Extended α-phase Bi atomic layer on Si(1 1 1) fabricated by thermal desorption

Abstract

Two-dimensional materials with sizable spin-orbit coupling are not only interesting to fundamental studies, but also useful candidates for technological applications. Here, we report on the fabrication of extended α-phase Bi atomic layer on Si(1 1 1) surface by means of thermal desorption. The atomic and electronic structures have been investigated by combining scanning tunneling microscopy (STM) experiments with density functional theory (DFT) calculations. While β-phase Bi trimer with 3×3R30° surface reconstruction can be prepared by room-temperature deposition with subsequent post annealing at 700 K, the α-phase Bi monomer only appears at 800 K due to thermal desorption with the Bi desorption rate of 0.26 ML/min. From our DFT calculations, the α-phase Bi shows Rashba energies ER = 15 meV and 3 meV at high symmetry points of M¯ and K¯, respectively. Since α-phase Bi monomer represents isotropic lattice symmetry with a dilute Bi density, it may serve as a potential template to tune Rashba effect by incorporating with multiple elements.