Atomistic view of the autosurfactant effect during GaN epitaxy.
The Ga-N site exchange critical to the autosurfactant effect during GaN epitaxy is studied. On the GaN(0001) pseudo (1x1), the first site exchange results in N incorporation at the subsurface T1 site, forming ghost islands. The second exchange that converts these islands to that of bilayer height can be triggered by continued scanning tunneling microscopy imaging, which involves electrons tunneling to or from localized states associated with the second layer Ga. The resulting electrostatic force sets off a chain reaction which frees these Ga atoms, allowing N to form covalent Ga-N-Ga bonds of a new GaN bilayer.
Department of Physics and Laboratory for Surface Studies, University of Wisconsin, Milwaukee, Wisconsin 53201, USA.
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