Evolution of Ge nanoislands on Si(110)-‘16 × 2’ surface under thermal annealing studied using STM

Abstract

The initial nucleation of Ge nanoclusters on Si(110) at room temperature (RT),annealing-induced surface roughening and the evolution of three-dimensional Ge nanoislandshave been investigated using scanning tunneling microscopy (STM). A few monolayers (ML) ofGe deposited at room temperature lead to the formation of Ge clusters which are homogeneouslydistributed across the surface. The stripe-like patterns, characteristic of the Si(110)-‘16 × 2’ surface reconstruction are also retained. Increasing annealing temperatures,however, lead to significant surface diffusion and thus, disruption of the underlying ‘16 × 2’ reconstruction. The annealing-induced removal of the stripe structures (originated from ‘16 × 2’ reconstruction) startsat approximately 300 °C, whereas the terrace structures of Si(110) are thermally stable up to500 °C. Atapproximately 650 °C, shallow Ge islands of pyramidal shape with(15,17,1) side facets start to form. Annealing at even higher temperatures enhances Ge islandformation. Our findings are explained in terms of partial dewetting of the metastable Gewetting layer (WL) (formed at room temperature) as well as partial relaxation of latticestrain through three-dimensional (3D) island growth.