Silicon growth at the two-dimensional limit on Ag(111)

Andrew J. Mannix, Brian Kiraly, Brandon L. Fisher, Mark C Hersam, Nathan P. Guisinger

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Having fueled the microelectronics industry for over 50 years, silicon is arguably the most studied and influential semiconductor. With the recent emergence of two-dimensional (2D) materials (e.g., graphene, MoS2, phosphorene, etc.), it is natural to contemplate the behavior of Si in the 2D limit. Guided by atomic-scale studies utilizing ultrahigh vacuum (UHV), scanning tunneling microscopy (STM), and spectroscopy (STS), we have investigated the 2D limits of Si growth on Ag(111). In contrast to previous reports of a distinct sp2-bonded silicene allotrope, we observe the evolution of apparent surface alloys (ordered 2D silicon-Ag surface phases), which culminate in the precipitation of crystalline, sp3-bonded Si(111) nanosheets. These nanosheets are capped with a √3 honeycomb phase that is isostructural to a √3 honeycomb-chained-trimer (HCT) reconstruction of Ag on Si(111). Further investigations reveal evidence for silicon intermixing with the Ag(111) substrate followed by surface precipitation of crystalline, sp 3-bonded silicon nanosheets. These conclusions are corroborated by ex situ atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Even at the 2D limit, scanning tunneling spectroscopy shows that the sp3-bonded silicon nanosheets exhibit semiconducting electronic properties.

Original languageEnglish
Pages (from-to)7538-7547
Number of pages10
JournalACS Nano
Issue number7
Publication statusPublished - Jul 22 2014



  • molecular beam epitaxy
  • scanning tunneling microscopy
  • silicene
  • surface reconstruction
  • two-dimensional materials

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

Cite this

Mannix, A. J., Kiraly, B., Fisher, B. L., Hersam, M. C., & Guisinger, N. P. (2014). Silicon growth at the two-dimensional limit on Ag(111). ACS Nano, 8(7), 7538-7547.