Preparation of atomically smooth Ge substrates for combined IR spectroscopy and scanning probe microscopy of organic monolayers

Academic Article


  • Germanium (Ge) is a widely used substrate for ATR infrared spectroscopy of monolayer films due to its hydrophilic surface and favorable optical properties. Low resistivity, Sb-doped Ge is also a semiconductor, and has the potential to act as a conductive substrate for scanning probe microscopy applications. We have investigated whether large ATR crystals of Ge can be made atomically flat and resistant to atmospheric oxidation, thus enabling us to use them simultaneously as an IR-transparent ATR waveguide and a scanning probe conducting substrate. A protocol has been developed for producing atomically flat Ge substrates resistant to oxidation; this method involves UHV annealing and the electrochemical deposition of a well-ordered, passivating atomic layer of tellurium (Te) onto the Ge surface in order to eliminate further re-oxidation of the clean, ordered, Ge substrate. We have obtained STM images in air of the Ge:Te surface and found no sign of disordered oxide formation. IR spectroscopy of monolayer films transferred onto the Sb-doped Ge crystal show little difference with spectra obtained from normal, monocrystalline Ge ATR crystals.
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    Author List

  • Gregory BW; Stephens S; Dluhy RA; Thomas S; Stickney J; Bottomley LA
  • Start Page

  • 486
  • End Page

  • 487
  • Volume

  • 2089