Simple, robust molecular self-assembly on germanium

We report the facile fabrication of high-quality, robust alkanethiolate self-assembled monolayers (SAMs) on germanium substrates. Our approach to produce SAMs on technologically important substrates takes advantage of the many strategies previously developed for gold-thiol self-assembly. Direct self-assembly of alkanethiols on germanium is impeded by the presence of the native germanium oxide. Using a mixture of water and ethanol, we create an environment where both adsorbate and oxide are sufficiently soluble to enable SAM deposition in a single step. By manipulating reaction conditions, monolayers form spontaneously on untreated germanium, which opens new avenues for the exploitation of self-assembly on semiconductor surfaces. While our analyses initially focused on 1-dodecanethiol on Ge(100), this method is robust and we have extended its use to include a range of adsorbates on Ge(100) as well as to the Ge(111) and Ge(110) substrates.