Structural and optical properties of CdSxSe1-x nanowires

Abstract

We studied the structural and optical properties of pseudobinary CdSxSe1-x alloy nanowires synthesized by pulsed laser deposition. Experimentally, the lowest direct optical band gap of these single-crystalline and straightly grown alloy nanowires was found to scale linearly with the composition x as in the case of the mean lattice constant of the hexagonal wurtzite crystalline CdSxSe1-x nanowires. In contrast to the well-known optical band gap bowing of semiconductor alloys, the CdSxSe1-x alloy nanowires did not exhibit such bowing. The relaxation of the effective strain resulted in the disappearance of the maximum value of the short-range order parameter of the nanowires at x=1/2, which yielded a reduction in the intrinsic band gap bowing parameter. We also observed that the intensity of the photoluminescence resulting from the band gap edge emission of the nanowires increases with increasing x, which was theoretically explained by assuming that the diffusion depth for the surface-recombination satisfies the concentration-weighted average.