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Dynamical Observations of MBE Grown Thin Films by Ultrahigh Vacuum In-situ Electron Microscopy

超高真空原位电子显微镜对 MBE 生长薄膜的动态观察

基本信息

批准号：
63550543
负责人：
OSAKA Toshiaki
金额：
$ 1.41万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

We have studied homoepitaxial growth processes and surface reconstruction of InSb{111} using ultrahigh vacuum in-situ transmission electron microscopy (UHV in-situ TEM) combined with UHV in-situ reflection electron microscopy (REM). From the TEN observations for InSb(111)B and the REM observations for both reconstructed InSb(111)A and reconstructed InSb(111)B surfaces, the following results were obtained:(1) When the incident fluxes(1:1) of Sb_4 and In_1 are impinged onto the InSb(111)B substrate, the respective molecules form homoepitaxially grown InSb films, leaving an excess molecule Sb^* which does not contribute to the formation of the InSb films. As a result, there exists a critical temperature(T_h) for the condensation of Sb^* molecules. Below T_h, the surface concentration of Sb^*(n_<sb*>) becomes higher than a critical concentration for the condensation (n^c_), SO that two phases (InSb+Sb) grow in a polycrystalline state. However, above T_h as n_<sb*> becomes lower than n^c_, InSb films grow with the 2x2 reconstructed surfaces. This critical temperature is defined as a homoepitaxial temperature. Quantitative interpretations of T_h were discussed.(2) By using UHV in-situ REM, changes in the surface reconstructions of InSb(111)B and InSb(111) A were for the first time observed: for (111)B from the 2x2-Sb to the 3xl-In structure at 420ﾟC and for (111)A from the 2x6-Sb to the 2x2-In structure at 300ﾟC. The particles formed on the InSb(111)B and (111)A surface at 420ﾟC and 450ﾟC respectively, intensely affected the structural transformation in the InSb(111) surface. Also, the particle formed on the InSb(111)B-3xl-In substrate played an important role in spreading the (111)B-3x3-In region which appeared during the homoepitaxial growth of InSb(111)B.

利用超高真空原位透射电镜（UHV原位TEM）和超高压原位反射电镜（REM）研究了InSb{111}的同外延生长过程和表面重建。通过对InSb(111)B表面的TEN观测和重构InSb(111)A和重构InSb(111)B表面的REM观测，得到以下结果：(1)当Sb_4和In_1以1:1的入射通量撞击InSb(111)B衬底时，各自的分子形成同外延生长的InSb薄膜，留下多余的Sb^*分子，这对InSb薄膜的形成没有贡献。结果表明，存在Sb^*分子缩聚的临界温度（T_h）。在T_h以下，Sb^*(n_< Sb *>)的表面浓度高于冷凝的临界浓度（n^c_），使得两相（InSb+Sb）以多晶状态生长。然而，在T_h以上，当n_<sb*>小于n^c_时，InSb薄膜随着2x2重构表面生长。这个临界温度被定义为同外延温度。讨论了T_h的定量解释。(2)通过超高压原位REM，首次观察到InSb(111)B和InSb(111) A的表面重构变化：（111）B在420 C时由2x2-Sb变为3x1 - in结构，（111）A在300 C时由2x6-Sb变为2x2-In结构。在420和450℃的温度下，InSb(111)B和（111）A表面形成的颗粒对InSb(111)B表面的结构转变有强烈的影响。InSb(111)B- 3x3- in衬底上形成的颗粒对InSb(111)B (111)B-3x3- in区在InSb(111)B的同外延生长过程中扩散起重要作用。