Electronic and Optical Properties of SnGe and SnC Nanoribbons: A First-Principles Study

Structural, electronic, and optical properties of one-dimensional (1D) SnGe and SnC with two types (armchair and zigzag) and different widths are studied by using first-principles calculations. The atoms of these structures in edges are passivated by hydrogen. The results show armchair SnGe and SnC nanoribbons (A-SnXNRs, X=Ge, C) are the direct semiconducting and divided into three distinct families W=3p, W=3p+1, and W=3p+2, (p is a positive integer). By increasing width, the band gaps converge to 1.71 eV and 0.15 eV for A-SnCNRs and A-SnGeNRs, respectively. Furthermore, the position of the first peak of the dielectric function in both of them occurs in their value of direct band gap at Г point. also, the absorption coefficient for 9, 11, 13 A-SnCNRs displays that there is no absorption at the lower energy range from 0 to 1.2 eV, whereas absorption characteristics for 9, 11, and 13 A-SnGeNRs appeared at near-infrared to the visible spectrum. These results can provide important information for the use of Group IV binary compounds in electronic devices.