Electron regulation and gas-sensitivity analysis of hBN-Graphene lateral heterojunctions--First principle study

Abstract

In this paper, the first-principle calculations of the lateral heterojunction model synthesized by hBN-Graphene were carried out, and it was found that the bandgap of graphene varied with the change in the proportion of hBN, and the bandgap was best regulated with a bandgap of 1.177 eV when the proportion of hBN was 66.67 %. At this time, the adsorption structures of HCN, CO, NH3, and Cl₂ were established and energy band calculations were performed on the hBN and Graphene portions of the hBN-Graphene lateral heterojunctions, respectively, and it was found that the adsorption of Cl₂ resulted in a significant change in the band gap, which showed a very high electrical sensitivity. To further investigate the adsorption mechanism of Cl₂ on the surface of hBN-Graphene lateral heterojunction, the energy band structure, PDOS, charge transfer, adsorption energy, and recovery time of each stabilized adsorption site of Cl₂ on the surface of hBN-Graphene lateral heterojunction were calculated. The results show that the adsorption of Cl₂ on the surface of hBN-Graphene lateral heterojunction is a stable chemisorption, and the band gap of C-Top1 increases to 1.274 eV, and the band gaps of C-Top3, N-Top1, and N-Top2 decrease to 0.684 eV, 0.376 eV, and 0.398 eV, respectively, and the changes of band gaps are significant and easy to be electrically detection. The recovery time of Cl₂ on the surface of hBN-Graphene lateral heterojunction was 7.36 s-2.59 s in visible light and in the temperature interval of 273 K-283 K. The recovery time of Cl₂ on the surface of hBN-Graphene lateral heterojunction was 7.36 s-2.59 s in visible light and in the temperature interval of 273 K-283 K. These findings have implications for the research and application of graphene-based Cl₂ gas sensors.

Keywords: Gas sensitivity; Graphene; Hexagonal boron nitride; The first principle; The lateral heterojunctions.