Nano boyutlardaki yüzeylerin Q kontrolü altında atomik kuvvet mikroskobu kullanarak taranmasının sayısal simülasyonu

In this thesis, we investigate nano scanning in tapping mode atomic force microscopy (AFM) under quality (Q) control via numerical simulations performed in SIMULINK. We focus on the simulation of whole scan process rather than the interactions between the AFM probe and the surface only. This enables us to quantify the scan performance under Q control for different scan variables and settings. We first demonstrate the trade-off in setting the effective Q factor (Qeff) of a cantilever probe in standard Q control. Low values of Qeff causes an increase in tapping forces while higher ones limit the maximum achievable scan speed due to the slow response of the cantilever to the rapid changes in surface profile. We then show that it is possible to achieve higher scan speeds without causing an increase in the tapping forces using adaptive Q control (AQC), in which the Q factor of cantilever is changed instantaneously depending on the magnitude of error signal in oscillation amplitude. The scan performance of AQC is quantitatively compared to that of standard Q control using iso-error curves obtained through numerical simulations first and then validated through scan experiments performed in a physical set-up.