Transition between half-metal and ferromagnetic semiconductor induced by silicon vacancy in bulk non-metallic substrate supported silicene

It should be possible to generate silicene on bulk non-metallic substrates for most applications in electronic components. However, the introduction of different types of imperfections, which significantly change the properties of materials, is inevitable in experimental synthesis. The literature on the defective silicene generated on bulk non-metallic substrates is very limited, perhaps due to the lack of experimental fabrication. Thus, by using first-principles calculations, we systematically study the effect of silicon vacancies on the properties of silicene generated on a N-terminated cubic boron nitride (111) surface. The result shows that the silicon vacancies trigger a transition between the half-metal and the ferromagnetic semiconductor. With small vacancy ratios of 1:36 and 1:24, the ground-state models behave as ferromagnetic semiconductors and the band gaps are about 1.25 and 0.95 eV, respectively. When the vacancy ratio increases up to 1:6, the model turns into a ferromagnetic half-metal with a half-metallic gap of around 0.15 eV. The change of electronic structure is driven by the different electron transfers between the silicon layer and the substrate, i.e. different amounts of electrons are transferred from the silicon layer to the substrate when the vacancy ratio is altered. Our work could extend the applications of silicene in the nanoelectronic field. (paper)