Preparation Of Cu₂O Nanowire Arrays And Their Applications In Bidirectional Devices

Metal Oxides semiconductors are attractive for their special physical properties and chemical properties. And for their sufficient reserves on earth like Si, oxides are promising materials in future applications.Nanotechnology, as a major discovery in the history, has become the forefront of modern science, causing a lot of new changes in information, medical, automation, energy and human life. Metal oxide nanostructure is a combination of these two important fields and is the focus of the current work. Among all oxides, cuprous oxide has become a hot material, because of its unique physical properties and its potential in applications.The experiment is aimed at finding a simple way to directly grow copper oxide nanowires on a copper substrate and exploring the applications in devices, mainly carries out the following tasks:1. Synthesis of cuprous oxide nanowire arraysA mixed solution of sodium hydroxide and ammonium persulfate was used to react with a copper substrate at room temperature, one-dimensional Cu(OH)2nanowires was formed as precursor. The cuprous oxide nanostructures were prepared by thermal decomposition of Cu(OH)2precursor. XRD, SEM, TEM and HRTEM were used on the synthetic materials to determine characteristics, testing the material morphology, structure and composition. A two-step heating method was proposed to optimize the preparation process. The new nanostructure morphology results in higher effective area surface than normal nanowire. Morphology of template is smooth nanowires with diameter of100nm, pod-like nanowires were obtained after annealing, radius changed from50nm to200nm surrounding to radius of template nanowire, surface area has doubled. By heating the precursor in300℃and500℃separately achieved a non-situ conversion, morphology changed from the template that product morphology and topography changes. The final copper oxide sample was well crystallized.2. Exploration of the contact characteristics between cuprous oxide and metalThere are three contact effects:resistance switching effect, Ohmic contacts and Schottky contacts, the paper studies the Schottky contact. Cu2O can form a Schottky contact in contact with some metals, such as Ti, Al, Cu, Ru, etc., Cu and Al are selected because they are the most commonly used metal in a semiconductor process. Cu and Al here are used as the bottom electrode and the top electrode, respectively. Schottky contacts are formed at both sides of Cu2O. Cu2O was grown on the Cu substrate as bottom electrode, naturally formed a Schottky contact. When the aluminum layer was evaporated on surface as the top electrode, the resulting device is equivalent to two Schottky diodes reverse in a series with anodes connected together. The device showed good trigger characteristics, when the inputting voltage reaches to18V, the IV curve turned back, a turning point appears, and an explanation was proposed. The leakage current of devices is related to the junction areas and the value is larger than general devices. To prepare the regulator devices, a layer of TiO2was added between Cu2O and Al to form a PN junction, voltage regulation was obvious.