AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Wednesday Sessions
       Session NS+NANO6-WeP

Paper NS+NANO6-WeP9
Formation of Ferroelectric Nano-domains using Scanning Force Microscopy for the Mass Storage System

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: H. Shin, Samsung Advanced Institute of Technology & CRI, Korea
Authors: H. Shin, Samsung Advanced Institute of Technology & CRI, Korea
J.G. Shin, Samsung Advanced Institute of Technology, Korea
S. Hong, Samsung Advanced Institute of Technology, Korea
J.U. Jeon, Samsung Advanced Institute of Technology, Korea
J. Woo, Korea Advanced Institute of Science and Technology
K. No, Korea Advanced Institute of Science and Technology
Correspondent: Click to Email
Applying voltage between the conductive tip in atomic force microscope (AFM) and Pb(Zr,Ti)O@sub 3@ (PZT) films can cause the switching of ferroelectric domains in nanometer scale. Ferroelectric domains (less than 100 nm in diameter) were induced and analyzed. Imaging of ferroelectric domains was achieved by piezoresponse of the PZT films in contact mode of AFM with lock-in amplifier. De-convolution of the first harmonic signal from the lock-in amplifier reveals the details of the formation of nano domains in ferroelectric thin film materials. Formation and imaging of ferroelectric domains in nano size can be applicable to develop the future mass storage system with miniaturization and integration of the AFM through MEMS technology. In this paper, relevant issues, i.e. bit (induced ferroelectric domains) size dependence on poling voltage, pulse width, and film's thickness and microstructure as well as retention characteristics of the induced bits are discussed. In detail, the bit size showed a log-linear dependence on the pulse width and a linear dependence on the pulse voltage. Using the calculation of electric field distribution the size of the induced bits under certain pulse voltage and width was estimated and confirmed by the experiments. As a result it is clear that the thinner films are beneficial to induce smaller and more stable bits under the same poling voltage and pulse width. In addition retention loss phenomena of the induced ferroelectric domains were observed and carefully investigated. The retention loss can be described by an extended exponential decay which implies a narrow distribution of the relaxation times of the domains. Characteristic relaxation time was largely dependent upon poling time, domain size as well as film's microstructures. Finally, an effective way to improve retention failure of the induced ferroelectric domains was proposed and confirmed by experiments.