Self-assembly of a 1-eicosanethiolate layer on InSb(100)

Yissel Contreras, Anthony J. Muscat

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

1-Eicosanethiolate molecules form relatively weak bonds with the surface of InSb(100) limiting the order of the self-assembled monolayer despite the long length of the alkyl chain. Heating to only 225 °C in vacuum completely desorbed the eicosanethiolate layer from the surface based on X-ray photoelectron spectroscopy. Even after deposition times as long as 20 h in ethanol, the asymmetric methylene stretch was at 2925 cm -1 in the attenuated total reflection Fourier transform infrared spectrum, which is indicative of alkane chains that are incompletely ordered. Atomic force microscopy images combined with ellipsometry showed that the eicosanethiolate layer conformed to the rough InSb(100) starting surface (2.3 ± 0.2 nm RMS). The reoxidation kinetics in air of InSb(100) and InSb(111)B covered with eicosanethiolate layers was the same despite the lower surface roughness of the latter (0.64 ± 0.14 nm). The bond that the S head group makes with the substrate is the primary factor that determines the cohesiveness of the molecules on the surface. Although interactions between the alkane chains in the layer are sufficient to form a self-assembled layer, the fluidity of the molecules in the layer compromised the chemical passivation of the surface resulting in reoxidation in air after 20 min.

Original languageEnglish (US)
Pages (from-to)67-75
Number of pages9
JournalApplied Surface Science
Volume370
DOIs
StatePublished - May 1 2016

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Keywords

  • Eicosanethiol
  • InSb(100)
  • Liquid phase
  • Passivation
  • Self-assembly

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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