STM images and energetics of the bi-covered (Ö3 × Ö3) reconstructed Si(111) surface

Bi-covered (Ö3× Ö3) reconstructed Si(111) surface has been studied by first principles calculations. Three different Bi coverages have been considered: 1 monolayer (ML), 1/3 ML and 2/3 ML, leading to the milkstool, T4 and the honeycomb structural models, respectively. Our total energy calculations show that the milkstool model is the energetically most stable structure for high Bi coverages followed by the T4 model for low Bi coverages, without going through a stable structure for the honeycomb model. We performed theoretical STM simulations...