Self-assembled monolayers of alkyl-thiols on InAs: A Kelvin probe force microscopy study

A. Szwajca, J. Wei, M. I. Schukfeh, M. Tornow

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28 Scopus citations

Abstract

We report on the preparation and characterization of self-assembled monolayers from aliphatic thiols with different chain length and termination on InAs (100) planar surfaces. This included as first step the development and investigation of a thorough chemical InAs surface preparation step using a dedicated bromine/NH4OH-based etching process. Ellipsometry, contact angle measurements and atomic force microscopy (AFM) indicated the formation of smooth, surface conforming monolayers. The molecular tilt angles were obtained as 30 ± 10° with respect to the surface normal. Kelvin probe force microscopy (KPFM) measurements in hand with Parameterized Model number 5 (PM5) calculations of the involved molecular dipoles allowed for an estimation of themolecular packing densities on the surface.Weobtained values of up to n = 1014 cm-2 for the SAMs under study. These are close to what is predicted from a simple geometrical model that would calculate a maximum density of about n = 2.7 × 1014 cm-2. We take this as additional conformation of the substrate smoothness and quality of our InAs-SAM hybrid layer systems.

Original languageEnglish
Pages (from-to)53-59
Number of pages7
JournalSurface Science
Volume633
DOIs
StatePublished - Mar 2015

Keywords

  • InAs
  • Kelvin probe force microscopy
  • Self-assembled monolayers
  • Surface analysis
  • Thiols

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