Nanofilm allotrope and phase transformation of ultrathin Bi film on Si(111)-7 × 7 were analyzed using scanning tunneling microscopy and electron diffraction experiments. It was observed that this pseudocubic {012}-oriented allotrope is stable up to four atomic layers at room temperature. The entire volume of the film started to transform into a bulk single-crystal (001) phase, as the bulk contribution in the cohesion became dominant, above the critical thickness. It was proposed that the allotrope consists of black phosphorus-like puckered layers stabilized by saturating all the pz dangling bonds in the film, based on ab initio calculations.
Nanofilm Allotrope and Phase Transformation of Ultrathin Bi Film on Si(111)7X7
SC-PR-SAITO-M-PhysRevLett_93_105501.pdf
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