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 to1.71 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.