Submonolayer growth of Fe on aGaAs(100)−2×6reconstructed surface

Abstract

We present the results of in situ STM measurements of the submonolayer growth of Fe on the Ga-rich and As-terminated $(2\ifmmode\times\else\texttimes\fi{}6)$ reconstruction of the GaAs(100) surface. In the beginning of the nucleation regime (0.1 ML), the surface reconstruction influences the nucleation sites, so that almost round islands are observed solely on the top of the As rows. In the growth regime from 0.3 to 0.6 ML the islands become elliptically elongated along the [011] direction due to faster diffusion of Fe atoms along the As rows. Throughout our study, Fe atom loss is observed, becoming more pronounced from 0.6 ML onwards, due to the penetration of Fe into the substrate. This penetration leads to a trapping mechanism, which not only changes the diffusion properties of Fe clusters but also supplies extra energy to adatoms atop the Fe islands to surmount the Schwoebel barrier, resulting in a two-dimensional island nucleation from 0.3 ML onwards. A structural nucleation model is presented which provides insight into the interface structure and intermixing in the submonolayer regime.