Chaos in Atomic Force Microscopy

Shuiqing Hu, Birck Nanotechnology Center and School of Mechanical Engineering, Purdue University
Arvind Raman, Birck Nanotechnology Center and School of Mechanical Engineering, Purdue University

Abstract

Chaotic oscillations of microcantilever tips in dynamic atomic force microscopy (AFM) are reported and characterized. Systematic experiments performed using a variety of microcantilevers under a wide range of operating conditions indicate that softer AFM microcantilevers bifurcate from periodic to chaotic oscillations near the transition from the noncontact to the tapping regimes. Careful Lyapunov exponent and noise titration calculations of the tip oscillation data confirm their chaotic nature. AFM images taken by scanning the chaotically oscillating tips over the sample show small, but significant metrology errors at the nanoscale due to this ‘‘deterministic’’ uncertainty.