  Since the inevitability in experimental synthesis, defects show great
importance to many materials. They will deeply regulate the properties of the
materials, and then affect the further applications. Thus, exploring the
effects of defects on the properties of materials is desired. Here, by using
first-principles calculations, we systematically studied the effect of silicon
vacancy defects on the properties of silicene generated on Nterminated cubic
boron nitride (111) surface. It is found that the introduction of silicon
vacancy would trigger transition between half-metal and ferromagnetic
semiconductor. With small vacancy ratios of 1/36 and 1/24, the ground-state of
the samples would behave as ferromagnetic semiconductors, and the band gaps are
about 1.25 and 0.95 eV, respectively. When the vacancy ratio is increased up to
1/6, the sample would turn into a ferromagnetic half-metal with a half-metallic
gap of around 0.15 eV. The change of the electronic structure of the samples is
driven by the different electron transfer between silicon layer and substrate,
i.e., there will be different amount of electrons transferred from the silicon
layer to the substrate when the vacancy ratio is altered. This work would open
a new way to regulate the properties of materials and extend applications in
nanoelectronic field.
