Modifying the Band Structure of Hexagonal Boron Nitride with Metal Electrodes

Tuning the large band gap of BN to make it functional in a given device configuration has been challenging. Theoretical attempts via an external electric field, strain, and changing the interlayer distance have produced promising results, however, at unrealistically high electric field and strain values. In this DFT-based study, we propose an alternate scheme for tuning the electronic states in BN. We investigate systems in which a few layers of BN are sandwiched between two metals with different work functions, such as Cu/BN/K, creating a large electric field through the BN slab. We find that the energy gap among the BN states can be significantly decreased in such configurations. We also report on the dependence of this effect on the different metals used and the number of BN layers, as well as the BN stacking order, as the controlled growth of an alternative (Bernal) stacking order was recently reported (S. M. Gilbert et al., arXiv:1810.04814) and thus became available for such applications.