Published in Physica Status Solidi (c) 2, 2183 (2005).
Effects of Hydrogen during Molecular Beam Epitaxy of GaN
Y. Dong and R. M. Feenstra
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
Abstract
We study the effect of introducing hydrogen gas through the RF plasma source during
plasma-assisted molecular beam epitaxy of GaN(0001). The well-known smooth-to-rough
transition that occurs for this surface as a function of decreasing Ga flux in the
absence of H is found to persist even with H present. But, the critical Ga flux for
this transition is increased by the presence of H, and for sufficiently high H pressure
a new 2 × 2 surface structure that is believed to be H-terminated is observed. Under
Ga-rich conditions, the presence of hydrogen is found to induce step bunching on the surface,
from which we argue that H selectively bonds to surface step and/or kink sites.
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