Electronic behavior of organic molecules adsorbed on monolayer SiC

Studying the adsorption of organic molecules is a good approach for exploring the electronic conducts of two-dimensional (2D) materials. We utilized density functional theory (DFT) to research the structure and electronic behaviors of organic molecules (Tetracyanoquinodimethane(TCNQ), Tetracyanoethylene(TCNE), Tetrathiafulvalene (TTF)) in the SiC adsorption system. After organic molecules are adsorbed on monolayer SiC, the charge difference density (CDD) and the plane average CDD indicate the presence of charge transfer between monolayer SiC and organic molecules. The research results indicate that the impurity energy level appears in the band structure and is contributed by organic molecules. Facts prove that the TCNQ, TCNE, and TTF molecules may inject additional carriers into the SiC layer. TCNQ and TCNE molecules are the electron acceptors, while TTF molecule is the electron donor. The p-type doping and n-type doping were achieved in monolayer SiC, and induce effective p-type doping behavior. Because TCNQ, TCNE, and TTF molecules inject additional holes or electrons into the monolayer SiC, the dimension of the work function can be regulated, expanding the field emission capability range of SiC-based electronic devices. The current-voltage (I-V) curves reveal that after organic molecules adsorbed on monolayer SiC, the transport current capability of the n-type doping system is stronger than the p-type doping system. Therefore, SiC system electrical characteristics may be regulated by organic molecule adsorption. Our work provides a theoretical foundation for SiC application in nano electronic device.