Theoretical study of electronic and mechanical properties of GeC nanowires

In this work, we present a density functional study of the electronic band structure, the Young's modulus and Poisson ratio of hydrogen-passivated germanium carbide (GeC) nanowires, with diamond structure and grown along the [0 0 1] and [1 1 1] crystallographic directions, as function of their diameter. The results obtained are compared with those calculated for the corresponding silicon carbide (SiC), germanium (Ge) and silicon (Si) passivated nanowires. The band gaps of GeC and SiC passivated nanowires are quite similar between them and larger than those of the Ge and Si nanowires. For all studied nanowires, the Young's modulus have a lower value than the bulk one and it increases as function of the diameter converging to the bulk value. Both carbide nanowires (SiC and GeC) show higher Young's modulus values than the nanowires without carbon (Si and Ge). Moreover, the nanowires grown along [0 0 1] direction show a lower Young's modulus in comparison to those grown along [1 1 1] direction, since the covalent bonds are oriented along this direction. Finally, the results show that for both crystallographic directions the carbide nanowires have a more compact structure in comparison to the corresponding non-carbide ones, and then the former nanowires have a higher resistance to be deformed.