Distinguished Lecture Series

Mar 15, 2017, 4:30 PM
Room 86120 (N Center), Sungkyunkwan University, Suwon

Visualization of polarization and screening charges

using atomic force microscopy

Professor Seungbum Hong

Department of Materials Science & Engineering, University KAIST

Abstract

         AFM can detect tiny displacement of the cantilever (< 10 pm) in contact or proximity with the materials surface, and therefore any physical parameters coupled with strain can be used to image relevant order parameters (for example, polarization, magnetization, and ionic concentration). Furthermore, conducting AFM opened up local current measurement in conjunction with external stimuli such as heat and photons, which could be used to detect photovoltaic effect at the nanoscale.

         As imaging consists of positioning, encoding and decoding of measured data and transducing one form of energy into another, any breakthrough in imaging technology can lead to a new design in information storage devices, imaging sensors or energy storage and harvesting devices. Consequently, the inventors of SPM have been deeply involved in innovative probe-based data storage devices (e.g., IBM’s millipede project), where multiple nanoscale tips read and write data on the thin film surface in microelectromechanical system (MEMS).

         The dominant trends of advanced materials characterization using SPM can be characterized by high-resolution, high-speed multi-modal, multi-scale, multi-frequency (band excitation) and resonance enhanced and tracking modes. The keys to success include improvement of spatial and temporal resolution as well as invention of new functional imaging such as scanning resistive probe microscopy with a field effect transistor embedded in the tip or charge gradient microscopy where the electric current induced by the mechanical stimulus can be mapped at high speed. Here in my talk, I will present our recent thrusts on visualization of polarization, screening charges using piezoresponse force microscopy (PFM) and CGM.