Fabrication of novel functional surfaces through ionic crystal / semiconductor heterostructurse and their properties

对目前的研究成果进行了总结。(1)电子能谱研究Mg和Ba薄膜的初始氧化过程mgo和BaO与GaAs和Si晶格匹配，有望成为功能钙钛矿氧化物与高度发达的半导体技术相结合的关键材料。本文利用俄歇能谱、电子能量损失能谱和紫外光电子能谱揭示了Mg和Ba薄膜的初始氧化过程。澄清了氧化的条件，如临界氧暴露，适当的衬底温度等。利用反射高能电子衍射（RHEED）对碱卤化物异质结构界面进行了分析。这种方法的缺点是探测电子会对生长的薄膜造成损害。在本工作中，我们利用微通道板（MCP）设计了高灵敏度的RHEED应用程序，可以将探测电流降低1/8000。利用该装置可以观察到卤化碱薄膜的初始生长过程，并详细地阐明了卤化碱薄膜的生长机理。(3)在GaAs（001）上构建具有两层碱卤化物缓冲层的复杂异质结构，在GaAs（001）上生长出具有岩盐氧化膜的单晶MgO膜。与在GaAs上直接生长相比，MgO的生长温度降低到150℃（001）。生长膜的电子能量损失谱与体MgO的电子能量损失谱吻合较好，表明表面化学计量保持不变。在超高压条件下，该结构在高达600ºC的温度下保持稳定。复杂异质结构的概念将有助于在GaAs衬底上制造功能氧化物层，并导致氧化物/半导体集成器件。(4)碱卤化物/半导体异质结构的光产率测量我们设计了一种新的仪器来测量薄膜表面的光产率。目前已经测量了不同NaCl厚度的NaCl/GaAs异质结构的光产率。这提供了电子发射的光阈值和外来异质结构（如NaCl/GaAs）的能带对准的附加信息。少

The results of the present research are summarized.(1) Initial oxidation process of Mg and Ba films studied by electron spectroscopiesMgO and BaO, which are lattice matched to GaAs and Si, could be expected to be key materials to integrate functional perovskite oxides with highly developed semiconductor technologies. In the present work we have revealed the initial oxidation process of Mg and Ba films using Auger electron spectroscopy, electron energy loss spectroscopy and ultraviolet photoelectron spectroscopy. The conditions of oxidation such as critical oxygen exposure, appropriate substrate temperature, etc. have been clarified.(2) Evaluation of alkali halide hetero-interface by high sensitive RHEED analysisThe interface of alkali halide heterostructures have been analyzed by reflection high energy electron diffraction (RHEED). The disadvantage of this method is that the probing electron causes damage to the growing film. In the present work we have devised high sensitive RHEED app … More aratus using micro channel plate (MCP), which could reduce the probing current by as much as 1/8000. With this apparatus we could observe the initial growth process of alkali halide films and clarified the mechanism in detail.(3) A complex heterostructure to achieve a rocksalt oxide film on GaAsA single-crystalline MgO film was grown on GaAs(001) by constructing a complex heterostructure with two alkali halide buffer layers. The growth temperature was decreased to 150 ﾟC as compared with direct growth of MgO on GaAs(001). Electron energy loss spectrum of the grown film agreed well with that of bulk MgO, indicating that surface stoichiometry was maintained. The structure was stable up to 600ﾟC against heating in UHV condition. The concept of a complex heterostructure will help fabrication of functional oxide layers on GaAs substrates and lead to oxide/semiconductor integrated devices.(4) Photoyield measurement of alkali halide/semiconductor heterostructureWe have devised a new apparatus to measure a photoyield from the film surface. The photoyield from the NaCl/GaAs heterostructure with various NaCl thickness have been measured up to now. This provides the photo threshold for the electron emission and additive information on the band alignment of the exotic heterostructure such as NaCl/GaAs. Less