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Title: Tunable gaps and enhanced mobilities in strain-engineered silicane

The recent demonstration of single-atom thick, sp{sup 3}-hybridized group 14 analogues of graphene enables the creation of materials with electronic structures that are manipulated by the nature of the covalently bound substituents above and below the sheet. These analogues can be electronically derived from isolated (111) layers of the bulk diamond lattice. Here, we perform systematic Density Functional Theory calculations to understand how the band dispersions, effective masses, and band gaps change as the bulk silicon (111) layers are continuously separated from each other until they are electronically isolated, and then passivated with hydrogen. High-level calculations based on HSE06 hybrid functionals were performed on each endpoint to compare directly with experimental values. We find that the change in the electronic structure due to variations in the Si-H bond length, Si-Si-Si bond angle, and most significantly the Si-Si bond length can tune the nature of the band gap from indirect to direct with dramatic effects on the transport properties. First-principles calculations of the phonon-limited electron mobility predict a value of 464 cm{sup 2}/Vs for relaxed indirect band gap Si-H monolayers at room temperature. However, for 1.6% tensile strain, the band gap becomes direct, which increases the mobility significantly (8 551 cm{sup 2}/Vsmore » at 4% tensile strain). In total, this analysis of Si-based monolayers suggests that strain can change the nature of the band gap from indirect to direct and increase the electron mobility more than 18-fold.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Materials Science and Engineering, the Ohio State University, Columbus, Ohio 43210 (United States)
  2. Department of Chemistry and Biochemistry, the Ohio State University, Columbus, Ohio 43210 (United States)
Publication Date:
OSTI Identifier:
22275700
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BOND ANGLE; BOND LENGTHS; COMPARATIVE EVALUATIONS; COVALENCE; DENSITY FUNCTIONAL METHOD; ELECTRON MOBILITY; ELECTRONIC STRUCTURE; ENERGY GAP; FCC LATTICES; GRAPHENE; HYDROGEN; LAYERS; PHONONS; SILICON; STRAINS; TEMPERATURE RANGE 0273-0400 K