Theoretical STM images of Ge monomers and trimers on Si(1 0 0)

We study, through first principles calculations based on the density functional theory, the adsorption of Ge structures on the Si(1 0 0) surface. We calculate a variety of STM images of monomers and trimers, and we show that when the monomers are isolated they can be seen in both empty and filled-state images, whereas when they are adsorbed close to other structures, as in the trimers, they are almost invisible to filled-state images.