Published in MRS Internet J. Nitride Semicond. Res. 5S1, W3.65 (2000).
Surface activity of magnesium during GaN molecular beam epitaxial growth
V. Ramachandran,* R. M. Feenstra,* J. E. Northrup,**
and D. W. Greve***
*Department of Physics, Carnegie Mellon University,
Pittsburgh, Pennsylvania 15213
**Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo
Alto, California 94304
***Department of Electrical and Computer Engineering, Carnegie
Mellon University,
Pittsburgh, Pennsylvania 15213
Abstract
Exposure of wurtzite GaN films grown on Si-polar 6H-SiC(0001) to
magnesium during molecular beam epitaxy (MBE) has been studied. In the
nitrogen rich regime of MBE growth, GaN films are known to grow with
rough morphology. We observe on GaN(0001) that small doses of Mg act
as a surfactant, smoothing out this roughness. An interpretation of
this surfactant behavior is given in terms of electron counting
arguments for the surface reconstructions. Previously, we have
reported that larger doses of Mg lead to inversion of the Ga-polar GaN
film to produce N-polar GaN. Several Mg-related reconstructions of the
resulting GaN(000-1) surface are reported.
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