Influencia de la geometría y dopaje en las propiedades electrónicas de la hoja SiC

Abstract

In this work it is presented a study concerning the effect of geometry and nitrogen doping on the electronic properties of the silicon carbide (SiC) sheet by means of the Density Functional Theory (DFT) at the level of Local Density Approximation (LDA). Two different basic geometries were used to model the SiC system: rectangular (arcmchair type; Si$_{12}$C$_{12}$H$_{12})$ and triangular (zig-zag type; Si$_{12}$C$_{12}$H$_{10})$. It was found that both systems are stable. Although a semiconductor behavior was recognized for both models, the gap energy shows strong dependence on the geometry. While the calculated gap energy for the rectangular cluster was 1.15 eV, for the triangular geometry it was twice as large (2.75 eV). A transition from covalent to ionic character by controlling the geometry of the SiC cluster is reported. The calculated dipolar moment for the triangular and rectangular cluster was 12$\times $10$^{ - 3}$ and 5271.7$\times $10$^{ - 3}$ Debye, respectively. Finally the effect of nitrogen doping on the structural stability and electronic properties of the systems are discussed.