Unoccupied Electron States and the Formation of Interface between Films of Dimethyl-Substituted Thiophene-Phenylene Coolygomers and Oxidized Silicon Surface

作者：Komolov A S^*; Lazneva E F; Gerasimova N B; Panina Yu A; Zashikhin G D; Pshenichnyuk S A; Borshchev O V; Ponomarenko S A; Handke B

来源：Physics of the Solid State, 2018, 60(5): 1029-1034.

DOI：10.1134/S1063783418050128

The unoccupied electron states and the boundary potential barrier during deposition of ultrathin films of dimethyl-substituted thiophene-phenylene coolygomers of the type of CH3-phenylene-thiophene-thiophene-phenylene-CH3 (CH3-PTTP-CH3) on an oxidized silicon surface have been studied. The electronic characteristics have been measured in the energy range from 5 to 20 eV above the Fermi level using total current spectroscopy (TCS). The structure of the CH3-PTTP-CH3 film surfaces has been studied by atomic force microscopy (AFM), and the atomic compositions of the films have been studied by X-ray photoelectron spectroscopy (XPS). The changes in the maximum intensities measured by the TCS method obtained from the deposited CH3-PTTP-CH3 film and from the substrate during increasing in the organic coating thickness to 6 nm is discussed. The formation of the boundary potential barrier in the n-Si/SiO2/CH3-PTTP-CH3 is accompanied by the decrease in the surface work function from 4.2 +/- 0.1 to 4.0 +/- 0.1 eV as the organic coating thickness increases to 3 nm. The ratio of atomic concentrations C: S in the CH3-PTTP-CH3 films well corresponds to the chemical formula of CH3-PTTP-CH3 molecules. The roughness of the CH3-PTTP-CH3 coating surface was not higher than 10 nm on the similar to 10 x 10 mu m areas as the total CH3-PTTP-CH3-layer thickness was about 100 nm.

• 出版日期2018-5