| Low dimensional nanostructures have attracted increasing interests in worldwide for their unique properties in physics and chemistry. It is reported that properties of materials are related to their mesostructures and one can design the nanostructures of materials to enhance the performances. Normally a ’Bottom-up’ method was used to design much complex nanostructures. However, due to the limitation of materials preparation and characterization, there are still many challenges in the research of nanostructures controllable synthesis with optimal composition and structure. Here a facilitate method have been put forward to realize such ’Bottom-up’ construction. In this paper, rich Te-CdTe nanowires and CdTe/Te superlattice nanowires, PbTe and rich Te-PbTe nanowires embedded in porous anodic alumina (PAA) template have been successfully fabricated by direct current electrochemical deposition and pulsed electrochemical deposition method respectively. The composition and phase, morphology and structure of nanowire arrays have been characterized by XRD and EDS, FE-SEM and TEM; the preparation parameters were optimized by an electrochemical workstation and the electrical performance were tested by four point probe surface resistance tester.1. The porous anodic alumina (PAA) templates used in the experiment were synthesized by a two-step anodic oxidation method in0.3mol/L oxalic acid electrolyte solution under constant voltage40V. PAA template have approximately uniform pore size, straight and orderly nanochannel with diameter of40-60nm and density of1010-1011/cm2. After being sprayed a layer of gold onto back of the template, PAA could be served as the working electrode in electrodeposition process.2. CdTe-Te nanowire arrays, embedded in PAA template have been successfully fabricated by a pulsed electrochemical deposition process. The preparation parameters were optimized by electrochemical cycle volt-ampere (CV). The component, structure and morphology of nanowire arrays deposited in different solvent were studied, it is indicated that nanowires prepared in water solvent had rough and flawed surface, whereas highly ordered, uniform in diameter and straight nanowire arrays with smooth surface were fabricated in the solvent with adding ethanol, and a moderate amount of ethanol contributed to form the superlattice structure. The dense and uniform CdTe/Te superlattice nanowire arrays with diameter of about50nm, have been successfully prepared at optimized deposition condition under Ethylene glycol (EG)/ethanol/water solvent conditions. The composition and structure of nanowire arrays have been controlled by changing deposition potential and deposition time. The electrical performance were tested by Ⅰ-Ⅴ curve, the result showed that the semiconductor contact characteristics were different for the samples prepared under different solvents:the sample synthesized under water solvent showed Schottky barrier contact. The sample prepared under volume ratio of ethanol and water was2/3solvent showed ohmic contact, both CdTe/Te supperlattice structure and sample prepared under volume ratio of ethanol and water was1/4solvent were Schottky barrier contact, and the shape of Ⅰ-Ⅴ curve was similar.3. Pb-Te nanowire arrays were prepared by template-electrochemical deposition method. The deposition parameters determined by CV test. The Polycrystalline PbTe nanowires were synthesized by direct current electrodeposition at constant voltage-0.3V and rich Te/PbTe nanowire arrays were prepared by pulsed electrodeposition at voltage VpbTe=-0.3V, Vte=-0.17V, The atomic ratio of Te to Pb was1.3:1approximately. The electrical performance were tested by Ⅰ-Ⅴ experiment, the result showed that the polycrystalline PbTe nanowires present an unique semiconductor nonlinear characteristic curve; the Ⅰ-Ⅴ curve of rich Te-PbTe nanowire arrays also showed atypical nonlinear behavior, which means good Schottky barner contact performance. |
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