Synthesis, Optical Properties Of Ⅱ-Ⅳ Semicondutors And Doped Nanomaterials

â…¡-â…£nanocrystals,as a class of special semiconductor nanomaterials, have the similar regularity of atomic arrangement with crystals.As a result of quantum size effects,their optical and electrical properties strongly depend on the size of nanocrystals,the surface structure,crystal structure and the performance of nanocrystals have attracted more attentions.In this paper,â…¡-â…£semiconductors and their doped nanomaterials were synthsizied with colloidal method and studied the relationship between the morphology,structure of materials and the optical properties.Main points as follows:α-Cyclodextrin modified CdSe/CdS nanoparticles were successfully synthesized with hydrothermal method.Techniques of AFM,TEM,EDS, FTIR,UV-vis absorbance and photoluminescence spectra were used to characterize the morphology,composition and optical characteristic of the synthesized nanoparticles.The effects of precursor ratios,reaction times and the light stability of the nanoparticles were investigated.The results showed that the as-synthesized nanoparticles were dot-shaped and their average size was 15 nm,had hexagonal single crystal structure.The red shift in both absorption and fluorescence emission spectra of CdSe/CdS nanoparticles are resulted from the presence of the CdS shell.The obvious defects in the lattice and the boundary between CdSe and CdS were not observed.The sizes and size distributions can be adjusted by precursor ratios and reation times respectively by the presence ofα-Cyclodextrin.ZnSe nanoparticles were prepared using alkylamines as ligating solvent by microwave-irradiation method.The differences of morphologies in the effect of alkylamines and microwave variables were investigated.The results show that there is an inverse relationship between the size of nanoparticles and the length of the alkylamine.The average sizes were increased with the duration of irradiation time. Microwave irradiation power affects the sizes and shapes of ZnSe materials because of the movement and polarization of amine molecules under the rapidly changing electric field of the microwave reactor.Mn- Co- doped ZnSe nanoparticles were prepared by microwave-irradiation method.The effects of different doped transition metals and the dope amount on the morphology and optical properties were investigated.The results showed that the Mn- doped ZnSe nanoparticles were orange powder and the average size was 200-500 nm. They had structured surface and single crystal wurtzite structure.Three emission peaks,433 nm,487 nm,530 nm,were detected in the photoluminescence spectrum.Co- doped ZnSe nanoparticles were yellow-green powder and the average size was 500 nm.They had structured surface and single crystal wurtzite structure.Two emission peaks,486 nm,527 nm,were detected in the photoluminescence spectrum.Mn-doped ZnSe nanowires were prepared by hydrothermal method usingα-cyclodextrins as stabilizer and zinc acetate,manganese acetate and Na₂SeSO₃ aqueous solution as precursor.The as-prepared Mn-doped ZnSe nanowires were all typically single well-crystallized structure and had zinc blende structure.The average length of the nanowires was about 2-3 um and average diameter was 80 nm.Experimental results showed that a sharp absorption band appeared at 360 nm in the UV-vis absorbance spectra of Mn-doped ZnSe nanowires.The corresponding photoluminescence spectrum with 350 nm excitation showed signs of two distinct emission bands centered at 432 and 580 nm.