Noncontact Scanning Nonlinear Dielectric Microscopy Research Articles

Simultaneous Observation of Surface Morphology and Dielectric Properties Using Non-Contact Scanning Nonlinear Dielectric Microscopy with Atomic Resolution

ABSTRACTRecently, we have developed Non-Contact Scanning Nonlinear Dielectric Microscopy (NC-SNDM) with a new height-control technique utilizing higher order nonlinear dielectric constant detection (ε(4) signal). In theoretically, NC-SNDM has quite high height sensitivity against the gap between tip and sample as well as STM technique and the simultaneous observation of the topography and ferroelectric polarization (local dipole moment) distribution with atomic resolution has been expected. To confirm such performance of NC-SNDM with atomic resolution, UHV-SNDM was developed and Si(111) cleaned surface was chosen as a specimen. As a result, we have succeeded in observing Si(111) 7×7 atomic structure. Moreover, distribution of tunneling current and lowest order nonlinear dielectric signal ε(3) could be observed simultaneously. To the best our knowledge, this is the first successful demonstration of the atomic resolution achievement in dielectric microscopy techniques.

Non-contact scanning nonlinear dielectric microscopy

Contact-type scanning nonlinear dielectric microscopy (SNDM) can measure thedistribution of linear and nonlinear dielectric properties of insulators with sub-nanometreresolution. SNDM, however, has a tip-abrasion problem, and this problem is one of theobstacles in obtaining a high-quality image.In this paper, in order to improve SNDM, we propose a non-contact scanning nonlineardielectric microscopy (NC-SNDM) which focuses on the nonlinear dielectric signal forcontrolling the non-contact condition. With the NC-SNDM technique, topographic andSNDM images were obtained successfully. Moreover, from the calculation results, it wasconfirmed that NC-SNDM has atomic-order sensitivity to the gap between the tip and thespecimen.