Effect of Electric Fields on Silicon-Based Monolayers

Tiexin Li, Chandramalika Peiris, Essam M. Dief, Melanie MacGregor, Simone Ciampi, Nadim Darwish

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Electric fields can induce bond breaking and bond forming, catalyze chemical reactions on surfaces, and change the structure of self-assembled monolayers on electrode surfaces. Here, we study the effect of electric fields supplied either by an electrochemical potential or by conducting atomic force microscopy (C-AFM) on Si-based monolayers. We report that typical monolayers on silicon undergo partial desorption followed by the oxidation of the underneath silicon at +1.5 V vs Ag/AgCl. The monolayer loses 28% of its surface coverage and 55% of its electron transfer rate constant (ket) when +1.5 V electrochemical potential is applied on the Si surface for 10 min. Similarly, a bias voltage of +5 V applied by C-AFM induces complete desorption of the monolayer at specific sites accompanied by an average oxide growth of 2.6 nm when the duration of the bias applied is 8 min. Current-voltage plots progressively change from rectifying, typical of metal-semiconductor junctions, to insulating as the oxide grows. These results define the stability of Si-based organic monolayers toward electric fields and have implication in the design of silicon-based monolayers, molecular electronics devices, and on the interpretation of charge-transfer kinetics across them.

Original languageEnglish
Pages (from-to)2986-2992
Number of pages7
JournalLangmuir
Volume38
Issue number9
DOIs
Publication statusPublished - 8 Mar 2022

Keywords

  • electric fields
  • silicon-based monolayers
  • Si-based monolayers
  • C-AFM
  • Atomic force microscopy
  • silicon
  • charge-transfer

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