Si(111) islands on β-phase Si(111)√3 × √3R30°-Bi

Beta-phase root 3 x root 3R30 degrees-bismuth (Bi) on silicon (Si)(111)7 x 7 surface has been exploited as a template for growing Si films. Two-dimensional Si islands with root 3 x root 3 reconstruction, parallel to that of Si(111)root 3 x root 3R30 degrees-Bi, have been resolved by means of scanning tunneling microscopy, grazing-incidence X-ray diffraction (XRD) and low electron energy diffraction. Auger electron spectroscopy and scanning tunneling spectroscopy gave interesting electronic features on two-dimensional Si islands, with the evidence of a reduced band gap to similar to 0.55 eV, related to the presence of the underneath Bi layer, and atomic structural properties typical of Si(111). These experimental findings fully confirm the recently reported calculation based on the first-principles density functional theory, on the prediction of Si(111) growth on top of beta-phase root 3 x root 3R30 degrees-Bi/Si(111)7 x 7 reconstruction, shedding new light on silicon structures.