Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 42: Poster: Organic-Inorganic Hybrid Systems and Organic Films
O 42.3: Poster
Tuesday, March 13, 2018, 18:15–20:30, Poster A
Modification of aromatic self-assembled monolayers by electron irradiation: basic processes, related applications, and electric transport properties — Can Yildirim1, Eric Sauter1, Andreas Terfort2, and •Michael Zharnikov1 — 1Applied Physical Chemistry, Heidelberg University, 69120 Heidelberg, Germany — 2Institut für Anorganische und Analytische Chemie, Universität Frankfurt, 60438 Frankfurt, Germany
The effect of electron irradiation on aromatic thiolate self-assembled monolayers (SAMs) with oligophenyl, acene, and oligo(phenylene ethylene) backbones was studied, with emphasis on the basic irradiation-induced processes, performance of these films as negative resists in electron lithography, and electric transport properties. All films exhibited similar behavior upon the irradiation, with clear dominance of cross-linking. The cross-sections for the modification of the SAM matrix, the damage of the SAM-substrate interface, and irradiation-induced cross-linking were derived. Limitations for lithographic applications of these films were considered. The electric transport properties of the SAMs were found to be affected strongly by electric irradiation, with their resistance increasing progressively, by 2-3 orders of magnitude, upon irradiation with doses up to 40 mC/cm2. This increase stemmed predominantly from a change of the contact resistance which, in its turn, was predominantly attributed to progressive irradiation-promoted adsorption of airborne molecules at the SAM-ambient interface. Based on the transition voltage spectroscopy, the behavior of the HOMO-LUMO gap upon irradiation was monitored.