分子团簇负离子束沉积超薄BiSe二维拓扑绝缘体

项目名称： 分子团簇负离子束沉积超薄BiSe二维拓扑绝缘体

项目编号： No.11205116

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 物理学II

项目作者： 刘雍

作者单位： 武汉大学

项目金额： 30万元

中文摘要： 本项目发展适用于二维超薄材料制备的分子团簇负离子束技术，用串列加速器的铯溅射负离子源产生BiSe,FeSe和BiFeSe等化合物离子束，在两个45度分析磁铁之间安装电扫描装置，团簇离子束靶室中的样品台外接负偏压使离子减速，获得能量1-10keV的化合物离子束，在Si(111)和GaAs(111)表面形成超薄BiSx薄膜。用原子力显微镜、扫描电镜、高分辨透射电镜和掠入射X射线衍射等方法测定薄层的形貌、结构和缺陷特性，用Hall效应测定薄膜的电阻率、载流子浓度和迁移率。改变团簇离子能量、剂量、退火温度等参数，系统研究制备工艺对BiSe超薄层的结构和物理性质的影响，获得优化的制备工艺条件。通过精确控制团簇离子剂量，制备3-7nm厚的拓扑绝缘体薄膜。用离子-固体相互作用理论、晶体生长理论等探讨超薄层形成的物理机制，为分子团簇离子束制备二维纳米材料提供科学依据。

中文关键词： 铋铁硒；拓扑绝缘体；穆斯堡尔谱；价态；磁性

英文摘要： This project develops molecular cluster ion beam technology for preparation of two-dimensional ultrathin materials. Molecular ion beams of BiSe and BiFeSe will be generated by using a celsium sputtering negative ion source equipped on a tandetron accelerator. An electric scanner will be installed between the two 45-degree analytical magnets, and the sample stage in the cluster beam chamber will be biased with a negative voltage to decelerate the ion beams to 1-10 keV. Ultrathin films of BiSe films will be formed on Si(111)and GaAs(111) by using the low-energy cluster beams. The morphology, structure, and defects will be measured by atomic force microscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and grazing-incidence X-ray diffraction, and their resistivity, carrier concentration and mobility will be studied by Hall effect. The preparation process will be optimized by tuning the ion beam energy, dose, and process temperature, with a goal of preparing 3-7 nm thick toplogical insulators. The formation of the ultrathin layers will be interpreted by cluster-solid interaction and crystal growth theories, to lay a foundation for development of the molecular cluster beam technology in preparation of novel low-dimensional materials.

英文关键词： BiFeSe；topological insulator；Mossbauer effect；valence state；magnetization