Atomic and Electronic Structure of the In-Bi Bilayer on the Si(111) Surface×

Recently, several 2D III-V materials, such as GaBi, InBi, TlBi, TlSb, and TlN are predicted to be topological insulators. Using the synchrotron radiation core-level photoemission spectroscopy and scanning tunneling microscopy (STM) has been utilized explore the interface and structure evolution during the sequential growth of In and Bi on the Si(111) surface by molecular beam epitaxy. Growth of 1.0-ML Bi on In/Si(111)-(4 × 1) at room temperature result in BiIn-(4 × 2), Bi_0.75In-(2 × 2) domains after post annealing below 400 °C. A phase transform to In_0.75Bi-(2 × 2) is observed following annealing at 460 °C . With reverse growth sequence, Growth of 1.0-ML In on β-Bi/Si(111)-(√3 × √3) surface following by 460 °C annealing leads to the In_0.75Bi-(2 × 2) structure. The apparent height between In_0.75Bi-(2 × 2) and β-Bi/Si(111)-(√3 × √3) is 2.0 Å, in addition, the height difference between Bi_0.75In-(2 × 2) and In/Si(111)-(4 × 1) is 2.7 Å. Scanning tunneling spectroscopy also shows that the Bi_0.75In-(2 × 2) and In_0.75Bi-(2 × 2) have different electronic properties. DFT calculation shows a small energy difference for the two structures.