Rahe Philipp
Fachbereich Physik, Universität Osnabrück, Barbarastrasse 7, 49076 Osnabrück, Germany.
Beilstein J Nanotechnol. 2020 Oct 26;11:1615-1622. doi: 10.3762/bjnano.11.144. eCollection 2020.
Thin insulating films are commonly employed for the electronic decoupling of molecules as they enable a preservation of the intrinsic molecular electronic functionality. Here, the molecular properties of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) adsorbed on insulating CaF thin films that were grown on Si(111) surfaces are studied. Scanning tunnelling microscopy is used to compare the properties of PTCDA molecules adsorbed on a partly CaF-covered Si(111) surface with deposition on thicker CaF/CaF/Si(111) films. The identification of mostly single molecules on the CaF/Si(111) interface layer is explained by the presence of atomic-size defects within this layer. Geometry-optimisation calculations using density functional theory reveal a geometry on CaF(111) of nearly flat-lying PTCDA molecules with two oxygen atoms displaced towards calcium surface ions. This geometry is in agreement with the experimental observations.
薄绝缘膜通常用于分子的电子去耦，因为它们能够保留分子固有的电子功能。在此，研究了吸附在生长于Si(111)表面的绝缘CaF薄膜上的3,4,9,10-苝四羧酸二酐（PTCDA）的分子性质。使用扫描隧道显微镜比较吸附在部分覆盖CaF的Si(111)表面上的PTCDA分子与沉积在较厚CaF/CaF/Si(111)薄膜上的PTCDA分子的性质。CaF/Si(111)界面层上主要为单分子的鉴定可通过该层内存在原子尺寸的缺陷来解释。使用密度泛函理论进行的几何优化计算揭示了在CaF(111)上PTCDA分子近乎平躺的几何结构，其中两个氧原子向钙表面离子方向位移。这种几何结构与实验观察结果一致。
