Fabrication of the semiconductor superlattice by heteroepitaxy and its related evaluation

(1)以InSb(111)A和InSb(111)B为衬底，采用热清洗和外延生长的方法，在室温下生长出具有2x2重构表面的α - sn薄膜。利用反射高能电子衍射和俄歇电子能谱对生长膜的表面相变进行了研究。对于沸石系统，两种类型的薄膜，每一种都有不同的厚度，分别为8层和30层[ML]，以逐层模式生长，用于检查薄膜的稳定性作为Sn覆盖率的函数。在InSb(111)A上的α - sn薄膜的情况下，8ML和30ML薄膜的表面都不可逆地经历了从已知的3x3结构，到2x2和随后的1x1结构的变化。现在才发现，终于融化了。除熔化外，8ML膜的转变温度比30ML膜高十多度；在150°C时，30ML的薄膜开始从薄膜表面开始融化，随后的融化向薄膜基底界面方向发展，而对于8ML的薄膜，在220°C时，融化迅速发生在整个薄膜上。另一方面，对于α -Sn/InSb(111)B，观察到Sb向Sn膜中的扩散。这种行为与α - sn /InSb(111)A体系的表面相变有很大不同有关。最后，为了讨论α - sn在InSb(111)A上稳定性的可能机制，进行了离散变分x α簇计算。(2)利用Patterson函数、傅里叶分析和最小二乘改进确定了InSb(111)B-(2x2)重构表面的原子结构。所提出的Sb三聚体模型充分解释了透射电子衍射和俄歇电子能谱的实验数据。新结构是Sb-Sb键长为3.14 A的三聚体，以三重对称的方式位于由（2x2）结构组成的底物Sb原子之上。少

(1) Thin films of alpha-Sn were grown of InSb(111)A and InSb(111)B substrates at room temperature, both having 2x2 reconstruction surfaces which were prepared by thermal cleaning and liomoepitaxial growth. Surface phase transition of the as-grown films was investigated by using reflection high energy electron diffraction and Auger electron spectroscopy. For botil systems, two types of the films, each having different thickness of 8 and 30 monolayers[ML], which grew with a layer-by-layer mode, were used to examine the stability of the films as a function of Sn coverage. In the case of the alpha-Sn film on InSb(111)A, the surfaces of both the 8ML and the 30ML films irreversibly underwent from the 3x3 structure as already known, via the 2x2 and subsequently the 1x1 structure which werr. nowly found, finally the melting. The transition temperature for the 8ML film were higher more than ten degrees than those for the 30ML except for the melting ; the 30ML film began to melt from the film su … More rface at 150ﾟC and the subsequent melting progressed toward the filmsubstrate interface, whereas for the 8ML film the melting promptly took place throughout the film at 220ﾟC. on the other hand, for alpha-Sn/InSb(111)B diffusion of Sb into the Sn film was observed. The behavior is related to the fact that the surface phase transition in this system is considerably different from that in the alpha-Sn/InSb(111)A system. Finally, in order to discuss possible mechanism for the stability of alpha-Sn on InSb(111)A, the discrete variational Xalpha cluster calculations were performed.(2) we have used Patterson function, Fourier analysis and least square refinement to determine atomic structures of the InSb(111)B-(2x2)reconstructed surface. The proposed Sb trimer model sufficiently explained the experimental data from transmission electron diffraction and Auger electron spectroscopy. The new structure is that an Sb trimer has the Sb-Sb bond length of 3.14 A and is located with three-fold symmetry above substrate Sb atoms consisting of the (2x2) structure. Less