Preparations And Optical Properties Of Zn_1-x Co_xO And Ti_1-xHo_xO₂ Films

In this paper, the Zn_1-xCo_xO and Ti_1-xHo_xO₂ films were prepared by pulsed laser deposition (PLD) technology, using the XeCl excimer laser of 308nm wavelength as the excitation source. The films were deposited on the the single crystal Si (001) substrate in the actively oxygen atmosphere by laser ablating Zn_1-xCo_xO and Ti_1-xHo_xO₂ composite targets. The main content is divided into three parts.First, the excitation circuit and gas parameters of the XeCl excimer laser are optimized by the orthogonal method in this paper.According to the obove simulated date, it is debugged to the experimental device and got an output pulse width 20ns, the output energy of 200mJ and the single pulse laser beam power of 13MW are obtained.Second, the films of ZnO, n(Co):(ZnO)=0.4at%and n(Co):(ZnO)=0.8at% were prepared under the pressure of 30Pa oxygen. The surface morphology, crystal structure and optical properties of ZnO thin film with different doped concentrations were studied. The SEM and XRD results indicate that the crystallinity of films is good, and the crystal is single phase with a high degree of C-axis preferred orientation. Through the analysis of photoluminescence and UV absorption spectroscopy, three emission peaks were found: the UV emission peaks of 398nm, the blue emission peaks of 420nm and 468nm and the green emission peak of 530nm. It is believed that Co ion substitutes Zn ion in the thin films, increasing the concentration of zinc defects, so that the emergence of the blue emission peaks is enhanced and the red shift occurs. Meanwhile the incorporation of Co can effectively control the band gap of the films, and accordingly controls the UV absorption and emission of films.Third, the film of TiO₂, n(Ho):(TiO₂)=0.5at% and n(Ho):(TiO₂)=1.0at% were prepared under the oxygen pressure of 5 Pa. The surface morphology, crystal structure and optical properties of TiO₂ thin films with different doped oncentrations were studied. The XRD and SEM results indicate that the generated crystals are single phases, but the crystallinity of films is not too good. In the study of photoluminescence, the film with the Ho₂O₃ incorporation of 1.0at% exhibits two new peaks of 483nm and 492nm, which is ascribed to that the dopping of Ho into TiO₂ produces two impurity bands, so that the electronics in the bands can be stimulated and emit luminescence.In summary, the metal ions doping can change the crystal structure and optical properties of the films. Meanwhile, the research can also provide some reference data in modifying the physical and chemical properties of films with doping metal ions.