Fundamentals of CAFM Operation Modes

This chapter discusses the fundamentals of conductive atomic force microscopy (CAFM) operation modes. The focus is on applied studies using commercially available scanning probe microscopes (SPMs) and tips operated primarily in ambient conditions. The chapter starts with an introduction to fundamental tip-sample interactions in contact mode operation, followed by a discussion on alternative operation modes and evaluation techniques. The chapter then provides an overview of fundamental conduction mechanisms and discusses important aspects of the tip-sample system related to the electrical conduction. The currents measured by CAFM depend on the effective emission area (Aeff) through which charge carriers can flow from the tip to the sample. Different authors have addressed the correlation between physical contact area (Ac) and Aeff. The chapter also discusses the tip-sample interaction for the contact mode operation, focusing on the characterization of tunneling currents through thin dielectrics. Finally, it provides some case studies to demonstrate the wide range of CAFM applications.