Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods

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Conroy, Michele
Zubialevich, Vitaly Z.
Li, Haoning
Petkov, Nikolay
Holmes, Justin D.
Parbrook, Peter J.
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Royal Society of Chemistry
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We report an inexpensive nanoscale patterning process for epitaxial lateral overgrowth (ELOG) in AlN layers grown by metal organic vapour phase epitaxy (MOVPE) on sapphire. The pattern was produced by an inductively coupled plasma etch using a self-assembled monolayer of silica spheres on AlN as the lithographic mask. The resulting uniform 1 [small mu ]m length rod structure across a wafer showed a massive reduction in threading dislocations (TDs) when annealed at 1100 [degree]C. Overgrowing homoepitaxial AlN on top of the nanorods, at a temperature of 1100 [degree]C, produced a crack free coalesced film with approximately 4 [small mu ]m of growth, which is formed at a much lower temperature compared to that typically required for microscale ELOG. The improved crystal quality, in terms of TD reduction, of the AlN above the rods was determined by detailed weak beam (WB) electron microscopy studies and showed that the threading dislocation density (TDD) was greatly reduced, by approximately two orders of magnitude in the case for edge-type dislocations. In situ reflectance measurements during the overgrowth allowed for thickness coalescence to be estimated along with wafer curvature changes. The in situ measurements also confirmed that tensile strain built up at a much slower rate in the ELOG AlN layer compared to that of AlN prepared directly on sapphire.
Epitaxial growth , Film growth , Inductively coupled plasma , Lithography , Metallorganic vapor phase epitaxy , Nanorods , Organometallics , Sapphire , Self assembled monolayers , Tensile strain , Epitaxial lateral overgrowth , In-situ measurement , Metal-organic vapour phase epitaxy , Nanoscale patterning , Orders of magnitude , Situ reflectance measurements , Threading dislocation , Threading dislocation densities , Edge dislocations
CONROY, M., ZUBIALEVICH, V. Z., LI, H., PETKOV, N., HOLMES, J. D. & PARBROOK, P. J. 2015. Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods. Journal of Materials Chemistry C, 3, 431-437. http://dx.doi.org/10.1039/C4TC01536C
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© The Royal Society of Chemistry 2015