Lattice-matched heterojunctions between blue phosphorene and MXene Y2CX2 (X = F, O, and Y = Zr, Hf)

Abstract

We use ab initio calculations to explore the geometry, bonding and electronic properties of Mxene/blue phosphorene (BLP) heterobilayers. Perfect lattice-matched and energetically stable Mxene/BLP heterobilayers are firstly predicted to be vertically stacked with less than 1% lattice mismatch. The electronic properties of the heterobilayers are consistent with the substrate Mxene and the states projected on the isolated components are preserved. The unchanged electronic properties for the components upon the formation of the heterobilayers indicate the physical vdW interaction between the BLP monolayers and Mxene sheet, instead of the chemical bonds. The most stable BLP/Y2CX2 (X = O, and Y = Hf, Zr) are found to be a semiconductor with a type-II band alignment where the excited electrons and holes are localized in different layers. However, for BLP/Y2CX2 (X = F, and Y = Hf, Zr), the most stable structure is metallic with a strong band bending which lead to the existence of a partial flat band along the Γ point to the M point that mainly originates from the BLP monolayes. The appearance of the spatial separation of electron and hole and the partial flat band in these heterostructures have potential applications in optoelectronic devices and strong electron-electron correlation field. Our analysis also suggests that Mxene is a promising substrate to grow BLP monolayer epitaxially.