The Effect of Surface Inclination on AFM Force-Curve Calibration and Evaluation

The aim of the work is the investigation of the effect of surface inclination and tip-surface interactions on the calibration and evaluation of AFM (atomic force microscopy) force-curves. For this purpose, both ideally flat and hard samples (Si wafer) and inclined but equally hard samples were used to measure the deflection inverse optical lever sensitivity, or InvOLS, of the cantilever. The inclined samples were polydimethylsiloxane (PDMS) irradiated and hardened by a proton beam to around 22 GPa, in a way, that the irradiated area forms a hill with inclination angles between 10-15°. It is demonstrated that surface inclination can cause a ±10 % deviation in the obtained lever sensitivities, which in turn can cause even a cause a - 30 % to +50 % relative error in the obtained elastic modulus for the surfaces, if neglected during force-curve evaluation.