Weak ferroelectric charge transfer in layer-asymmetric bilayers of 2D semiconductors

摘要: In bilayers of two-dimensional (2D) semiconductors with stacking arrangements which lack inversion symmetry charge transfer between the layers due to layer-asymmetric interband hybridisation can generate a potential difference layers. When analyzed using crystalline density functional theory codes, related vacuum energies above and below bilayer would contradict periodicity supercell boundary conditions. Here, we resolve this constraint by two means: (a) constructing larger supercell, including mirror reflected images separated further vacuum, (b) background dipole correction. We use both methods compare transition metal dichalcogenides (TMDs) - in particular, WSe$_2$ for find substantial stacking-dependent transfer, InSe, is found be negligibly small. The information obtained about TMDs then used map potentials generated interlayer across moir\'e superlattice twistronic bilayers.