  Silicene is a promising 2D Dirac material as a building block for van der
Waals heterostructures (vdWHs). Here we investigate the electronic properties
of hexagonal boron nitride/silicene (BN/Si) vdWHs using first-principles
calculations. We calculate the energy band structures of BN/Si/BN
heterostructures with different rotation angles and find that the electronic
properties of silicene are retained and protected robustly by the BN layers. In
BN/Si/BN/Si/BN heterostructure, we find that the band structure near the Fermi
energy is sensitive to the stacking configurations of the silicene layers due
to interlayer coupling. The coupling is reduced by increasing the number of BN
layers between the silicene layers and becomes negligible in BN/Si/(BN)3/Si/BN.
In (BN)n/Si superlattices, the band structure undergoes a conversion from Dirac
lines to Dirac points by increasing the number of BN layers between the
silicene layers. Calculations of silicene sandwiched by other 2D materials
reveal that silicene sandwiched by low-carbon-doped boron nitride or HfO2 is
semiconducting.
