Its Light Absorption Properties Of Semiconductor CdS <sub> 1-x </ Sub> Se <sub> X </ Sub> Nanomaterials

The preparation, characterization and optical properties of solid solutionsemiconductor CdS_1-xSe_x nanocrystals were studied in this paper. At first, solid solutionsemiconductor CdS_1-xSe_x nanocrystals were synthesized using CdCl₂·2.5H₂O, S powderand Se powder as starting materials and ethylenediamine as solvent via solvothermalmethod. The experiment was conducted at 180℃for 12h and the composition of productswas changed by varying the amounts of S powder and Se powder. The products werecharacterized with XRD and the amounts of S powder and Se powder were determined byXPS measurements. The results showed that S to Se ratios in the solid solutionsemiconductor CdS_1-xSe_x nanocrystals were almost the same as ratios of reagent. Themorphology and size of the solid solution semiconductor CdS_1-xSe_x nanocrystals wereobserved by TEM method, including the determination of crystal phase by SAED. Latticeconstantsαand c of the products were calculated by XRD spectra. The relationship oflattice constants vs. selenium atom fraction x was studied. Lattice constantαvariesfrom 0.41287nm(CdS) to 0.42944nm(CdSe) and lattice constant c varies from0.66830nm(CdS) to 0.70024nm(CdSe), which closely agreed with the Vegard law. Afterthe products were classified by centrifugal method, their UV-Vis absorption spectra weremeasured and blue shift was observed. The bandgaps of products were determined withUV-Vis spectra. The value of band-gap decrease from 2.56eV of CdS to 1.76eV of CdSewith increase of selenium atom fraction x. The relationship of bandgaps vs. selenium atomfraction x was fitted, which showed that modulating band-gap of semiconductor by varyingcomposition of solid solutions was possible.