Layer-by-layer versus surfactant dissolution modes in heteroepitaxy

Abstract

~Received 18 May 1999! Dissolution of a thick A film into aB substrate during metal heteroepitaxy ( A/B) obeys general trends which are described here in the case where the corresponding AB alloy presents a tendency to bulk phase separation and to B surface segregation ~e.g., A5Ni, B5Ag). Using the kinetic tight-binding Ising model, either in the mean-field or in the Monte Carlo framework, we findlayer-by-layer dissolution modes which, depending on the annealing temperature T, are preceded ( T.Tk) or not ( T,Tk) by the rising of capping B monolayers burying an almost intact A film ~surfactantlike effect!. Tk is found to decrease as the tendency to surface segregation of the substrate element increases, which can be understood in terms of local equilibrium at both the surface and the interface of the deposit. The model gives access to the main kinetic laws which are obeyed in the two dissolution modes, i.e., the total quantity of deposit matter decreases linearly with the square root of time. @S0163-1829~99!00243-X#