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Microstructure investigation of semi-polar (11-22) GaN overgrown on differently designed micro-rod array templates
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Y. Gong,
R. M. Smith ,
T. Wang
Applied Physics Letters, Volume: 109, Issue: 24
Swansea University Author: Yaonan Hou
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DOI (Published version): 10.1063/1.4972403
Abstract
In order to realize semi-polar (11-22) GaN based laser diodes grown on sapphire, it is necessary to further improve the crystal quality of the (11-22) GaN obtained by using our overgrowth approach developed on regularly arrayed micro-rod templates [T. Wang, Semicond. Sci. Technol. 31, 093003 (2016)]...
| Published in: | Applied Physics Letters |
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| ISSN: | 0003-6951 1077-3118 |
| Published: |
AIP Publishing
2016
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa65304 |
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| Abstract: |
In order to realize semi-polar (11-22) GaN based laser diodes grown on sapphire, it is necessary to further improve the crystal quality of the (11-22) GaN obtained by using our overgrowth approach developed on regularly arrayed micro-rod templates [T. Wang, Semicond. Sci. Technol. 31, 093003 (2016)]. This can be achieved by carefully designing micro-rod templates. Based on transmission electron microscopy and photoluminescence measurements, it has been found that the micro-rod diameter plays a vital role in effectively reducing both the dislocation density and the basal staking fault (BSF) density of the overgrown (11-22) GaN, but in different manners. The BSF density reduces monotonically with increasing the micro-rod diameter from 2 to 5 μm, and then starts to be saturated when the micro-rod diameter further increases. In contrast, the dislocation density reduces significantly when the micro-rod diameter increases from 2 to 4 μm, and then starts to increase when the diameter further increases to 5 μm. Furthermore, employing shorter micro-rods is useful for removing additional BSFs, leading to further improvement in crystal quality. The results presented provide a very promising approach to eventually achieving (11-22) semi-polar III-nitride laser diodes. |
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| College: |
Faculty of Science and Engineering |
| Funders: |
This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) via Grant Nos. EP/M015181/1 and EP/L017024/1. |
| Issue: |
24 |