First-principles study of the contact resistance and optoelectronic properties of PdSe2/MoTe2 van der Waals heterostructure optoelectronic devices

In this study, density functional theory (DFT) calculations are carried out to investigate the contact barriers with different electrodes (Sc, Al, Ni, Pd), transport properties, and light absorption characteristics of the PdSe2/MoTe2 van der Waals (vdW) heterostructure. The lower n-type Schottky barriers of Sc-PdSe2 and Pd-MoTe2 are demonstrated. The mechanism of inter layer contact of Sc, Al-PdSe2, and Pd, Ni-MoTe2 is confirmed by the following analysis. First, the interlayer charge transfer to form an electric dipole, and the presence of an interfacial dipole, is shown to lead to changes in the metal work function and the band structure off-sets of PdSe2 , MoTe2 , thus changing the Schottky barrier height (SBH). Second, from the interfacial density of states (DOS) analysis, we demonstrate the strong hybridization of metal interface atoms with monolayer 2D material interlayer atoms, explaining the generation of gap states. In the end, the heterostructure inter-TMDs charge-transfer optical transition mechanism of the MoTe2 VBM to the PdSe2 CBM is demonstrated from the electronic structure analysis of the PdSe2/MoTe2 heterostructure. The low contact resistance and high light absorption explain the excellent performance of PdSe2/MoTe2 heterostructure optoelectronic devices. This work can provide theoretical guidance for designing next-generation electronic and optoelectronic devices.