Observation of Initial Growth of In on Silicon(100) Surface

The initial growth of In on a Si(100) surface as a function of the coverage has been investigated using scanning tunneling microscopy (STM). In(2×2) is a frequently observed phase at coverages below 0.5 monolayer (ML), the In(2×1) phase appears at the coverage above 0.5 ML, and the coexistence of the In(2×2) and In(2×1) reconstructions becomes a dominant phase at the coverage between 0.5 ML and 1.0 ML. Further deposition of In above 1.0 ML gives rise to the onset of three-dimensional island nucleation and growth associated with layer-by-layer growth. The island is highly oriented with major axes along the <011> directions. The island is located on the terrace adjacent to the step edge, suggesting that the step edge should be a preferred site for island nucleation.