Orientation Control of Organic Conductor Thin Films by Magnetic Field

尽管分子电子器件的发展需要有机导体薄膜的良好取向，但有机导体薄膜的取向控制还没有实现。有机薄膜的结构分析困难是获得取向良好的有机导电薄膜的瓶颈之一。在这项研究中，我们用X射线衍射法精确地测定了BEDT-TTf、在KCl(001)NaC l和KBr(001)衬底上形成的外延薄膜的面内取向。用新研制的X射线衍射仪研究了外延有机薄膜的面内晶体取向。有机材料是在真空中沉积在KCl、NaC l和KBr3种衬底上的。用X射线衍射仪对得到的薄膜进行了分析。Theta/2thata对称性扫描表明，薄膜中的BEDT-TTf晶体以(10-2)BEDT-TTf//(001)KCl的关系取向。利用该信息，搜索包含面内取向信息的03-2不对称反射，作为法向到基片表面的旋转角(φ)的函数(图1)。因此，成功地测量了03-2反射。从衍射矢的测量方向确定了BEDT-TTf与KCl衬底的平面外延关系为&lt；211&gt；_&lt；BEDT-TTF&gt；//&lt；110&gt；_&lt；KCl&gt；研究了磁场对有机薄膜面内取向的影响。

Although well-oriented thin films of organic conductors are demanded for progress in molecular electronic devices, the orientation control of thin films of organic conductors have not been accomplished. The difficulty in the structural analysis of organic thin films is one of the bottlenecks to obtain the well-oriented organic conducting thin films. In this study, we have precisely determined the in-plane orientations of the epitaxial thin films of BEDT-TTF, perylene and p-sexiphenyl formed on the KCl (001) NaCl, and KBr (001) by using X-ray diffraction. In-plane crystal orientations of eptaxial organic thin films were investigated using a newly developed X-ray diffractometer. Organic materials was deposited onto KCl, NaCl and KBr substrates in vacuum. The obtained thin films were analyzed by using the X-ray difrractometer. The theta/2thata symmetry scan suggested that BEDT-TTF crystals in the thin films oriented in the relation of (10-2) BEDT-TTF // (001) KCl. Using this information, 03-2 asymmetry reflections that include the information of the in-plane orientations were searched as a function of rotation angle (φ) of a normal vector to the substrate surface (Fig.1). Consequently, the 03-2 reflections were successfully measured. From the measured directions of the diffraction vectors, it was determined that the in-plane epitaxial relationship of BEDT-TTF and KCl substrate is <211>_<BEDT-TTF> // <110>_<KCl>. The effects of magnetic filed on in-plane orientation of organic films were also examined.