The Synthesis And Characterization Of ZnO Nanomaterials On Sapphire Substrate By CVD Method

As the third generation of direct wide bandgap semiconductor material,ZnO has unique characters of piezoelectric and photoelectric.At the same time,the properties of ZnO materials significantly dependent on its morphology and structure,the characteristic its rich morphological structure determines its broad application prospect in the field of nano mechanical,photocatalytic,electrochemical and sensor,and so on.ZnO nanoparticles,nanowires,nanotubes,nanobelts,nanorings,nanotubes,nanonails and other structures have been successfully prepared by various methods.It has become a new research trend that these nano-pieces assemble themselves into more complex ZnO nanostructures with regularly arranged and good crystal quality.In this paper,the controlled growth of several unique ZnO structures with different morphlogy,highly aligned nano arrays on the sapphire substrate has been realized by CVD(chemical vapor deposition)method.Besides,we have analyzed its morphology,growth mechanism,optical and electric properties,etc.The research content are as follows:(1)The simutanious growth of nopolar a-plane ZnO film and oblique aligned nanowire arrays have been realized on Au coated r plane sapphire substrate under growth temperature of 900 degree by a simple and novel method of CVD.The size of the nanowires was controlled by changing the thickness of coated Au films r-plane sapphire on the substrate,and the density of the nanowires was controlled by changing the ratio of Zn to O.The growth mechanism of the product was also analyzed.(2)Three-dimensional(3D)crosslinked nanobelt arrays were successfully grown on Au coated r-plane sapphire substrate when the growth temperature heated up to 960 degree.This unique 3D block building combines the excellent properties of nanobelts and nanofilms.The width of the nanobelt is adjusted by changing the experimental parameters,and it shows a remarkable persistent photoconductive effect.(3)we adopt the polar surface(c-plane)and nonpolar surface(a-and m-plane)of sapphire as the substrate in our experiment to adjust the epitaxial direction of ZnO nanowire arrays,the ZnO nanowire arrays eventually formed into different cross angles with the substrate.The difference of cross angles is related to the lattice matching direction between ZnO nanowires and the substrate.