Physical Properties of Endohedral Metallo fullerenes at solid, thin film and nano-scale.

在固体、薄膜和纳米尺度上研究了面内金属富勒烯和高级富勒烯的结构和电子性质。通过同步辐射X射线衍射图的Rietveld精修，确定了M@C&lt；82&gt；(Dy，Ce和Pr)和C&lt；82&gt；的晶体结构为简单立方结构(PA3)。在150K附近观察到M@C&lt；82&gt；晶体的一级结构相变。此外，在C&lt；84&gt；晶体中掺入Rb金属制备了Rb_&lt；8.8(7)&gt；C_&lt；84&gt；，X-射线衍射图显示了PA3的简单立方结构。Rb_&lt；8.8(7)&gt；C_&lt；84&gt；的随温度变化的ESR谱表明，这些化合物不是金属，而是正常的小禁带半导体。由电阻率估算的带隙是光学带隙的1/2。因此，根据电阻率估算的间隙被认为是迁移率…更大的差距。薄膜场效应晶体管(FET)是用M@C&lt；82&gt；、C&lt；82&gt；、C&lt；84&gt；和C&lt；88&gt；制作的。这些FET具有n沟道常导型FET特性。C&lt；88&gt；FET的场效应迁移率达到了~10^&lt；-2&gt；cm^2V^&lt；-1&gt；S，在富勒烯FET中位居第二。多面体金属富勒烯和高富勒烯的常导性源于流经薄膜各个区域的大电流。扫描隧道显微镜(STM)显示了M@C；82&gt；的局域结构的清晰图像，包括内部结构。用扫描隧道显微镜研究了M@C&lt；82&gt；在定义良好的Si(111)-(7×7)表面上的生长，发现M@C&lt；82&gt；第一层中的M@C&lt；82&gt；分子通过C原子之间的化学键和Si吸附原子的悬挂键强烈地结合在Si表面上。第一层以上的M@C；82&gt；分子通过分子间的范德华作用力聚集。通过在200℃下对覆盖有多层M@C；82&gt；的硅衬底进行热处理，形成了M@C&lt；82&gt；的密排结构。利用扫描隧道显微镜针尖的场蒸发，实现了C&lt；60&gt；分子在密堆层中的单分子精确迁移和迁移。从STM尖端进行的针尖拍摄使人们能够绘制由分子大小的空洞组成的纳米级字符、图片和图案。由于工艺简单、可自由控制以及1 nm大小的空洞，该技术广泛适用于纳米级的制造。从而获得了许多关于面内金属富勒烯和高富勒烯的结构和物理性质的信息，并在此基础上尝试了在薄膜FET器件和分子电子学方面的应用。较少

The structures and electronic properties of endohedral metallofullerenes and higher fullerenes have been studied at solid, thin-film and nanometer scale. The crystal structures of M@C_<82>(Dy,Ce and Pr) and C_<82> have been determined to be simple cubic (Pa3) by Rietveld refinements for X-ray diffraction patterns with synchrotron radiation. The first-order structural phase transition was observed for the crystals of M@C_<82> around 150 K. Furthermore, Rb_<8.8(7)>C_<84> was prepared by doping Rb metal into the crystals of C_<84>, and the X-ray diffraction pattern showed the simple cubic structure of Pa3. The temperature-dependent ESR spectra suggested a metallic behavior for Rb_<8.8(7)>C_<84>.The resistivity and optical absorption spectra for M@C_<82>,C_<82> and C_<84> showed that these compound are not metals but normal semiconductors with small gap. The gap estimated from resistivity was 1/2 of the optical gap. Therefore the gap estimated from resistivity was concluded to be mobility … More gap. The thin-film field-effect transistors (FETs) have been fabricated with M@C_<82>,C_<82>,C_<84> and C_<88>. These FETs showed n-channel normally-on FET properties. The field-effect mobility of C_<88> FET reached to 〜10^<-2> cm^2 V^<-1> s^<-1>, whose value was the second highest value among the fullerene FETs. The normally-on properties for endohedral metallofullerens and higher fullerenes originate from high bulk current which flow in all region of thin films.The scanning tunneling microscope(STM) showed clear images of local structures of M@C_<82> inclusive of internal structures. The growth of M@C_<82> on well-defined Si(111)-(7 x 7) surfaces has been fully studied by the STM, and the Stranski-Krastanov type growth was found for M@C_<82>. The M@C_<82> molecules in the first layer are strongly bound on the Si surface through the chemical bond between C atoms and dangling bonds of Si adatoms. The M@C_<82> molecules above the first layer aggregate by van der Waals force between molecules. The close-packed structures of M@C_<82> have been formed by annealing the Si substrates covered with multilayer of M@C_<82> at 200℃.The removals and movements of C_<60> molecules in the close-packed layer of C_<60> have been achieved at single molecular precision by field evaporation with the STM tip. The pin-point shooting from the STM tip enables ones to draw nano-scale characters, pictures and patterns consisting of molecular size voids. Because of technical simplicity, the free controllability, and 1 nm size of voids, this technique is widely applicable to nanoscale manufacture. Thus much information of the structures and physical properties of endohedral metallofullerens and higher fullerenes has been obtained, and the applications towards thin-film FET devices and molecular electronics have been tried based on the obtained information. Less