SPM IMAGING OF DOMAINS IN PERIODICALLY POLED LiTaO₃ CRYSTALS

ABSTRACT

Periodically poled LiTaO₃ crystals without erosion were characterized by a scanning probe microscope (SPM) using the converse piezoelectric effect. The on-tip force which was controlled by the setpoint value had significant effect on the characterization of domains and domain walls. The piezoresponse (PR) phase and PR amplitude varied with the change of the setpoint value. When the setpoint value was 0 V, the phase difference between neighboring 180° domains reached 180°. The width of domain walls calculated from the PR phase reached the minimum value while that calculated from the PR amplitude reached the maximum at the setpoint value of 0 V. The above minimal and maximal width approached each other at about 400 nm. These phenomena indicate that selecting a moderate on-tip force is very important for the piezoresponse force mode (PFM). PFM can be used to characterize the domain walls that s different from the inner of the domains in physical properties such as piezoelectricity.

Keywords:

• PFM
• periodically poled LiTaO3 crystals
• on-tip force

PACS:

• 81.07.−b
• 77.84.Dy
• 77.80.−e

ACKNOWLEDGMENT

This work was supported by the National Nature Science Foundation under Grant No.90207027 and 90401014, Jiangsu National Science Foundation under Grant No.BK2002410 and BK2004084, and National Key Basic Research and Development Program of China under Grant No.2002CB613303.