Potential energy surface of In and Ga adatoms above the (111)A and (110) surfaces of a GaAs nanopillar

Density-functional calculations of the potential-energy surface for tracer Ga and In adatoms above two GaAs (111)A and two GaAs (110) surface reconstructions are presented in order to understand the growth conditions required to form axial GaAs/InGaAs heterostructures in nanopillars. The surface reconstructions present under As-rich conditions have lower diffusion barriers for In adatoms. In addition, the binding energy of In becomes more competitive with Ga under As-rich conditions. We conclude that the As-rich reconstructions for GaAs(110) and GaAs(111)A are preferable for selective formation of heterointerfaces on (111) facets. This work helps explain the recent successful formation of axial GaAs/InGaAs heterointerfaces in catalyst free nanopillars.