脉冲激光沉积法制备SrMnO₃薄膜

SrMnO₃ Film Grown by Pulsed Laser Deposition

本文在采用固相反应法的基础上使用两步法制备出了较高纯度单相多晶SrMnO3靶材,并利用脉冲激光沉积法在SrTiO3(001)衬底上使用不同的实验条件尝试制备SrMnO3薄膜。结果表明在较高的衬底温度(≥700℃)和适当的氧压(5 Pa左右)条件下能够生长出结晶性较好的SrMnO3薄膜。本文通过X射线衍射和同步辐射X射线衍射手段确定了SrMnO3薄膜在SrTiO3(001)衬底上的外延生长,其取向关系为SrMnO3(001)//SrTiO3(001)。X射线光电子能谱分析显示薄膜中的Mn元素存在+3价和+4价两种价态,其中大部分为+4价,占所有Mn元素的90%左右。Mn元素+3的价态存在的原因可能是薄膜生长过程中的缺陷以及薄膜中氧空位的存在。薄膜中氧元素的XPS图谱表明氧元素主要以晶格氧的形式存在。XPS图谱中氧元素另一个峰有可能是由于缺陷、吸附氧或氧空位的存在引起的。SrMnO3单相薄膜的制备和测试为对其进一步研究奠定了基础。

Two-step method through solid state reaction is used to synthesize high purity single phase po-lycrystalline SrMnO3 target. Then we use Pulsed Laser Deposition to grow SrMnO3 films on SrTiO3(001) substrates, we have tried different temperatures of substrate and different oxygen pressures during our experiment. Results show that with deposition temperature above 700 de-gree and oxygen pressure around 5 Pa, SrMnO3 film will grow with good crystallinity. X-Ray dif-fraction and synchrotron radiation X-Ray diffraction are measured here to identify the crystal structure. Epitaxy between film and substrate is confirmed and the orientation between film and substrate is SrMnO3(001)//SrTiO3(001), also phi scan shows that at in plane there is no rotation between film and substrate. X-ray photoelectron spectroscopy of Mn element reveal that in the film Mn have +3 and +4 two valence states, about 90 percentage of all the Mn are +4 valence. We speculate that the +3 valence state of Mn comes from defects in film or oxygen vacancy in it. Also XPS of O element is measured, spectroscopy shows that most of O element in film exist as lattice oxygen, another peak in spectroscopy may attribute to defect, absorbed oxygen or oxygen vacancy. Growth of SrMnO3 film establishes foundation for further study of SrMnO3.