Macroscale and Nanoscale Photoelectrochemical Behavior of p-Type Si(111) Covered by a Single Layer of Graphene or Hexagonal Boron Nitride

Annelise C. Thompson, Burton H. Simpson, Nathan S. Lewis

Research output: Contribution to journalArticle

Abstract

Two-dimensional (2D) materials may enable a general approach to the introduction of a dipole at a semiconductor surface as well as control over other properties of the double layer at a semiconductor/liquid interface. Vastly different properties can be found in the 2D materials currently studied due in part to the range of the distribution of density-of-states. In this work, the open-circuit voltage (Voc) of p-Si-H, p-Si/Gr (graphene), and p-Si/h-BN (hexagonal boron nitride) in contact with a series of one-electron outer-sphere redox couples was investigated by macroscale measurements as well as by scanning electrochemical cell microscopy (SECCM). The band gaps of Gr and h-BN (0-5.97 eV) encompass the wide range of band gaps for 2D materials, so these interfaces (p-Si/Gr and p-Si/h-BN) serve as useful references to understand the behavior of 2D materials more generally. The value of Voc shifted with respect to the effective potential of the contacting solution, with slopes (ΔVoc/ΔEEff) of -0.27 and -0.38 for p-Si/Gr and p-Si/h-BN, respectively, indicating that band bending at the p-Si/h-BN and p-Si/Gr interfaces responds at least partially to changes in the electrochemical potential of the contacting liquid electrolyte. Additionally, SECCM is shown to be an effective method to interrogate the nanoscale photoelectrochemical behavior of an interface, showing little spatial variance over scales exceeding the grain size of the CVD-grown 2D materials in this work. The measurements demonstrated that the polycrystalline nature of the 2D materials had little effect on the results and confirmed that the macroscale measurements reflected the junction behavior at the nanoscale.

Original languageEnglish
Pages (from-to)11551-11561
Number of pages11
JournalACS Applied Materials and Interfaces
Volume12
Issue number10
DOIs
Publication statusPublished - Mar 11 2020

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Keywords

  • 2D material
  • graphene
  • hexagonal boron nitride
  • photoelectrochemistry
  • scanning electrochemical cell microscopy
  • semiconductor/liquid junction

ASJC Scopus subject areas

  • Materials Science(all)

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