Published in Phys. Stat. Sol. (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
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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