Highly resolved non-contact atomic force microscopy images of the Sn/Si(111)-([Formula: see text]) surface

The Sn/Si(111)-([Formula: see text]) surface is observed by using non-contact atomic force microscopy (NC-AFM) at room temperature. The images at relatively far tip-surface distances show four protrusions in each ([Formula: see text]) unit cell, which are similar to previously reported scanning tunnelling microscopy (STM) images. On the other hand, it is found that, at closer tip-surface distances, eight protrusions are clearly resolved, which indicates that the spatial resolution of NC-AFM is higher than that of STM as far as imaging this surface is concerned. Our high-resolution NC-AFM images are in good agreement with a recently proposed model based on 13 Sn atoms per unit cell.