Study of Electronic and Optical Properties of CuInSe2 Nanowires

The electronic and optical properties of the CuInSe2 nanowires have been investigated via density functional theory. We have used numerical atomic orbital bases set with local-density approximation. The norm-conserving pseudopotentials of Troullier and Martins have been used. In our calculation we used nanowires in two shapes of hexagonal and triangular with their diameters ranging from 8 to 15 A in the (1–10) growth direction. The geometrical parameters are in good agreement compared with other experimental or theoretical results. We show that for the nanowires there is a significant contraction of the Cu–Se and In–Se bond lengths at the edge of the wires (4.7%); as for the wires at the center, it is 2.6%. Moreover, we have investigated the band structures and atom-projected density of states of the nanowires. These studies confirm that CuInSe2 nanowires are semiconductors with a direct band gap. These studies also show the existence of hybridization between Cu-d with Se-p states in the middle valence su...