Tunable electronic and optical properties of GaS/GaSe van der Waals heterostructure

We have used first-principles calculations to investigate the electronic and optical properties of GaS/GaSe van der Waals heterostructures formed by stacking two-dimensional GaSe and GaSe monolayers. Our findings confirm that the GaS/GaSe heterostructures transform from an indirect to a direct band gap material for the two stackings considered in this study. In addition, we found that the direct band gaps are 1.780 eV and 1.736 eV for AA and AB stacking, respectively. It is observed that the behavior of the optical properties of AA stacking is similar to AB stacking with some differences in details and both heterostructures located in UV range. The refractive index values are 2.21 (AA pattern) and 2.18 (AB pattern) at zero photon energy limit and increase to 2.937 for AA and 2.18 AB patterns and both located in the visible region. More importantly, the GaS/GaSe heterostructures have a variety of extraordinary electronic and optical properties. Accordingly, these heterostructures can be useful for the solar cell, nanoelectronics, and optoelectronic applications.