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

(1)用电子能谱研究了镁、钡薄膜的初始氧化过程。与砷化镓和硅晶格匹配的氧化镁和氧化钡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。在本工作中，我们用俄歇电子能谱、电子能量损失谱和紫外光电子能谱揭示了镁和钡薄膜的初始氧化过程。(2)用高灵敏度RHEED分析评价碱卤化物异质界面。利用反射高能电子衍射(RHEED)对碱卤化物异质界面进行了分析。这种方法的缺点是探测电子会对生长的薄膜造成破坏。在目前的工作中，我们设计了高灵敏度的RHEED应用程序…更多的Aratus使用微通道板(MCP)，可以将探测电流降低多达1/8000。利用该装置可以观察到碱卤化物膜的初始生长过程，并详细地阐明了其生长机理。(3)采用复合异质结的方法在GaAs(001)衬底上生长了单晶氧化镁薄膜。与在(001)衬底上直接生长氧化镁相比，生长温度降低到150ﾟC。生长的薄膜的电子能量损失谱与体相氧化镁的电子能量损失谱吻合较好，表明薄膜的表面化学计量比保持不变。在超高压条件下，结构稳定在600ﾟC以下。复合异质结的概念将有助于在GaAs衬底上制备功能氧化层，并导致氧化物/半导体集成器件。(4)碱卤化物/半导体异质结的光产额测量我们设计了一种新的装置来测量薄膜表面的光产额。到目前为止，已经测量了不同厚度的氯化钠/砷化镓异质结的光产额。这为电子发射提供了光阈值，并提供了关于奇异异质结构(如NaC l/GaAs)的带排列的附加信息。较少

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