Creating Strings Of Single Crystalline Copper Nanobeads By Electrochemical Crystallization

Electrochemical deposition provides a newapproach to fabricate metal structures which may show noble properties in nanophotonics. Base on the untro-thin electrodeposition system, our laboratory have found a variety of morphologies as well as the chemical oscillation during deposition of copper. In this thesis we focus on electrodeposition of copper nanowire to study the formation mechanism as well as its application of the nanobeads strings we found. The deposition system is improved in order to better control of the system. We carry electrodeposition under relatively low driven and steady chemical oscillation was acquired. Our study get deposition product of single crystalline copper without any oxide for the first time. The products are strings of copper nanobeads connected by small necks. The noble crystallization and periodicity makes this structure promising in nanophotonics. We go ahead to study the formation mechanism of this structure and its physical properties.Three main parts are included as follows:1. Single crystalline copper filaments are acquired which consist of strings of nanobeads and necks connecting them, the size of the beads are hundreds of nanometers and the size of the neck are around one hundred nanometers. Experiment observations show that the oscillation in the deposition of copper is cathode process and the narrow necks corresponding to the valley on the voltage signal which means high growth driven. Base on our experiment observation and widely approved oscillation theory we get a primary theory of oscillation mechanism in this system and the formation mechanism of the structure. We also study several important feature of this system including the formation and avoid of coprus oxide in the deposition product, the crystalline structure of the filaments, the growth front at each phase of oscillation and so on.2. We also explore the physical properties of the filaments. Cathodoluminescence (CL) spectroscopy study shows that the neck area emission more photons than other area. Its image under Orthogonal polarization microscope reveals that the area around the necks may change electromagnet waves from one polarization to another. We also study the guidance property of electromagnetic wave by the filaments as optical conductor and some kind of guidance capacity have shown.3. Several control techniques including size of substrate, electrodes and the amount of solution are introduced in order to numerically understand of the system. We also introduces to control the initial nucleus of the ice and reconstruct the system into which contrast experiment is viable. Base on these techniques we acquire chemical oscillation at a relatively low voltage. Quasi-reference electrodes are introduced to pinpoint the potential distribution in deposition system and terminating operation are introduced to study the growth front.