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AuthorSun, Haiding
AuthorWu, Feng
AuthorPark, Young Jae
AuthorAl tahtamouni, T. M.
AuthorLi, Kuang-Hui
AuthorAlfaraj, Nasir
AuthorDetchprohm, Theeradetch
AuthorDupuis, Russell D.
AuthorLi, Xiaohang
Available date2020-09-24T10:49:24Z
Publication Date2017
Publication NameApplied Physics Letters
ResourceScopus
URIhttp://dx.doi.org/10.1063/1.4983388
URIhttp://hdl.handle.net/10576/16301
AbstractThe trimethylaluminum (TMAl) preflow process has been widely applied on sapphire substrates prior to growing Al-polar AlN films by metalorganic chemical vapor deposition. However, it has been unclear how the TMAl preflow process really works. In this letter, we reported on carbon's significance in the polarity and growth mode of AlN films due to the TMAl preflow. Without the preflow, no trace of carbon was found at the AlN/sapphire interface and the films possessed mixed Al- and N-polarity. With the 5 s preflow, carbon started to precipitate due to the decomposition of TMAl, forming scattered carbon-rich clusters which were graphitic carbon. It was discovered that the carbon attracted surrounding oxygen impurity atoms and consequently suppressed the formation of AlxOyNz and thus N-polarity. With the 40 s preflow, the significant presence of carbon clusters at the AlN/sapphire interface was observed. While still attracting oxygen and preventing the N-polarity, the carbon clusters served as randomly distributed masks to further induce a 3D growth mode for the AlN growth. The corresponding epitaxial growth mode change is discussed.
SponsorNational Science Foundation,NSF: DMR-1410874, Defense Advanced Research Projects Agency, DARPA: W911NF-15-1-0026
Languageen
PublisherAmerican Institute of Physics Inc.
SubjectTMAl
AlN
TitleInfluence of TMAl preflow on AlN epitaxy on sapphire
TypeArticle
Issue Number19
Volume Number110
dc.accessType Abstract Only


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