Monte Carlo derived diffusion parameters for Ga on the GaAs(001)-(2x4) surface: A molecular beam epitaxy-scanning tunneling microscopy study

The migration of individual Ga atoms on the technologically important GaAs(001)-(2 X 4) reconstructed surface has been studied as a function of substrate temperature and As-4 pressure using a combined molecular beam epitaxy and scanning tunneling microscope ultrahigh vacuum multichamber facility. We have deposited 10% of a plane of Ga onto a GaAs(001) surface with a low defect density (<1%) and with large terraces (>0.5 mu m) to avoid the influence of surface defects like step edges and vacancies. Both the island number density and the geometry are measured and compared to Monte Carlo solid-on-solid simulations. Basic diffusion parameters, such as the activation energy, directional hopping-rate ratio, directional sticking-probability ratio, etc., are reported. (C) 2000 American Vacuum Society. [S0734-2101(00)08204-X].