Li, Z, Jiu, L, Gong, Y. et al. (4 more authors) (2017) Semi-polar (11-22) AlGaN on overgrown GaN on micro-rod templates: Simultaneous management of crystal quality improvement and cracking issue. Applied Physics Letters, 110 (8). ISSN 0003-6951
Abstract
© 2017 Author(s).Thick and crack-free semi-polar (11-22) AlGaN layers with various high Al compositions have been achieved by means of growth on the top of nearly but not yet fully coalesced GaN overgrown on micro-rod templates. The range of the Al composition of up to 55.7% was achieved, corresponding to an emission wavelength of up to 270 nm characterised by photoluminescence at room temperature. X-ray diffraction (XRD) measurements show greatly improved crystal quality as a result of lateral overgrowth compared to the AlGaN counterparts on standard planar substrates. The full width at half maximums of the XRD rocking curves measured along the [1-100]/[11-2-3] directions (the two typical orientations for characterizing the crystal quality of (11-22) AlGaN) are 0.2923°/0.2006° for 37.8% Al and 0.3825°/0.2064° for 55.7% Al, respectively, which have never been achieved previously. Our calculation based on reciprocal space mapping measurements has demonstrated significant strain relaxation in the AlGaN as a result of utilising the non-coalesced GaN underneath, contributing to the elimination of any cracks. The results presented have demonstrated that our overgrowth technique can effectively manage strain and improve crystal quality simultaneously.
Metadata
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Copyright, Publisher and Additional Information: | © 2017 Author(s). This is an author produced version of a paper subsequently published in Applied Physics Letters. Uploaded in accordance with the publisher's self-archiving policy. | ||||||
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Institution: | The University of Sheffield | ||||||
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Electronic and Electrical Engineering (Sheffield) | ||||||
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Depositing User: | Symplectic Sheffield | ||||||
Date Deposited: | 15 Mar 2017 11:02 | ||||||
Last Modified: | 07 Nov 2017 15:21 | ||||||
Published Version: | https://doi.org/10.1063/1.4977094 | ||||||
Status: | Published | ||||||
Publisher: | AIP Publishing | ||||||
Refereed: | Yes | ||||||
Identification Number: | https://doi.org/10.1063/1.4977094 |