First-principles determination of electronic properties of MoSe2/HfSe2 and MoSe2/HfSe2/MoSe2 vdW heterostructures on mica with spin-orbit coupling

In this study, Density functional theory (DFT) calculations were conducted to calculate the structural, electronic, transport, and optical properties of MoSe2 and HfSe2 monolayers (MLs) and the proposed modelled interfaces of MoSe2/HfSe2 and MoSe2/HfSe2/MoSe2 on mica substrate. According to atomistic calculations, in MoSe2/HfSe2/ mica, the mica substrate acts as the important source of excess charge that dopes the adjacent 2D TMDs layers, while by adding another layer of MoSe2 to the interface, the HOMO and LUMO states showed more charge delocalization between MoSe2 and HFSe2 MLs. The Band structure calculation reveal that the indirect band gaps with spin-orbit coupling (SOC) calculations have estimated to be 0.43 eV /0.31 eV and 0.37 eV/0.24 eV from K→K/Γ→K for MoSe2/HfSe2 and MoSe2/HfSe2/MoSe2 van der Waals (vdW) heterostructures, respectively, lower than the band gaps of MoSe2 (1.44 eV)/HFSe2 (1.20 eV) nanosheets. Mulliken charge analysis indicated how presence the MoSe2 monolayer able to influence Se atoms in centre of the MoSe2/HfSe2/MoSe2 to receive the charge, while in MoSe2/HfSe2 those situated in the side of MoSe2 participated in the charge transfer more. Our results point to the phonon-limited mobility of 52.1 cm2 V− 1 s − 1 with a carrier density of 2.91 × 1012 cm3 for MoSe2/HfSe2/MoSe2 interface, which is higher than that of HfSe2 but lower compared to what was previously found for the MoSe2 monolayer. We have also computed a very low lattice thermal conductivity of 0.58 Js− 1 m− 1 K− 1 for the MoSe2/HfSe2/MoSe2 heterostructure is mainly provided by an in-plane (yy) tensor with a value of 0.401 Js− 1 m− 1 K− 1 . Moreover, the optical properties showed a remarkable improvement in the absorption coefficient of vdW heterostructures than MLs with the first adsorption peaks at 12 THz and 36 THz. The DFT outcomes revealed how adding the second layer of MoSe2 in MoSe2/HfSe2/MoSe2 can change the adsorption intensity and dielectric constant along the different in-plane directions as well as interlayer coupling.