Chemical effects of methyl and methyl ester groups on the nucleation and growth of vapor-deposited aluminum films

A. Hooper, G. L. Fisher, K. Konstadinidis, D. Jung, H. Nguyen, R. Opila, R. W. Collins, N. Winograd, D. L. Allara

Research output: Contribution to journalArticle

132 Scopus citations

Abstract

The interaction of vapor-deposited A1 atoms with self-assembled monolayers (SAMs) of HS(CH2)15CH3 and HS(CH2)15CO2CH3 chemisorbed at Au{111} surfaces was studied using X-ray photoelectron spectroscopy, infrared spectroscopy, time-of-flight secondary ion mass spectrometry, and spectroscopic ellipsometry. For the CH3-terminated SAM, no reaction with C-H or C-C bonds was observed. For total A1 doses up to κ 12 atoms/nm2, penetration the the Au-S interface occurs with no disruption of the average chain conformation and tilt, indicating formation of a highly uniform κ1:1 A1 adlayer on the Au. Subsequently, penetration ceases and a metallic overlayer begins to form at the SAMvacuum interface. These results are explained in terms of an initial dynamic hopping of the S headgroups on the Au lattice, which opens transient diffusion channels to the Au-S interface, and the closing of these channels upon completion of the adlayer. In contrast, A1 atom interactions with the CO2CH3-terminated SAM are restricted to the vacuum interface, where in the initial stages discrete organometallic products form via reaction with the CO2CH3 group. First, a 1:1 complex forms with a reduced C==O bond and an intact CH3 moiety. Further exposure leads to the additional reaction of about four A1 atoms per ester, after which a metallic overlayer nucleates in the form of clusters. After the growth progresses to κ30 Å, the clusters coalesce into a uniform metallic film. These results illustrate the extraordinary degree of control that organic substrates can exert during the course of metal film formation.

Original languageEnglish (US)
Pages (from-to)8052-8064
Number of pages13
JournalJournal of the American Chemical Society
Volume121
Issue number35
DOIs
StatePublished - Sep 8 1999

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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