Functionalization of undoped and p-doped Si (100) using atomic force microscope tips in the presence of propan-2-ol, butan-2-ol and toluene

Abstract

A technique, based on amplitude modulation of Atomic Force Microscope (AFM) tips, in the absence of an applied bias voltage, is reported in this study. Under ambient humidity conditions, ultra-sharp n-doped silicon tips (spike radius ~1nm) oscillating at 160–250kHz generate raised nanostructures ~50–200nm wide and ~2nm high on undoped or p-doped Si (100) surfaces pretreated with certain neat organic solvents. The solvents in the present work are propan-2-ol, butan-2-ol, or toluene. AFM is used to characterize the nanostructures which are found to be stable for at least 96h. It is suggested that mechanical stress associated with the oscillatory Hookean energy (~5–15eV) of the tip promotes cleavage of residual solvent bonds on the surface. This bond cleavage, and the presence of surface defects, which may be critical in the formation of surface-solvent bonds (specifically Si–O–C or Si–C) to create the observed nanostructures, is discussed. The process described here to create raised nanostructures is distinctly different from all other reported techniques to date.