In Situ Study The Surface Of SrTiO₃ Single Crystal And The Growth Of SrRuO₃ Thin Film On SrTiO₃

ABO3 perovskite oxide materials have many characteristics such as variety of the species and various properties, causing many scholars interested in the study of type of ABO3 perovskite oxide materials. Strontium titanate(STO) is a cubic perovskite structure of dielectric and ferroelectric, which has good dielectric properties, thermal stability, low loss and dielectric regulatory. Especially its lattice constant is 3.905 (?), which has good lattice matching for many single crystalline oxides, so it is widely used as thin film substrate. This thesis mainly studies the surface electronic structure and the changes of chemical composition of STO single crystal after annealed in vacuum. Using scanning electron microscope (SEM) to study the characterization of surface topography. Basing on the study of strontium titanate, we grow SrRuCO3 thin films on srtontium titanate substrate using pulsed laser deposition. We use in situ synchrotron radiation photoelectron spectroscopy to study the electronic structure of SrRuO3thin films, and use SEM to characterize of surface topography. This thesis mainly research results are as follows:1. We treat the Nb:STO crystal samples with UHV annealing, and using in situ Synchronization Radiation Photoemission Spectroscopy to study the electronic structure, and using scanning electron microscope (SEM) characterization of the surface appearance. We found that when Nb doped STO crystal sample is annealed in UHV at 700 ℃, the adsorption impurities such as carbon and hydroxyl on the surface of the STO single crystal could be removed, to expose the fresh intrinsic surface with a constant ratio of Ti/O. It is obvious that the STO would be doped by Ca+ impurities of bulks and O vacancies in surface after annealing at 920℃ for one hour. According to the SEM image data we find that the STO crystal sample which was annealed at 700 ℃ has certain influences. We observe some stripes of fuzzy morphology on the image.2. Basing on our study earlier, we grow the SRO thin film with the STO crystal as a substrate with PLD. For the SRO thin film, using in situ Synchronization Radiation Photoemission Spectroscopy we study the electronic structure, and using SEM to characterize the surface appearance. According to our study, we found that the growth of thin films are insulation, as the difference of oxygen flux, and all the SRO films have different chemical composition, accompanied with the surface defects. Analysis of the valence band spectra, it is interesting that the O2p and Ru4d band is completely separated. Increasing the oxygen pressure, the Ru4d band shape is changed, the O2p peak also has a tendency to be raised, and the valence band spectra shape become more and more close to the real SRO film valence band spectra shape. Through the analysis of the image data of SEM and EDX, with increasing the oxygen flux, we found that film did not become more smooth in the macro level, the composition of SRO films had no obvious change. In conclusion, the conditions for the SRO film growth still require a lot of research works.