Realization of controllable multifunctionality by interfacial engineering: The case of silicene/hBN van der Waals heterostructure

The study demonstrates layer-sliding-mediated controlled interfacial engineering to induce multifunctionality into a van der Waals heterostructure (vdWHS), consisting of two-dimensional (2D) silicene and hexagonal boron nitride (hBN). To manifest the aforementioned strategy, silicene is slided over hBN, and the resulting variations in the physical properties such as interfacial electronic and optical properties of vdWHS are analyzed. A nifty modeling of vdWHS, not only identifies the most stable stacking pattern but also minimizes the lattice mismatch between silicene and hBN to 2.97%. After obtaining the most optimal stacking configuration of vdWHS, the position of potassium (K) intercalant at the interface is screened out. Various physical parameters such as binding energy, vdW-gap and buckling distance (ΔZ) relating to the intercalated system are computed repeatedly along the sliding pathway. The stability of the various K-intercalated stacking patterns is verified by calculating and comparing the total energies with and without vdW contributions. Upon completion of the sliding, calculated vdW-gap with and without vdW contributions increases by 2.7 and 5.6%, respectively. The highest energy barrier encountered throughout the sliding pathway with (without) vdW contributions is 0.84 (0.72) eV. Planar average charge density difference, charge transfer, and interface dipole moment are calculated and analyzed to investigate the variation in interfacial electronic properties resulting from layer-sliding and intercalation. A notable increase (5.86%) in charge transfer from hBN to silicene is seen upon completion of the layer-sliding. Several optical properties associated with the intercalated vdWHS such as real [\varepsilon_1\left(\omega\right)] and imaginary [\varepsilon_2\left(\omega\right)] parts of the complex dielectric function (DF), electron energy loss function [L\left(\omega\right)], diagonal components of the dielectric tensor [\varepsilon\left(i\omega\right)] and optical joint density of states\ \left[J\left(\omega\right)\right] have been examined. Polarizability of un-slided vdWHS is changed significantly due to the layer-sliding, with a reduction of 24.85 and 6.76% for the midway and fully-slided configurations, respectively. Sliding process results in an increase in the optical absorption in the UV region by 23.14 and 44.18% for the midway and fully-slided configurations as compared with the un-slided vdWHS. Plots relating to J\left(\omega\right)\ indicate that the most probable optical transitions occur at 7.50, 7.66, and 7.43 eV for the initial, middle, and fully-slided configurations, respectively. The suggested layer-sliding technique has a potential to introduce multifunctionality in 2D materials by varying the properties in a controllable and reversible manner.