Band alignment of Zr2CO2/MoS2 heterostructures under an electric field

Abstract

Improving the sensitivity of MoS₂-based photodetectors by constructing semiconductor heterostructures remains a challenge. To address this issue, the effects of interlayer spacing and vertical external electric fields on the interfacial interactions and electronic properties of Zr₂CO₂/MoS₂ heterostructures were investigated systematically by first-principles calculations. The results indicate that a stable interface with van der Waals interactions can form between Zr₂CO₂ and MoS₂, which complies with the type-II mechanism. By applying a vertical external electric field to the Zr₂CO₂/MoS₂ heterostructure or changing the interlayer spacing between the Zr₂CO₂ and MoS₂ monolayers, both the band gap and heterostructure type at the Zr₂CO₂/MoS₂ interface can be modulated efficiently. It is remarkable that the band alignment of the Zr₂CO₂/MoS₂ heterostructure is more sensitive to the external electric field than to the interlayer spacing. When the electric field is from −0.5 to 0.5 V Å⁻¹, the energy band of the Zr₂CO₂/MoS₂ heterostructure changes from 0.2 to 0.3 eV with a 0.1 V Å⁻¹ increase of electric field. The redistribution of charge density with the external electric field and interlayer coupling is revealed to account for the tunable energy bands. Therefore, the Zr₂CO₂/MoS₂ heterostructures with van der Waals interactions possess great potential to be used in high-performance photodetectors.