First-principles calculations of the electronic and optical properties of WSe2/Cd0.9Zn0.1Te van der Waals heterostructure

Electronic and optical properties of monolayer tungsten selenide (WSe2) and cadmium zinc telluride (Cd0.9Zn0.1Te) heterostructure with VdW, i.e., Van der Waals attractions between two layers, are explored using first-principles calculations. From the results, it is discovered that the proposed heterostructure of WSe2/Cd0.9Zn0.1Te results into nearly direct band gap semiconducting material and has staggered (Type-II) band gap alignment which is required for opto electronic applications. Moreover, the results suggest that for monolayer WSe2 and Cd0.9Zn0.1Te, optical absorption is significant in a limited range of visible spectrum (approximate to 420-470 nm) and (approximate to 390-430 nm), respectively, but more absorption takes place in the infrared (IR) region for individual layers. However, the absorption in the WSe2/Cd0.9Zn0.1Te heterostructure results in the red shift phenomenon and high absorption is achieved in the entire visible spectrum (approximate to 410-710 nm). Along with the absorption spectrum, dielectric function, refractive index and optical conductivity of the heterostructure are also calculated agreeing with the trends of each other. Desirable band alignment and high absorption coefficient in the visible spectrum can find applications in photovoltaic cells and other opto electronic devices.