PREPARATION OF ATOMICALLY SMOOTH GERMANIUM SUBSTRATES FOR INFRARED SPECTROSCOPIC AND SCANNING PROBE MICROSCOPIC CHARACTERIZATION OF ORGANICMONOLAYERS

The suitability of antimony-doped germanium crystals for use as infrar ed attenuated total reflection wave guides and conducting substrates f or scanning tunnelling microscopic imaging of absorbed organic monolay ers has been evaluated. We have used repetitive ion bombardment follow ed by resistive heating of a germanium crystal under ultrahigh vacuum conditions to produce large, atomically flat regions on a Ge(111) crys tal face. Through the combined use of STM, Auger spectroscopy and low- energy electron diffraction, we have demonstrated that monolayer quant ities of tellurium electrochemically deposited onto the Ge surface dra matically reduce the rate of surface oxidation and permit the use of g ermanium crystals as STM substrates in air. The first. STM images acqu ired in air with Ge as the conductive substrate are reported. No degra dation of IR spectral quality occurs when using the Te-covered, Sb-dop ed Ge crystals as ATR elements. These findings suggest that Te-coated, atomically flat, low-resistivity Ge substrates are suitable for both IR spectroscopic and STM imaging of organic monomolecular films.