Study Of Structure And Optical Properties On Cu-doped ZnO Thin Films Prepared By PLD

ZnO is a direct band gap of wide band gap semiconductor material with a hexagonal structure at room temperature band gap 3.37ev, exciton binding energy of up to 60mev, because of its very excellent optical properties and optoelectronic devices in the great value and as the "twenty-first centuries semiconductors. "Non-doped ZnO is usually a typical n-type semiconductor, this is due to structural defects in ZnO. However, for ZnO doped with different doping and to study its various properties after the increasingly become hot. In this thesis, KrF excimer laser deposition technique and systematically studied the Cu-doped ZnO thin film preparation, structure and optical properties. The main contents are:In the back end of the vacuum 2.0×10-5Pa, the substrate temperature were selected to room temperature,100℃,200℃,300℃,400℃copper doped ZnO film. X-ray diffraction of samples (XRD) spectra showed that all samples appeared ZnO (002) crystal plane diffraction peak, and no other diffraction peaks. This shows that we prepared samples with hexagonal structure, the film is highly C-axis preferred orientation. At the same time, only the sample (002) diffraction peaks, which indicates that Cu ions in the film did not form new compounds, but in the form of impurities in the ZnO film. As the substrate temperature, the sample (002) diffraction peaks become more intense, the intensity gradually increased.Choose a fixed substrate temperature of 400℃, and then at 2.0×10-2Pa,2.0×10-1Pa, 2.0×100Pa, and the oxygen pressure 2.0×101Pa sample preparation. XRD spectra showed that oxygen pressure in different copper-doped ZnO thin films prepared there are unique, sharp ZnO (002) diffraction peak and found no other peaks. It can determine the location of Cu doping in the ZnO crystal lattice, there is no other crystalline oxide. In the 2.0×10-1Pa oxygen pressure the minimum FWHM of samples, the maximum grain size. Analysis, oxygen pressure in the sample preparation and oxygen balance gain and loss of basic, good quality thin films. Photoluminescence spectra of samples show that all samples are in the vicinity of the strong 378nm UV emission, corresponding to the energy of 3.28eV, the center also found that there is a 475nm blue band with the corresponding energy of 2.62eV. Analysts believe that as the center of the 475nm blue light from the sample with zinc vacancy and zinc interstitial defects, and are visible deep level emission (DL).Oxygen pressure in the 2.0×10-1Pa, substrate temperature is 400℃, annealing for 1 hour uniform conditions, changes in the annealing temperature was 450℃,500℃,550℃,600℃sample preparation. XRD results show that the annealing temperature of 500℃, the samples smaller FWHM, the larger grain size, indicating that the thin films of high quality. PL spectra showed that with the annealing temperature, Cu-doped ZnO thin films of the DL emission is significantly reduced.