The growth and optical properties of CdSSe nanosheets.

We have investigated the growth of ternary CdSSe nanostructures by physical vapor transport, specifically aiming at the synthesis of CdSSe nanosheets. CdSSe nanostructures with various S mole fractions are grown at growth temperatures less than 800 degrees C and photoluminescence from these nanostructures covers the entire visible spectral range. Morphological evolution from nanowires to nanosheets is observed as increasing growth temperatures due to the change of relative dominance in the growth mechanism from vapor-liquid-solid to vapor-solid. Nanosheets whose widths extend several tens of micrometers are successfully synthesized. However, nanosheets show a strong suppression effect of S incorporation when the growth is dominated by the vapor-solid mechanism. A micro-photoluminescence study shows high optical quality of individual CdSSe nanostructures with polarization anisotropy ratios rho ~ 0.1. In addition, lateral heterostructure CdS/CdSe nanosheets are successfully synthesized by two step growth. Strong red and green emissions are observed by selective laser excitations focusing at the center and edge parts of these heterostructure nanosheets, respectively. These heterostructure CdS/CdSe nanosheets may be useful for multicolor light emitting devices.