Growth Mechanism And Physical Properties Analysis Of Compound Oxide Thin Film

Pulsed laser deposition（PLD） is one of the rising technologies for the preparation of thin films in laboratories. Because it can maintain the stoichiometry of the target after deposition. In addition, there are some advantages including fast deposition rate, short experimental period and low substrate temperature. We can adjust the substrate temperature, laser energy, laser frequency, oxygen pressure etc. to fabricate the films under the proper conditions. Apart from the advantages mentioned above, the good compatibility, easily cleaning and the various kinds of materials lead to its extensive use. So, it makes sense to explore the effects on the oxide thin films prepared under different process conditions.Here, we mainly focus on the following issues: 1. the growth of copper and copper oxide thin films on STO（001） substrate under the different conditions. 2. the growth of the SMO:Ni O compound thin films on different substrates.Firstly, we mainly studied the effects of substrate temperature, laser energy and frequency on crystal structure, surface morphology, electrical properties, optical properties, chemical valence states etc during the copper oxide thin film fabrication. We have drawn the phase diagram of Cu, Cu₂ O, Cu:Cu₂O thin films from mass of experimental results. The results indicate that Cu film would be got under high substrate temperature and low laser energy density, on the contrary, the Cu₂ O film or the composite film will be preparation under low substrate temperature and high laser energy density. According to the measurements, the Cu₂ O film kept the semiconductor properties with a rough surface under the high substrate temperature and laser energy density. Compared with the pure Cu₂ O film, the composite Cu: Cu₂ O thin film exhibited higher light absorption coefficients in the ultraviolet and infrared regions. By the XPS and XAES analysis, we confirmed that only Cu⁰ and Cu¹⁺ ions were in the films and the chemical valence states could be adjusted by choosing growth conditions.Secondly, we mainly discussed the fabrications of cubic Sr Mn O₃ and Sr Mn O₃:Ni O thin films on different substrates. The results showed that the growth on different substrates should be in different conditions:when the films prepared on STO（001）, YAO（001）, YAO（010） substrates, the oxygen pressure is 5 Pa, however, the pressure should be as low as 1*10^-5Pa, when the films were grown on the STO（111）. We expected to turn SMO from AFM-PE state to FM-FE state by applying strain at room temperature, but there are still some challenges. We have successfully modulated the VAN structure by changing the volume ratio of SMO and Ni O. The room temperature FM state was achieved successfully. Further explorations and experiments were needed for achieving the FE state.In conclusion, we have explored the growth mechanisms of pulse laser deposition. To fabricate films of different chemical valence and crystal structure, it was necessary to change the deposition conditions, substrates, volume ratio of target materials and so on. The physical properties of films were also studied.