Correction of cross-talk caused by torsion of cantilever in AFM

Cross-talk effect which always exits in atomic force microscopy(AFM) measurement severely influences the measuring accuracy. The generation mechanism of cross-talk effect was theoretically analyzed and the relationship between deformation of the cantilever and output of position sensitive photo-detecter(PSPD) was established, on which basis a correction method was proposed to eliminate the influence of the cross-talk effect. In the proposed method, AFM system directly obtains the deformation of the cantilever from the output signals. Therefore, the real value of inter-atomic force can be calculated, which is then kept constant in AFM measurement. By using this method, the change of vertical signal resulting from the torsion of the cantilever can be effectively rejected from the total vertical signal detected by the system. Simulation results show that in constant force mode, cross-talk effect has great impact on the measuring results, leading to measuring error and the cross-talk effect caused by tip-sample angle is much greater than that caused by friction. To verify the elimination of cross-talk effect of the proposed method, comparative experiments were performed on a standard sample. Results indicate that the largest range of measuring error decreases from 21.2 nm-32.0 nm to 5.5 nm-10.2 nm after the correction method was applied, which proves that the proposed method can effectively reduce the measuring error caused by cross-talk effect and enhance the measuring accuracy of AFM.