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


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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