Fabrication and Physical Properties of Organic-Inorganic Superlattice

本项目旨在制备和追求有机-无机外延超晶格的新的物理性能。制备方法是范德华外延，它利用分子束外延技术在范德华界面上生长。主要研究结果如下：(1)首次利用KBr-VOPc(钒基酞菁)体系制备了有机-无机外延超晶格。(2)利用原子力显微镜发现，通过改变衬底温度和分子束流密度可以控制生长的有机薄膜的形貌。这一结果对制备原子均匀的超晶格具有重要意义。(3)证明了分子取向可以通过相邻衬底的规则间距来控制。这种方法有望有效地抑制有机-无机超晶格中多域结构的形成，从而降低其结晶度。利用有机-无机超晶格的思想，首次实现了无机材料对有机微结构的封顶。(5)作为有机-无机异质外延的新材料组合，在Se端基的GaAs(111)衬底上引入了金属酞菁，在碱金属卤化物上引入了方酸(C_4H_2O_4)。

This project was aimed at the fabrication and the pursuit of novel physical properties of organic-inorganic epitaxial superlattices. The method of fabrication was van der Waals epitaxy, which utilizes molecular beam epitaxy technique to van der Waals interfaces. The results obtained are as follows : (1) The first example of organic-inorganic EPITAXIAL superlattice has been presented using KBr-VOPc (vanadyl phthalocyanine) system.(2) By using AFM (atomic force microscope), it has been found that the morphology of the grown organic films can be controlled by changing the substrate temperature and molecular beam flux. This result is important to fabricate atomically uniform superlattices.(3) It was demonstrated that the molecular orientation can be controlled by regularly-spaced steps of vicinal substrates. This method is expected to be useful to suppress the formation of multi-domain structure which deteriorates the crystallinity of organic-inorganic superlattices. It will also be useful to fabricate 'quantum wells' , or onedimensionally ordered structure of organic molecules.(4) Capping of organic micro structure by inorganic material for protection is achieved for the first time by using the idea of organic-inorganic superlattice.(5) As new materials combinations for organic-inorganic heteroepitaxy, metal phathalocyanines on Se-terminated GaAs (111) substrates, and squaric acid (C_4H_2O_4) on alkali halides were introduced.