C60分子在GaAs(001)表面的外延生长的扫描隧道显微镜研究

利用扫描隧道显微镜（STM）系统地研究了C₆₀薄膜在GaAs（001）表面的异质外延生长．在GaAs（001）2×4-β相表面，观察到C₆₀薄膜以非密排面进行生长，并在生长中有结构相变产生．实验数据表明，薄膜下层面心立方（fcc）的晶格常数比C₆₀晶体的晶格常数要大13%；而薄膜的表层结构则展示了非理想的六角密堆（hcp）结构，其表面为hcp（1100）面，生长过程是非理想的层状生长模式．在GaAs（001）-c（4×4）衬底上，C₆₀薄膜的表面仍然是fcc（111）面，其结构参数与C₆₀晶体一致，但C₆₀薄膜采用了三维模式进行生长 关键词：

STUDY ON GROWTH OF C60 MOLECULES ON GaAs(001) SUBSTRATE BY SCANNING TUNNELING MICROSCOPY

We have studied the growth of C₆₀ film on GaAs(001) 2×4-β phase surface epitaxially grown by MBE.Due to the delicate equilibrium between the interaction of C₆₀ molecules and the interaction of C₆₀ molecule with the substrate,the toplayer of C₆₀ film,unlike that on the metal and silicon substrate,shows a non-close packed structure.The facet structure of C₆₀ film exhibits that the top-two layers are hcp but the others are fcc,which implies an existence of the phase-transition from hcp to fcc structure in the film growth.The measurement results that the lattice constant of fcc is 1.13 nm,larger of 13% than that of C₆₀ crystal,and hcp is not ideal which is compressed along c-axis.The strain in C₆₀ film and the minimum of the total energy should be responsible for the existence of the phase-transition.On GaAs(001)-c(4×4) surface,the structure of C₆₀ film shows fcc(111) surface and the film grows in three-dimensional mode which is quite different from that on other substrates.