Dynamic-Contact Electrostatic Force Microscopy and its Application to Ferroelectric Domain

Abstract

The detection principle of the “dynamic-contact electrostatic force microscopy (DC-EFM)” with an ac modulation is explained and applications of DC-EFM to the domain structure of ferroelectrics and direct writing on SiO2 insulating layer are presented. DC-EFM utilizes the sustained vibration of the cantilever even in the contact mode operation of the cantilever. The force on the tip in DC-EFM includes the strong repulsive atomic force and the Coulomb interaction between the surface charge density on the sample and the charge on the tip induced by the ac modulation bias applied. The advantages of DC- EFM include that first, one can control the charge on the tip by the ac modulation signal and it is a self-actuating operation, secondly, one can obtain topographic and domain images simultaneously, and finally one can micro- control the surface charge density on the insulating layer by the tip. The observed surface charge density of the TGS single crystal reveals different polarization charge densities depending on the exposed layer. A deterministic domain formation is also observed. The crystallographic defect such as twin boundaries behaves as the natural domain boundary for TGS. Patterns were written on a PZT film by DC-EFM through the domain reversal induced by the bias applied to the tip.