Monte Carlo derived diffusion parameters for Ga on the GaAs„001...-„2Ã4... surface: A molecular beam epitaxy–scanning tunneling microscopy study

The migration of individual Ga atoms on the technologically important GaAs~001!-(234) reconstructed surface has been studied as a function of substrate temperature and As4 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 mm! 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. © 2000 American Vacuum Society. @S0734-2101~00!08204-X#