Study On The Preparation Of Ⅱ-Ⅵ Semiconductor Materials-SiO₂ Composite Colloidal Particles

Due to outstanding photo-electronic properties, II-VI semiconductormaterials have shown great prospect in optoelectronic conversion, sensor,luminescence and biological imaging. It is necessary to fabricatesemiconductor-inert materials because of stability and consistency ofsemiconductor materials reacting with organism. Base on this idea, we try toprepare II-VI semiconductor-silica composites and have prepared CdTe-SiO2doped composite microspheres, core-shell composite nanoparticles and films. First, based on prepared high quality CdTe nanocrystals aqueous, we havesynthesized monodisperse, doped CdTe-SiO₂ composite microspheres by a facileand prevalent method. Without any modifying or altering, the CdTe nanocrystalscan be incorporated into SiO₂ matrix by sol-gel method in St?ber system. Thismethod changing the idea that the nanocrystals have to be modified by silaneligands with thio or amido group before introducing into silica, moreover, themethod has simplified the process. The composite microspheres can be controlledfrom 150 nm to 1.4 μm in diameter. We have prepared four kinds of CdTenanocrystals with different stabilizers and it is found that MPA molecular is thebest stabilizers for synthesizing CdTe-SiO2 composites. Because of the protectingof silica matrix, the nanocrystals in composite microspheres are more stable tosurroundings changing than the CdTe in solution. The mechanism of reaction hasalso been invested and more kinds of composites are expected to be synthesizedwith this method. The CdTe-SiO2 composite microspheres can be used as buildingblock to prepare photonic crystals in future.In order to prepare CdTe-silica composite nanoparticles, the nanocrystalshave been coated with a thin silica film by grafting silane ligands with epoxy, atthe same time, the nanocrystals bave been dissolved in ethanol. The CdTe-silicacomposite nanoparticles can be modified with functional group by grafting silaneligands in ethanol. The functional CdTe-silica nanoprticles will show more effectin biological imaging, et al.We have also synthesized composite colloid particles with silica and animportant semiconductor-ZnO, and the ZnO/SiO2 core/shell composite particlesor films have been obtained. ZnO microparticles or film have been proved to becoated with silica directly by a sol-gel method, the ZnO need not any pretreatmentand the thickness of silica shell are controllable. We have coated three kinds ofdifferent ZnO particles and one kind ZnO thin film with silica shell, respectively.Without doubt, the stable silica shell on ZnO particles or films will help ZnOextend its application in more fields. When the ZnO cores are etched, silicahollow microparticles or hollow film are obtained. These hollow particles or filmwill show potential application in drug releasing and micro-reaction room.In order to study the consistence of II-VI semiconductor and silica, we haveextended more II-VI materials to be coated with silica. Based on synthesizing ofZnO/SiO2 core/shell particles and films successfully, HgO, CdS and CdCO3(precursor of CdO) microparticles have also been coated with silica directly bythe same method. We make a presupposition about the interface consistence ofII-VI semiconductor materials and silica based on our experiment result andreference: II-VI semiconductor materials can all be coated with silica directly by asimple sol-gel method because of good interface consistence between them. Webelieve that the interface consistence is the idiographic embodiment of "similitudeis compatible". This presupposition provides theoretical direction of synthesizingmore composites of II-VI semiconductor materials and silica, moreover, thecomposites can help II-VI semiconductor materials show more effect inoptoelectronic fields.