PASSIVATION OF SI(111)-7X7 BY A C-60 MONOLAYER

C-60 monolayers are formed on a Si(111)-7X7 surface under ultrahigh va cuum (UHV) conditions. The effects of exposure to atmosphere (for 30 m in) and water (for 30 s) are assessed by comparing images of the surfa ce acquired using an UHV scanning tunneling microscope. Following expo sure and/or immersion we are able to resolve the C-60 molecules exhibi ting hexagonal order in an arrangement which is essentially identical to that formed prior to withdrawal from the UHV system. Our results cl early show that deposition of one monolayer of C-60 on a Si surface ca n inhibit chemical attack by water and atmospheric oxygen. (C) 1996 Am erican Institute of Physics.