Preparation And Characterization Of Metal-Doped Copper Oxide Films

Copper oxide mainly consists of copper oxide (CuO) and cuprous oxide (Cu2O). It has many advantages, such as excellent optical and electrical properties, richness in earth content, non-toxic and low cost, and so on. Compared to CU2O, CuO is more stable and easily prepared, and its band gap is more matched with the solar spectrum structure enabling it to absorb more sunlight and reach higher photoelectric conversion efficiency. Thus, CuO is a superior candidate for solar cell applications. The properties of metal-doped CuMO thin films are rarely reported, studying their optical, electrical and magnetic properties has promising application prospects. In this thesis, copper oxide and metal doped copper oxide thin films were prepared on Si (100) and ITO glass substrates by RF and DC magnetron co-sputtering. The crystal structure, surface morphology, component composition, electrical, optical and magnetic properties of the oxide copper thin films as well as the metal-doped ones were comprehensively analyzed.The copper oxide thin films exhibiting great crystallinity with (002) preferred growth orientation were deposited on Si (100) and ITO glass substrates by radio frequency magnetron sputtering. X-ray diffraction (XRD) patterns of the obtained films show a sharp diffraction peak of (002) direction, indicating excellent crystallinity. Scanning electron microscopy (SEM) images show the surface of the films are smooth and dense, the average particle size is about 32-70 nm. For the as-deposited films, energy dispersive spectroscopy (EDX) analysis shows the ratio of Cu and O is about 1.1-1.3, which closes to the stoichiometric CuO, and Cu exists as the form of Cu2+according to X-ray photoelectron spectroscopy (XPS) analysis. The resistivity of the film measured by the four point probe method is about 0.05-3.702 Ω·cm. Ultraviolet visible near infrared (UV-VIS-NIR) spectrophotometry meter measurements show a maximum transmittance of 46.6% at 1030.53 nm, and the calculated optical band gap is 2.84 eV.Metal-doped copper oxide thin films (CuO-Mn:Al and CuO-Co:Al) were prepared by RF and DC co-sputtering, and the obtained films were annealed. The structure was analyzed by XRD. The surface morphology and component composition were analyzed by SEM, EDX and XPS. The changes of resistivity, optical band gap and magnetism were studied by the four probe method, UV-VIS-IN spectrophotometer and vibrating sample magnetometer (VSM), respectively. Combined with the calculated lattice constant and EDX, XPS measurement results, it can be concluded that Mn:Al or Co:Al was successfully doped into the lattice. The resistivity decreases, the band gap values increase and the non-magnetic material transforms to ferromagnetic material due to doping for metal-doped copper oxide films. The coercivity of the film doped with Co:Al (401 Oe) is greater than that of films doped with Mn:Al (270 Oe).