Imaging of dimer atoms of Si(100) with the scanning tunneling microscope

Atomic structure of dimers of Si(100) has been investigated with use of scanning tunneling microscope (STM). In contrast to the usual bean-shaped image of the dimer, individual dimer atoms are clearly resolved in the occupied state images. This observation of dimer atoms cannot be explained by current dimer models and implies some effects of tip–surface interactions in STM imaging. Possible amplification mechanisms of STM corrugation by an elastic deformation of the tip or the sample are discussed.