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

Published online by Cambridge University Press:  15 February 2011

E. C. Piquette ,
P. M. Bridger ,
R. A. Beach  and
T. C. McGill
E. C. Piquette
Affiliation:
Thomas J. Watson, Sr. Laboratory of Applied Physics California Institute of Technology, Pasadena, CA 91125
P. M. Bridger
Affiliation:
Thomas J. Watson, Sr. Laboratory of Applied Physics California Institute of Technology, Pasadena, CA 91125
R. A. Beach
Affiliation:
Thomas J. Watson, Sr. Laboratory of Applied Physics California Institute of Technology, Pasadena, CA 91125
T. C. McGill
Affiliation:
Thomas J. Watson, Sr. Laboratory of Applied Physics California Institute of Technology, Pasadena, CA 91125
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Abstract

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 l nm RMS.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 537: Symposium G – GaN and Related Alloys , 1998 , G3.77
Copyright
Copyright © Materials Research Society 1999

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References

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