Epitaxial Growth and Electronic structure measurement of a New Two-Dimensional Binary Alloy with Honeycomb Lattice: Sn₂Bi

After the discovery of graphene and it’s exotic physical properties such as Dirac cones in electronic structures due to specific honeycomb lattice, several new mono-elemental 2D materials with honeycomb lattice such as silicene, germanene, stanene, borophene, antimonene have been realized. Most of these 2D materials are grown on metal substrates which limits further studies of transport and applications. In this work, we successfully grow a new novel 2D binary alloy Sn2Bi on Si(111) surface. As the most famous semiconductor, using Silicon as substrate can both meet the requirements of intrinsic property preservation and transport measurement. Also Si(111) surface has the same symmetry (C_3v) with honey comb lattice. Combined with STM and DFT calculations, we confirm a honeycomb lattice in this 2D alloy with one hexagonal ring consisting two Bi and four Sn atoms. The STS measurements reveal a 0.8 eV gap and near-free electronic states on this 2D alloy, which are further reproduced by ARPES and tr-ARPES measurements and DFT calculations.