Role of island corner rounding in the morphology transition of the submonolayers grown on metal (1 1 0) surfaces

摘要

The role of island corner rounding in the temperature-dependent transition of one-dimensional (1D) monoatomic chain to two-dimensional (2D) island of the epitaixal submonolayers grown on metal (110) surfaces is studied. We show by Kinetic Monte Carlo simulations and a rate-equation analysis that for aggregation without detachment the anisotropy in corner rounding does play a decisive role in this morphology evolution, agreeing with a previous study where the one-way corner rounding controls the formation of 1D chain at intermediate temperatures and the two-way corner rounding is responsible for its transition to 2D island at high temperatures. However, for fully reversible aggregation, our simulation results reveal that the one-way corner rounding plays a minor role in the formation of 1D chain, even its activation energy can be significantly reduced. Instead, the capture of in-channel-diffusing adatoms by other adatoms or islands leading to the formation of in-channel bonds is responsible for the formation of 1D chain. With its hopping barrier normally less than that of the two-way corner rounding in metal (1 1 0) systems, the in-channel detachment by breaking one in-channel bond governs the transition of 1D chain to 2D island. Our simulation also shows that without the cross-channel atomic interaction the 2D island cannot be formed for fully reversible aggregation.