Using first-principles calculations we show that the band gap of bilayer sheets of semiconducting transition metal dichalcogenides (TMDs) can be reduced smoothly by applying vertical compressive pressure. These materials undergo a universal reversible semiconductor to metal (S-M) transition at a critical pressure. S-M transition is attributed to lifting the degeneracy of the bands at fermi level caused by inter-layer interactions via charge transfer from metal to chalcogens. The S-M transition can be reproduced even after incorporating the band gap corrections using hybrid functionals and GW method. The ability to tune the band gap of TMDs in a controlled fashion over a wide range of energy, opens-up possibility for its usage in a range of applications.
@article{arxiv.1203.6820,
title = {Semiconductor-metal transition in semiconducting bilayer sheets of transition metal dichalcogenides},
author = {Swastibrata Bhattacharyya and Abhishek K. Singh},
journal= {arXiv preprint arXiv:1203.6820},
year = {2015}
}