Observation of Hydrogen-Terminated Silicon (111) Surface by Ultrahigh-Vacuum Atomic Force Microscopy

Si(111) surface terminated with hydrogen by NH 4 F treatment was observed with an ultrahigh-vacuum atomic force microscope (UHV-AFM). Monoatomic steps, triangular etch pits and contamination islands were imaged. Atomically resolved images were also obtained and the periodicity in these images is in good agreement with the Si(111):H-1×1 (monohydride) structure. The corrugation amplitude is 0.10-0.12 nm, which is much larger than any STM result. This value is in fairly good agreement with the value expected in the contact hard sphere model.