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AuthorSun, Haiding
AuthorWu, Feng
AuthorAl tahtamouni, T M
AuthorAlfaraj, Nasir
AuthorLi, Kuang-Hui
AuthorDetchprohm, Theeradetch
AuthorDupuis, Russell D
AuthorLi, Xiaohang
Available date2020-11-19T08:53:10Z
Publication Date2017
Publication NameJournal of Physics D: Applied Physics
ResourceScopus
ISSN223727
URIhttp://dx.doi.org/10.1088/1361-6463/aa8503
URIhttp://hdl.handle.net/10576/17013
AbstractThe growth of high quality AlN epitaxial films relies on precise control of the initial growth stages. In this work, we examined the influence of the trimethylaluminum (TMAl) pretreatment of sapphire substrates on the structural properties, crystal quality and growth modes of heteroepitaxial AlN films on (0 0 0 1) sapphire substrates. Without the pretreatment, the AlN films nucleated on the smooth surface but exhibited mixed crystallographic Al- (N-) polarity, resulting in rough AlN film surfaces. With increasing the pretreatment time from 1 to 5 s, the N-polarity started to be impeded. However, small islands were formed on sapphire surface due to the decompostion of TMAl. As a result, small voids became noticeable at the nucleation layer (NL) because the growth started as quasi three-dimensional (3D) but transformed to 2D mode as the film grew thicker and got coalesced, leading to smoother and Al-polar films. On the other hand, longer pretreatment time of 40 s formed large 3D islands on sapphire, and thus initiated a 3D-growth mode of the AlN film, generating Al-polar AlN nanocolumns with different facets, which resulted into rougher film surfaces. The epitaxial growth modes and their correlation with the AlN film crystal quality under different TMAl pretreatments are also discussed.
SponsorThe KAUST authors would like to acknowledge the support of GCC Research Program REP/1/3189-01-01, Baseline BAS/1/1664-01-01, and Equipment BAS/1/1664-01-07. The work at QU was supported by GCC Research Program GCC-2017-007. The work at Georgia Institute of Technology was supported in part by DARPA under grant W911NF-15-1-0026 and NSF under grant DMR-1410874. RDD acknowledges the additional support of the Steve W Chaddick Endowed Chair in Electro-Optics and Georgia Research Alliance.
Languageen
PublisherInstitute of Physics Publishing
SubjectAlN film
crystal quality
growth mode
polarity
TMAl pretreatment
TitleStructural properties, crystal quality and growth modes of MOCVD-grown AlN with TMAl pretreatment of sapphire substrate
TypeArticle
Issue Number39
Volume Number50
dc.accessType Abstract Only


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