Rotational epitaxy of a ‘soft’ metal overlayer on Si(111)

Abstract

The observation of rotational epitaxy of an incommensurate ‘soft’ Tl metal overlayer on a pseudomorphic Si(111)1×1-Tl surface by STM is reported. The structural ‘softness’ of this two-dimensional overlayer is destroyed by additional metal atom deposition, which induces condensation into three-dimensional island structures as a result of the quenching of a strain relaxation mechanism. It is suggested that the ‘soft’ Tl metal adlayer represents a meta-stage in the three-dimensional island formation process of Stranski–Krastanov growth. It is interesting that this metastable second Tl layer collapses on further growth and becomes incorporated into the three-dimensional islands once these have nucleated.