Modulation of the electronic band structure of silicene by polar two-dimensional substrates

Using the density functional theory (DFT) calculations, we find that  Janus group-III chalcogenide monolayers can serve as a suitable substrate for silicene, and the Dirac electron band properties of silicene are also fully preserved. The maximum opened band gap can reach 179 meV at the Dirac point due to the interaction of silicene and the polar two-dimensional (2D) substrate. In addition, the electronic band structure of the heterostructure can be modulated by applying an electric field where its predicted band gap increases or decreases according to the direction of the applied external electric field. Furthermore, an insight into the electron structures can be understood by analyzing the electron energy-loss (EEL) spectra. From these results, we also predict that heterostructures with polar 2D substrates have broad application prospects in multi-functional devices. Besides, Janus group-III chalcogenide monolayers can be used as good substrates for growing silicene and the modulation of the electronic structure can also be applied to nanodevices and optoelectronic devices.