First-principles theory for Si-based, atomically thin layered semiconductor crystal

The authors predict, based on first principles density-functional theory total-energy calculations, that a Si-based, atomically thin layered compound (MoSi12)(n) is a semiconductor with the energy band gap being similar to 0.5 eV in the generalized gradient approximation. In this material a layer of Mo atoms is sandwiched by two layers of Si atoms in graphenelike positions with corrugations in the film-normal direction. The stability of this material arises from the Si-Si sp(3)-like covalent bonding enhanced by the corrugations and also from the Mo-Si interactions characterized by both covalent and charge-transfer natures.