A Study On Gas-Sensitive Mechanism Of Al And P Doped Silicene Materials

Silicene is a two-dimensional material with a high surface-to-volume ratio,which is compatible with traditional silicon-based electronics and has a tunable bandgap,making it more flexible and diverse in applications such as gas sensors.The electronic structure of silicene is highly sensitive to the adsorption of gas molecules,and its electrical properties are easy to change,thus realizing the rapid detection and analysis of gases.In this paper,based on silicene materials,the gas-sensing performance of doped silicene is analyzed by simulating the adsorption of gas molecules in Al and P doped silicene.Finally,it is found that doping can greatly improve the adsorption characteristics of silicene materials.The main content of this article is as follows.1.Based on the first-principle density functional theory,the geometric structure and electrical properties of 3×3×1 intrinsic silicene were calculated and studied using Materials Studio 2020simulation calculation software.At the same time,the adsorption structure,adsorption energy,charge transfer amount and electronic structure of different gas molecules（H₂,SO₂,NH₃,NO and NO₂）adsorbed on intrinsic silicene were studied.The results show that in addition to being sensitive to SO₂gas,intrinsic silicene opens a band gap of 0.52 e V after adsorption,and has the conditions for gas detection.The band gaps of the other four adsorption systems do not change much,indicating that intrinsic silicene cannot Detects the presence of H₂,NH₃,NO and NO₂.2.Doping silicene materials by Al atom adsorption and substitution methods,studying the adsorption characteristics of Al-doped silicene materials,and analyzing the adsorption process of H₂,SO₂,NH₃,NO and NO₂ gas molecules on its surface.The study found that the Al-adsorbed silicene system is sensitive to H₂ with strong physical adsorption,and the adsorption energy is-0.51 e V;SO₂,NH₃,NO and NO₂ are adsorbed on the two doped materials in a bonded manner,and the Al-substituted silicene system Sensitive to SO₂ and NO,the band gap opens after adsorption,which changes the electrical properties of the material;the Al adsorption silicene system reduces the band gap after adsorbing SO₂,and increases the band gap after adsorbing NH₃ and NO₂,providing feasibility for gas detection.3.The silicene material is doped by the method of P atom adsorption and substitution,and the adsorption characteristics of the doped structure to gas molecules are analyzed.Results The surface P-substituted silicene is very sensitive to nitrogen and oxygen gas NO and NO₂,and its adsorption energy,band gap change,transfer charge and desorption time are all within a reasonable range;Both NH₃ and NO₂ gas molecules are adsorbed on the P-adsorbed silicene material in a bonded manner.Due to the orbital hybridization between the gas molecules and the material,the band gap width increases to 0.34 e V and 0.43 e V,respectively,indicating that the P-adsorbed silicene material It can be used as a gas sensitive material for detecting NH₃ and NO₂.