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Title: Growth of pentacene on clean and modified gold surfaces

Abstract

The growth and evolution of pentacene films on gold substrates have been studied. By combining complementary techniques including scanning tunneling microscopy, atomic force microscopy, scanning electron microscopy, near-edge x-ray-absorption fine structure, and x-ray diffraction, the molecular orientation, crystalline structure, and morphology of the organic films were characterized as a function of film thickness and growth parameters (temperature and rate) for different gold substrates ranging from Au(111) single crystals to polycrystalline gold. Moreover, the influence of precoating the various gold substrates with self-assembled monolayers (SAM's) of organothiols with different chemical terminations has been studied. On bare gold the growth of pentacene films is characterized by a pronounced dewetting while the molecular orientation within the resulting crystalline three-dimensional islands depends distinctly on the roughness and cleanliness of the substrate surface. After completion of the first wetting layer where molecules adopt a planar orientation parallel to the surface the molecules continue to grow in a tilted fashion: on Au(111) the long molecular axis is oriented parallel to the surface while on polycrystalline gold it is upstanding oriented and thus parallels the crystalline orientation of pentacene films grown on SiO{sub 2}. On SAM pretreated gold substrates the formation of a wetting layer is effectivelymore » suppressed and pentacene grows in a quasi-layer-by-layer fashion with an upstanding orientation leading to rather smooth films. The latter growth mode is observed independently of the chemical termination of the SAM's and the roughness of the gold substrate. Possible reasons for the different growth mechanism as well as consequences for the assignment of spectroscopic data of thin pentacene film are discussed.« less

Authors:
; ;  [1]
  1. Physikalische Chemie I, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)
Publication Date:
OSTI Identifier:
20976714
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 75; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevB.75.085309; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; ATOMIC FORCE MICROSCOPY; COATINGS; GOLD; LAYERS; ORGANIC SEMICONDUCTORS; PENTACENE; ROUGHNESS; SCANNING ELECTRON MICROSCOPY; SCANNING TUNNELING MICROSCOPY; SILICA; SILICON OXIDES; SUBSTRATES; SURFACE TREATMENTS; SURFACES; THIN FILMS; THREE-DIMENSIONAL CALCULATIONS; X RADIATION; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY

Citation Formats

Kaefer, Daniel, Ruppel, Lars, and Witte, Gregor. Growth of pentacene on clean and modified gold surfaces. United States: N. p., 2007. Web. doi:10.1103/PHYSREVB.75.085309.
Kaefer, Daniel, Ruppel, Lars, & Witte, Gregor. Growth of pentacene on clean and modified gold surfaces. United States. doi:10.1103/PHYSREVB.75.085309.
Kaefer, Daniel, Ruppel, Lars, and Witte, Gregor. Thu . "Growth of pentacene on clean and modified gold surfaces". United States. doi:10.1103/PHYSREVB.75.085309.
@article{osti_20976714,
title = {Growth of pentacene on clean and modified gold surfaces},
author = {Kaefer, Daniel and Ruppel, Lars and Witte, Gregor},
abstractNote = {The growth and evolution of pentacene films on gold substrates have been studied. By combining complementary techniques including scanning tunneling microscopy, atomic force microscopy, scanning electron microscopy, near-edge x-ray-absorption fine structure, and x-ray diffraction, the molecular orientation, crystalline structure, and morphology of the organic films were characterized as a function of film thickness and growth parameters (temperature and rate) for different gold substrates ranging from Au(111) single crystals to polycrystalline gold. Moreover, the influence of precoating the various gold substrates with self-assembled monolayers (SAM's) of organothiols with different chemical terminations has been studied. On bare gold the growth of pentacene films is characterized by a pronounced dewetting while the molecular orientation within the resulting crystalline three-dimensional islands depends distinctly on the roughness and cleanliness of the substrate surface. After completion of the first wetting layer where molecules adopt a planar orientation parallel to the surface the molecules continue to grow in a tilted fashion: on Au(111) the long molecular axis is oriented parallel to the surface while on polycrystalline gold it is upstanding oriented and thus parallels the crystalline orientation of pentacene films grown on SiO{sub 2}. On SAM pretreated gold substrates the formation of a wetting layer is effectively suppressed and pentacene grows in a quasi-layer-by-layer fashion with an upstanding orientation leading to rather smooth films. The latter growth mode is observed independently of the chemical termination of the SAM's and the roughness of the gold substrate. Possible reasons for the different growth mechanism as well as consequences for the assignment of spectroscopic data of thin pentacene film are discussed.},
doi = {10.1103/PHYSREVB.75.085309},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 8,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}