-017-10923-9
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