The Study Of Photoluminescence Properties Of Pr³⁺ Doped SrTiO₃ And CaTiO₃ Thin Films Prepared By PLD Method

ZnO films, a directly wide band gap semiconductor, has gained substantial interest because of its large exiton binding energy (60meV), which could lead to lasing action based exiton recombination even above room temperature. It have been actively studied because of its potential applications. 1D nanostruture material of ZnO such as aligned nanowires, nanobelts, nanorings and nanohelixes are discovered one after another in recent years. Owing to their unique photic, electrical, and magnetic properties, they have greatly attracted material scientists attentions. 1D ZnO nanostruturesbased devices like nanogenerators, field effect transistors, sensors, solar cells are p redicted to be effective solutions to the problems of energy, environment, biology, electronics, photoelectricity, spaces and so on. Specially, the studies for ZnO semiconductors have now attracted much attention of many researchers. To research the effects of different deposition pressure on the structure and optical properties of ZnO films, in this paper, we prepared ZnO films with different deposition pressure(0.5Pa-5.0Pa) by radio frequency (RF) magnetron sputtering. Surface morphology, crystal structure, optical and magnetic properties of ZnO based films were investigated by XRD, SEM, ultraviolet-visible spectrum photometer et al.and studied the characteristics and optical properties.The results are the following:1. ZnO films were prepared by the radio frequency magnetron sputtering technique (RF) on Si(111) and quartz glass substrates. The effect of different deposition pressure on the structural and optical properties of ZnO films and ZnO films under 25%N₂ were discussed in details. X-ray diffraction (XRD) pattern and SEM indicates that the films are single phase and had wurtzite structure with c-axis orientation under an acceptable deposition pressure(＞2.0Pa). The SEM shows that the grain size of ZnO films increases with the increasing of deposition pressure and then decreases. The crystallation of samples were promoted with the increasing of deposition pressure and then become difference, With increasing of deposition pressure, lattice constant of ZnO films which calculated also increases and (002) diffraction peak position of ZnO films becomes smaller.In the study of transmittance spectra of the ZnO films, We find the transmittance spectra of the ZnO films are higher than 80% in the visible light range. The absorption edges are determined to be around 380nm, the corresponding optical band gaps increasing with the deposition pressure increasing, are about 3.23ev-3.27ev. There is no much differents between Transparency spectra and PL spectra of ZnO thin films with different deposition pressure because we think all optical properties are come from the effects of electromagnetic radiation in electrons. After compared with ZnO thin films and ZnO thin films under 25%N₂ , There is no much difference in the structural and optical properties between them. So we think when we used N₂ as a doped source, N³⁺ didn't doped into ZnO because it didn't actived, so it's very hard to form N doped ZnO thin films with effective concentration.2. The effect of different deposition pressure on the structural properties of Zn_0.975Cu_0.025O films under 25%N₂ were compared with ZnO thin films under 25%N₂ in details. Zn_0.975Cu_0.025O films under different deposition pressure grows with the c-axis(002) diffraction peak orientation. Cu doped enhanced the preferred orientation of c-axis of Zn_0.975Cu_0.025O films under 25%N₂. After compared with Zn_0.975Cu_0.025O thin films and ZnO thin films under 25%N₂, Zn_0.975Cu_0.025O films with 4.0Pa deposition pressure have the biggest diffraction peak, the biggest grain size and the smallest FWMH. But ZnO thin films under 25%N₂ with 2.0Pa deposition pressure have the biggest diffraction peak, the biggest grain size and the smallest FWMH. C-axis lattice constant of Zn_0.975Cu_0.025O films is bigger than ZnO thin films, so compress stress in Zn_0.975Cu_0.025O films perpendicular to the c-axis is bigger. With the increase of deposition pressure, sheet particles in Zn_0.975Cu_0.025O films under N₂ are decrease and spherical particles are increased at the same time. With Cu doped, The preferred orientation of c-axis of Zn_0.975Cu_0.025O films is more obvious, grain size decreased and spherical particles are increased. The density of films is increased and the thickness of Zn_0.975Cu_0.025O films are also influenced. When we used N₂ as doped sourced, there is N-Cu pairs in Zn_0.975Cu_0.025O films, so it's hard to form N doped ZnO thin films with effective concentration.