Growth mechanism and microstructure of low defect density InN (0001) In-face thin films on Si (111) substrates

Transmission electron microscopy has been employed to analyze the direct nucleation and growth, by plasma-assisted molecular beam epitaxy, of high quality InN (0001) In-face thin films on (111) Si substrates. Critical steps of the heteroepitaxial growth process are InN nucleation at low substrate te...

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Bibliographic Details
Published in:Journal of applied physics 2013-10, Vol.114 (16)
Main Authors: Kehagias, Th, Dimitrakopulos, G. P., Ajagunna, A. O., Koukoula, T., Tsagaraki, K., Adikimenakis, A., Komninou, Ph, Georgakilas, A.
Format: Article
Language:English
Subjects:
Adhesive bonding
ALUMINIUM NITRIDES
DISLOCATIONS
GALLIUM NITRIDES
INDIUM NITRIDES
LAYERS
MATERIALS SCIENCE
MICROSTRUCTURE
MOLECULAR BEAM EPITAXY
NITRIDATION
NUCLEATION
ROUGHNESS
SEMICONDUCTOR MATERIALS
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
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Summary:Transmission electron microscopy has been employed to analyze the direct nucleation and growth, by plasma-assisted molecular beam epitaxy, of high quality InN (0001) In-face thin films on (111) Si substrates. Critical steps of the heteroepitaxial growth process are InN nucleation at low substrate temperature under excessively high N-flux conditions and subsequent growth of the main InN epilayer at the optimum conditions, namely, substrate temperature 400–450 °C and In/N flux ratio close to 1. InN nucleation occurs in the form of a very high density of three dimensional (3D) islands, which coalesce very fast into a low surface roughness InN film. The reduced reactivity of Si at low temperature and its fast coverage by InN limit the amount of unintentional Si nitridation by the excessively high nitrogen flux and good bonding/adhesion of the InN film directly on the Si substrate is achieved. The subsequent overgrowth of the main InN epilayer, in a layer-by-layer growth mode that enhances the lateral growth of InN, reduces significantly the crystal mosaicity and the density of threading dislocations is about an order of magnitude less compared to InN films grown using an AlN/GaN intermediate nucleation/buffer layer on Si. The InN films exhibit the In-face polarity and very smooth atomically stepped surfaces.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4827396