title: Predicting Two-Dimensional Silicon Carbide Monolayers.
abstract: Intrinsic semimetallicity of graphene and silicene largely limits their applications in functional devices. Mixing carbon and silicon atoms to form two-dimensional (2D) silicon carbide (SixC1-x) sheets is promising to overcome this issue. Using first-principles calculations combined with the cluster expansion method, we perform a comprehensive study on the thermodynamic stability and electronic properties of 2D SixC1-x monolayers with 0 ≤ x ≤ 1. Upon varying the silicon concentration, the 2D SixC1-x presents two distinct structural phases, a homogeneous phase with well dispersed Si (or C) atoms and an in-plane hybrid phase rich in SiC domains. While the in-plane hybrid structure shows uniform semiconducting properties with widely tunable band gap from 0 to 2.87 eV due to quantum confinement effect imposed by the SiC domains, the homogeneous structures can be semiconducting or remain semimetallic depending on a superlattice vector which dictates whether the sublattice symmetry is topologically broken. Moreover, we reveal a universal rule for describing the electronic properties of the homogeneous SixC1-x structures. These findings suggest that the 2D SixC1-x monolayers may present a new "family" of 2D materials, with a rich variety of properties for applications in electronics and optoelectronics.
authors.affiliation: Institute of Theoretical Chemistry, Jilin University , Changchun 130023, People's Republic of China.|Department of Materials Science and NanoEngineering, Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Materials Science and NanoEngineering, Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States.
authors.forename: Zhuhua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and NanoEngineering, Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States.
authors.forename: Alex
authors.initials: A
authors.lastname: Kutana
authors.affiliation: Department of Materials Science and NanoEngineering, Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States.
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson
keywords: cluster expansion; first-principle calculation; semiconductor; silicon carbide; two-dimensional alloy