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

从固体、薄膜和纳米尺度上研究了内嵌金属富勒烯和高级富勒烯的结构和电子性质。用<82><82>Rietveld方法对同步辐射X射线衍射图进行了修正，确定了M@C_（Dy，Ce，Pr）和C_（10）的晶体结构为简单立方（Pa_3）。在150 K附近观察到M@C_晶体的一级结构相变<82>。此外，通过在C_3晶体中掺入金属Rb，制备了Rb_（8.8（7））C_3<84><84>，X射线衍射图显示其为简单立方结构的Pa_3。随温度变化的ESR谱表明Rb_（8.8（7））&gt;C_为金属性质，<84>M@C_，C_和C_的电阻率和光吸收谱<82><82><84>表明这些化合物不是金属，而是正常的小禁带半导体。由电阻率估计的差距为光学间隙的1/2。因此，根据电阻率估计的差距被认为是迁移率 关于我们 间隙用M@C_、C_、C_和C_制作了薄膜场效应晶体管（FET）<82><82><84><88>。这些FET显示出n沟道常开FET特性。C_ FET的场效应迁移率<88>达到了10 ~ 10^<-2>cm ^2 V^<-1>s^<-1>，在富勒烯FET中居第二位。内嵌金属富勒烯和更高级富勒烯的常开特性来源于高的体电流，它流过薄膜的所有区域.扫描隧道显微镜（STM）显示了包括内部结构在内的M@C_2的局部结构的清晰图像<82>.利用STM研究了M@C_<82>在Si（111）-（7 × 7）面上的生长，发现M@ C_的生长为Sttranski-Krastanov型<82>。第一层中的M@C_<82>分子通过C原子间的化学键和Si吸附原子的悬挂键牢固地结合在Si表面上。第一层以上的M@C_<82>分子通过分子间的货车范德华力聚集。在<82>200℃下对覆盖有多层M@ C_的Si衬底进行退火，形成了M@ C_<82>的密堆积结构，利用STM针尖场蒸发技术，实现了<60>C_密堆积层中C_分子的<60>单分子精确去除和运动。从STM针尖的针点射击使人们能够绘制纳米级的字符，图片和图案组成的分子大小的空隙。由于技术简单，自由可控性，和1纳米尺寸的空隙，这种技术是广泛适用于纳米制造。因此，许多信息的结构和物理性质的内嵌金属富勒烯和更高的富勒烯已经获得，并在薄膜场效应管器件和分子电子学的应用已经尝试基于所获得的信息。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