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Effect of Buffer Layer and III/V Ratio on the Surface Morphology of GaN Grown by MBE

Piquette, E. C. and Bridger, P. M. and Beach, R. A. and McGill, T. C. (1999) Effect of Buffer Layer and III/V Ratio on the Surface Morphology of GaN Grown by MBE. MRS Internet Journal of Nitride Semiconductor Research, 4S1 . Art. No. G3.77. ISSN 1092-5783.

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The surface morphology of GaN is observed by atomic force microscopy for growth on GaN and AlN buffer layers and as a function of III/V flux ratio. Films are grown on sapphire substrates by molecular beam epitaxy using a radio frequency nitrogen plasma source. Growth using GaN buffer layers leads to N-polar films, with surfaces strongly dependent on the flux conditions used. Flat surfaces can be obtained by growing as Ga-rich as possible, although Ga droplets tend to form. Ga-polar films can be grown on AlN buffer layers, with the surface morphology determined by the conditions of buffer layer deposition as well as the III/V ratio for growth of the GaN layer. Near-stoichiometric buffer layer growth conditions appear to support the flattest surfaces in this case. Three defect types are typically observed in GaN films on AlN buffers, including large and small pits and "loop" defects. It is possible to produce surfaces free from large pit defects by growing thicker films under more Ga-rich conditions. In such cases the surface roughness can be reduced to less than 1 nm RMS.

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Additional Information:© 1999 The Materials Research Society. This work was supported by the Defense Advanced Research Projects Agency and the Electric Power Research Institute under contract number MDA972-98-1-0005. This article was presented as part of Symposium G, "Gallium Nitride and Related Alloys" at the 1998 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 30-December 4.
Record Number:CaltechAUTHORS:PIQmrsijsnr99
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Official Citation:MRS Internet J. Nitride Semicond. Res. 4S1, G3.77 (1999).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9316
Deposited By: Archive Administrator
Deposited On:12 Dec 2007
Last Modified:02 Oct 2019 23:59

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