The contact properties of bilayer tellurene/borophene van der Waals heterostructures with different Te orientations towards tunneling photodiode applications

Abstract The question how to modulate the contact type in bilayer (BL) tellurene-based van der Waals heterostructure (vdWH) requires to be clarified, which is the core component in optoelectronic devices, especially in photodiodes. By combining density functional theory with nonequilibrium Green’s function formalism, we built bilayer (BL) tellurene/monolayer (ML) borophene (Te/B) vdWHs with various Te orientations, in comparison with ML graphene/BL tellurene (Gr/Te). Ohmic contact is formed between BL tellurene and ML borophene, whereas Schottky contact in Gr/Te undergoes a transition from p-type to n-type by changing Te orientation from [1 0 0] to [0 0 1]. The highest tunneling barrier of 1.78 eV has endowed the strongest absorption of the infrared illumination in [1 0 0] oriented Te/B (100Te/B) vdWH. The huge lateral Schottky barrier difference between holes and electrons contributes to the reverse rectification behavior in two-probe 100Te/B vdWH with graphene contact as the left electrode under the electric field along c-direction (c-100Te/B), which could be further intensified by extending the central region and reducing the stacking region. Our work demonstrates the great potential of c-100Te/B vdWH, as an ideal p-n junction, in constructing high-performance tunneling photodiodes.