Microstructures And Properties Of Cuprous (Cupric) Oxide Films By Thermal-Oxidated

Electroless plating is a metal deposited and controlled autocatalytic deoxidization process. Chemical reaction happens on catalyse surface in Electroless plating process. Electroless plating is an advanced technology to achieve micron and nanometer films deposit. Along with the development of micro-electronics industry, Electroless plating has evolved with a lot of research works as a method to metalize nonconductor's surface. Electroless plating has been proposed as an potential technology for the preparation of copper seed layer in ULSI metallization. The microstructures and properties of this seed layer have important effects on the properties of subsequent electrodeposited layers. Therefore, it is essential to research the microstructures and properties of Electroless plating. This paper fabricates electroless copper film with good properties by optimizing conventional bath composition and processing parameters.At present, interests on the nanowires (nanorods) are focused on the fabrication technique.Because of the special one-dimensional nanometer structure of nanowires (nanorods), it shows a serials of excellent properties in aspects of mechanics, optics, electrics, magnetics, calorifics and hydrogen storage. It is not only the ideal system to study basic physical properties and measure dimensionality of electrics, optics, magnetics , calorifics, but also plays an important role in phototube parts as the connect and function element. People has synthesized kinds of nanowires (nanorods) by many methods, and successfully measured their physical properties. In this paper, Thermal oxidation under controlled conditions has been used to prepare copper oxide thin films. including cuprous oxide and cupric oxide ,they are both p-type semiconductor. Especially, CuO nanowires (nanorods) can be synthesized on the copper substrate by this method, without any catalyst and template.Based on above methods, nanocrystalline copper films on the glass have been fabricated by electroless plating with the addition of surfactant, sodium dodecyl benzene sulfonate (SDBS). Cu2O and CuO thin films as well as CuO nanowires (nanorods) have been synthesized by the thermal oxidation of the as-prepared nanocrystalline copper thin films. Microstructures and properties of these thin films are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), atom force microscope (AFM), transmission electron microscope (TEM), fourier-transform infrared transmission (FTIR), UV-vis spectrophotometer, etc. The main results are shown as follows:1. Nanocrystalline copper thin films have been synthesized by electroless plating. Microstructure analysis show that an obvious (111) texture exits in the copper thin films. The grain size and the intensity of (111) texture of copper thin films increases with increasing deposition time. The transition from a random grain growth to one preferred on (111) plane and the expense of the (111) orientated grains are responsible for this texture development in the Cu film. Nanocrystalline copper thin films are composed of small nodules which composed of several grains. When deposition time increases,These nodules grow and connect with each other, Nanocrystalline copper thin films are formed with the increasing of nodules quantities. Morphologies observations reveal that 1min deposition is able to achieve a continuous copper thin film. A good adhesion strength exits between the Cu film and the glass substrate.2. The oxidation behaviors of electroless copper thin films, 100 nm thick in the range of 100°C-600°C have shown that Cu2O can be formed at the initial oxidation stage of 250°C. at the same time, Oxidation is incompleteness, and Cu is also in existence.While at the temperature of 300°C, a mixture of Cu2O and CuO is formed and Cu2O evolves into pure CuO above 350°C. The oxidation time also have played a key role in the microstructure and surface morphologies. CuO nanowires with the diameter of about 10-15 nm and the length of 200-300 nm have been observed at 300°C for 8 h. Copper oxide films have higher transmittance in the visible and IR region, while almost completely opaque in the UV region. The variation of optical transmittance spectra depends on the composition and microstructure of oxide films. The band gaps are 1.93-1.98 eV and 2.2-2.4 eV for pure CuO and the mixture of Cu2O and CuO, respectively.3. A mixture of Cu2O and CuO is formed during the oxidated process of nanocrystalline copper films, and Cu2O evolves into pure CuO. It can be found that the optimum temperature is between 300 oC and 400 oC for a 100 nm thick thin film at the oxidation time of 1 h. No nanowires are observed when the oxidation temperature is lower or higher than this range of temperature. The number of nanowires decreases with the prolonging of oxidation time at 350 oC. However, few nanowires could be seen when the thin film was oxidized at 400 oC. film thickness has played a key role in formation of nanowires ,The increase of film thickness is benefit to forming nanowires. The transmittance of CuO nanowires increases with the increasing of introduced wavelength and decreases with the increase of film thickness. The band gaps of CuO nanowires are in the range of 1.94 eV-2.03 eV.