Hydrogermylation of alkenes and alkynes on hydride-terminated Ge(100) surfaces

Covalently bonded organic monolayers on semiconductor surfaces are potentially important for the fabrication of novel electronic devices and sensors. In contrast to the recent interest in and development of methods for monolayer formation on silicon surfaces, only one wet chemical route has been previously published for germanium surfaces. We present novel strategies to prepare organic monolayers on hydride-terminated Ge(100) surfaces utilizing the available Ge-H bonds as chemical handles. The new hydride-terminated Ge(100) surface was prepared by utilizing an efficient preparation method involving soaking in an aqueous 10% HF solution. Lewis acid mediated hydrogermylation of alkynes and alkenes on the hydride-terminated Ge(100) surfaces results in alkenyl and alkyl surfaces, respectively, bound through Ge-C bonds. Thermal treatment of hydride-terminated Ge surface with neat alkenes and alkynes, or solutions in mesitylene, also results in similar organic monolayers. Finally, these two approaches were contrasted with UV photoinduced hydrogermylation of alkenes. The resulting organic monolayers were characterized by infrared spectroscopy (ATR-FTIR), stability studies, and contact angle measurements.