Spectroscopic characterization of 4′-substituted aromatic self-assembled monolayers on GaAs(100) surface

A. Shaporenko, K. Adlkofer, L. S.O. Johansson, A. Ulman, M. Grunze, M. Tanaka, M. Zharnikov

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40 Scopus citations

Abstract

High-resolution X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy were applied to characterize GaAs(100) surface engineered by self-assembled monolayers (SAMs) of 4′-substituted aromatic molecules: 4′-methyl-4-mercaptobiphenyl (CH 3-BPT) and 4′-hydroxy-4-mercaptobiphenyl (OH-BPT). Both of these molecules formed ordered and densely packed SAMs on GaAs, which were able to protect the substrate from degradation under ambient conditions. The molecular attachment in the SAMs is mediated by As-thiolate bond while the intact aromatic backbones have an upright orientation with average tilt angles of 31.0° and 37.2° for CH 3-BPT and OH-BPT films, respectively. The difference in the tilt angle is attributed to a higher (by 7-10%) packing density of the former SAM, suggesting that the character of 4′-substitution affects the quality of the resulting SAM on the GaAs substrate.

Original languageEnglish
Pages (from-to)17964-17972
Number of pages9
JournalJournal of Physical Chemistry B
Volume108
Issue number46
DOIs
StatePublished - 18 Nov 2004
Externally publishedYes

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