Low-temperature atomic assembly of stoichiometric gallium arsenide from equiatomic vapor

The low-temperature atomic assembly of homoepitaxial GaAs thin films on the (001) surface has been investigated using molecular dynamics with a Stillinger-Weber potential energy function. During equiatomic vapor deposition, crystalline growth was observed for substrate temperatures above 35% of the melting temperature. Below this temperature, the critical epitaxial thickness began to rapidly decrease as defects were increasingly incorporated and eventually nucleated an entirely amorphous structure. The atomic assembly mechanisms of arsenic dimer incorporation, as well as gallium vacancy formation, were studied just above the amorphous/crystalline growth transition temperature. The adsorption of arsenic dimers was found to show dependence upon the orientation of the deposited molecule. Atomic processes responsible for the formation of the gallium vacancy defects were observed, and the influence of growth temperature on defect formation was also identified. (c) 2005 Elsevier B.V. All rights reserved.