Strain-induced band modulation of surface F-functionalized two-dimensional Sc2C

Two-dimensional (2D) materials have recently gained tremendous interest in the application of potential electrode materials, and sensor materials. In this paper, strain-induced band modulation and migrant mechanism of monolayer Sc2CF2 under biaxial strain are investigated theoretically. Our investigation reveals that Sc2CF2 is stable under strain because of the negative E-coh. Sc2CF2 can sustain a stress up to 8.35 N/M, which corresponds to the tensile strain limit of about 23%. All the considered strains are within the elastic limit. Sc2CF2 undergoes a semiconductor to metal transition because of the left shift of Sc-d states induced by -10% strain. The critical point from the indirect gap (M to Gamma) to direct gap (M to M) is about 14%, after which the band gap decreases with the increasing tensile strain. We found that the decreasing contribution of Sc atom at valence band maximum (VBM) and conduct band minimum (CBM) states is favorable for the formation of direct band gap under tensile strain and for the transition of semiconductor to metal under compression strain. There exist strong Sc-C and Sc-F interaction under strain through the analysis of spatial charge distribution and electron localization function.