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On the microstructure of AlxGa1-xN layers grown on 6H-SiC(0001) substrates

Kröger, R., Einfeldt, S., Chierchia, R., Hommel, D., Reitmeier, Z.J., Davis, R.F. and Liu, Q.K.K. (2005) On the microstructure of AlxGa1-xN layers grown on 6H-SiC(0001) substrates. Journal of Applied Physics, 97 (8). Art. No. 083501. ISSN 0021-8979

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The microstructural as well as the compositional evolution of AlxGa1–xN (x~0.15) layers grown on 6H-SiC(0001) substrates by metalorganic vapor phase epitaxy were analyzed by atomic force microscopy, X-ray diffraction, and transmission electron microscopy in conjunction with energy dispersive X-ray spectroscopy. The epitaxial growth was followed from the early nucleation stage on the substrate to the development of a thick bulk-like film. Phase separation was observed during the early stage of growth; that is, islands of two different shapes formed whose Al mole fractions were about 0.035 and 0.18, respectively. The AlxGa1–xN coalesced at a film thickness of about 100 nm with the domains of varying Al content being fully coherent. Such domains were not only found at the film/substrate interface but also further away from the interface. They were arranged in layers that were shifted laterally against each other; that is, Al-deficient domains formed on top of Al-rich domains and vice versa. Increasing the film thickness to more than 100 nm finally led to a homogeneous Al distribution. Finite-element simulations were performed to calculate the strain distribution in these inhomogeneous systems. They allowed the experimental results to be explained by an interplay of strain minimization in the epitaxial film and growth kinetics.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Physics (York)
Depositing User: York RAE Import
Date Deposited: 04 Aug 2009 17:34
Last Modified: 04 Aug 2009 17:34
Published Version: http://dx.doi.org/10.1063/1.1861152
Status: Published
Publisher: American Institute of Physics
Identification Number: 10.1063/1.1861152
URI: http://eprints.whiterose.ac.uk/id/eprint/6402

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