Diffusion processes relevant to homoepitaxial growth on Ag(100)

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Abstract
We present results of theoretical calculations of activation barriers and preexponential factors for several diffusion processes that are involved in interlayer and intralayer transport on Ag(100). The thermodynamic functions necessary for the evaluation of the diffusion coefficients for adatom diffusion via hopping and exchange on a flat Ag(100) surface, and on that with a 〈110〉, and a 〈100〉 step edge, exhibit their explicit dependence on the local vibrational density of states. On the flat surface, hopping is found to be favored at low temperatures, while inclusion of bulk thermal expansion makes exchange processes competitive at higher temperatures. We show for the first time that the dominant path for interlayer transport on Ag(100) is via exchange over the 〈100〉-step edge with a negative Ehrlich-Schwoebel barrier and discuss the consequences of the relatively high barrier for adatom mobility along the 〈100〉-step edge, as compared to that along the 〈110〉.