Effect of strain and external electric field on the optoelectronic properties of HfS2/ZrSe2 heterostructures

Abstract

The strain’s electrical structure and optical characteristics as well as the electric field acting HfS₂/ZrSe₂ heterojunction structure have been calculated by a first-principles approach based on density functional theory. A strain of −6%-6% is applied to the HfS₂/ZrSe₂ heterojunction to analyze the changes in energy bands, density of states, dielectric function, and absorption coefficient. An electric field was also applied to the HfS₂/ZrSe₂ heterojunction structure in the range of ± 0.08 V/Å with the increment set to 0.02 V/Å to analyze the electronic structure and optical properties. It is found that the heterojunction structure has an increasing gap when subjected to tension and a decreasing band gap under compressive strain. When the compressive strain exceeds −4%, the heterojunction structure is transformed from semiconductor to metal, and the electrical conductivity is greatly improved; the highest absorption coefficient and the most obvious changes are observed when compressed to −6%; the direct band gap is always maintained under the action of the electric field which is beneficial to the material’s use of light. A decrease in the band gap under the action of a positive electric field makes it easier for electrons to jump and promotes charge transfer.