Predicting Two-Dimensional Silicon Carbide Monolayers

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• 作者：Zhiming Shi ; Zhuhua Zhang ; Alex Kutana ; Boris I. Yakobson
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：October 27, 2015
• 年：2015
• 卷：9
• 期：10
• 页码：9802-9809
• 全文大小：590K
• ISSN：1936-086X

文摘

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 (Si_xC_1鈥?i>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 Si_xC_1鈥?i>x monolayers with 0 鈮?x 鈮?1. Upon varying the silicon concentration, the 2D Si_xC_1鈥?i>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 Si_xC_1鈥?i>x structures. These findings suggest that the 2D Si_xC_1鈥?i>x monolayers may present a new 鈥渇amily鈥?of 2D materials, with a rich variety of properties for applications in electronics and optoelectronics.