Growth and coalescence in submonolayer homoepitaxy on Cu(100) studied with high-resolution low-energy electron diffraction

Abstract

By measuring the dependence of the island separation L on the flux F during submonolayer epitaxy on Cu(100), the scaling exponent p in L\ensuremath{\sim}${\mathit{F}}^{\mathrm{\ensuremath{-}}\mathit{p}/2}$ is determined in the steady-state and island coalescence regimes. In both regimes at low temperature (223 K), a crossover of p is observed from a low-flux value of 1/3 to a high-flux value of 1/2. At elevated temperatures (263--305 K), p\ensuremath{\sim}3/5 is obtained. These results agree with classic nucleation theories and recent Monte Carlo simulations, and imply that the smallest stable island changes directly to a tetramer from a low-temperature dimer with increasing temperature. Dissociation energy calculations using the embedded-atom method support these results.