Journal
ACS NANO
Volume 9, Issue 10, Pages 9802-9809Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.5b02753
Keywords
two-dimensional alloy; silicon carbide; semiconductor; first-principle calculation; cluster expansion
Categories
Funding
- U.S. Army Research Office MURI [W911NF-11-1-0362]
- Office of Naval Research [N00014-15-1-2372]
- NSF [OCI-0959097]
- National NSF [11172124]
- Research Funds for the Central Universities [NS2014006]
- China Scholarship Council
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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.
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