Geometric and Electronic Structures as well as Thermodynamic Stability of Hexyl-Modified Silicon Nanosheet

• Published in: Journal of physical chemistry. C Vol. 117; no. 25; pp. 13283 - 13288
• Main Authors: Li, Feng, Lu, Ruifeng, Yao, Qiushi, Kan, Erjun, Liu, Yuzhen, Wu, Haiping, Yuan, Yongbo, Xiao, Chuanyun, Deng, Kaiming
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 27-06-2013
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electron states; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Methods of electronic structure calculations; Physics; Specific materials; Electrostatic effect; Electronic properties; Nanosheet; Molecular dynamics method; Force field; Theoretical study; Thermodynamic stability; Alkyl radicals; Energy gap; Electronic structure; Graphene; Density functional method; Silicon
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp402875t

The successful synthesis and outstanding properties of graphene have promoted strong interest in studying hypothetical graphene-like silicon sheet (silicene). Very recently, 2D silicon nanosheet (Si-NS) stabilized by hexyl groups was reported in experiment. We here present an atomic-level investigation of the geometric stability and electronic properties of Si-NS by density functional calculations and molecular dynamics simulations. The most stable structure of the hexyl-modified Si-NS corresponds to the one in which the hexyl groups are regularly attached to both sides of the sheet, with the periodicity of the hexyl groups on the sheet being 7.17 Å, in good agreement with the experimental value of 7.1 Å. The electrostatic repulsion effect of the hexyl groups could be an important reason for the favorable structure. The electronic structure of the hexyl-modified Si-NS shows a direct band gap that is not sensitive to the length of the alkyl group but sensitive to the strain effect, which can be used to tune the gap continuously within the whole strain range we considered. Finally, both the first-principles and the force-field-based molecular dynamics simulations show that the most stable structure of the hexyl-modified Si-NS could maintain its geometric configuration up to 1000 K.