Gas source homoepitaxy on Si(113) – the interrelation of H-induced reconstructions and growth morphology

Abstract

High-temperature, time-lapsed STM-studies are used to investigate the surface morphology and the growth mode of gas source MBE of Si on Si(113) with disilane (Si 2H 6) as a precursor. A varying hydrogen coverage on the growing surface caused by the dynamic equilibrium between hydrogen supply from the precursor and thermal H desorption at 480°C results in several different reconstructions. Phases with (2×7) and (2×5) at a low flux of disilane and a (2×2) at high flux were distinguished that consist of only two basic elements: a low-H-coverage double-row structure and the gradual insertion of high-H-coverage (2×2)-like heavy domain walls. Above H coverages resulting in the (2×5) larger domains of (2×2) separate, for which a model is suggested. Besides an anisotropic shape of the Si islands in all stages of growth, a strong influence of the H-induced reconstructions on the silicon growth mode is found. Whereas step flow dominates for the lower H-coverage structure (2×7) and (2×5), the formation of the (2×2) leads to a massive nucleation of Si islands arranged in a quasi-periodic way. This difference in nucleation behaviour results in a mechanism for a layer-by-layer-like growth mode, even on a surface with a very high hydrogen coverage in contrast to Si(111).