ON THE ROUGHNESS OF PERFECTLY FLAT H-SI(111) SURFACES AN ATOMIC-FORCEMICROSCOPY APPROACH

Perfectly flat H-Si(111) surfaces are investigated by atomic force mic roscopy. The influence of both doping level and etching time on the su rface morphology is studied through a statistical quantitative approac h based on the power spectral density of the topography. Irrespective of the etching time, moderately p-doped and all n-type samples exhibit atomically flat surfaces, whereas etching of p+ wafers leads to a dra stically different roughness rapidly increasing with time. This behavi our is explained by a random electrochemical etching mechanism that is added to the sterically limited chemical mechanism. (C) 1998 Elsevier Science B.V. All rights reserved.