Electrodeposition of nanosized germanium from GeBr4 and GeCl4 in an ionic liquid

Germanium films several micrometers in thickness were electrodeposited for the first time at room temperature from the ionic liquid 1-butyl-3-methyliinidazolium hexafluorophosphate, saturated with either GeBr4 or GeCl4.. Cyclic voltammograms of both systems are similar and exhibit two apparently irreversible diffusion-controlled reduction peaks. The more positive first process is correlated to the Ge(IV)/Ge(II) redox couple, the second process to Ge(II)/Ge(0). The initial stages of the overpotential deposition start with the formation of nanoclusters in both systems, shown with in situ scanning tunneling microscopy, Qualitative X-ray photoelectron spectroscopy analysis shows that the micrometer thick black bulk deposits composed of nanoclusters contain mostly elemental germanium with a small amount of bromide or chloride at the surface, respectively. (C) 2002 The Electrochemical Society.