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Tuning the Electrical Conductivity of Ti₂CO₂ MXene by Varying the Layer Thickness and Applying Strains

Zhang, Yaqing, Zha, Xian-Hu, Luo, Kan, Qiu, Nianxiang, Zhou, Yuhong, He, Jian, Chai, Zhifang, Huang, Zhengren, Huang, Qing, Liang, Yunxiao, Du, Shiyu
Journal of physical chemistry 2019 v.123 no.11 pp. 6802-6811
electrical conductivity, metalloids, physical chemistry, semiconductors
MXenes have attracted intensive attention because of their widespread applications. As a well-studied member of the MXene family, Ti₂CO₂ has been demonstrated to be semiconducting with ultrahigh carrier mobility, acting as a candidate material for electronic devices. In this work, the influence of layer thickness on the electrical conductivity of Ti₂CO₂ is investigated combined with first-principles density functional calculations and the Boltzmann transport theory. Because of the layer interaction-induced band splitting, the band gap of Ti₂CO₂ generally decreases with increasing layers. Based on the generalized gradient approximation, the band gap in monolayer Ti₂CO₂ is determined to be 0.260 eV, which decreases to 0.0369 eV in the five-layer configuration. Further, the strain influence on the electronic structure of the multilayer Ti₂CO₂ is studied. With increasing compression strains perpendicular to the basal plane, the configuration is found to transform from a semiconductor to a semimetal, then to a semiconductor, and at last to a metal. This result implies that the electronic property of the multilayer Ti₂CO₂ can be efficiently manipulated by strain and that the multilayer configurations could be applied in strain sensors. Moreover, our work may open a door to realize bulk semiconductors through compression of accordion-like multilayer MXenes.