Local cleavage of the Si(111)7x7 surface by STM

Using the scanning tunneling microscope, we report the creation of big patc hes, on a Si(111) 7 X 7 substrate, exhibiting the 2x1 reconstruction of thi s crystal. This can be done by a sudden increase of the sample bias, which produces big modifications of an initially hat area.-The inspection of thes e strongly modified areas reveals a row disposal of maxima that coincides w ith the reported topographic and spectroscopic description of the Si(III)2X 1. We propose a mechanism in which a strong removal of sample material crea tes a contact between the tip and the sample. The breaking of this contact, if crystalline, exposes a bulk termination that reconstructs with the 2X I reconstruction as it happens when cleaving silicon single crystals in the (111) orientation. [S0163-1829(99)00716-X].