| Domain structure and its movement determine the physical properties of ferroelectrics. Investigation of domains is the precondition to study macroscopic properties of ferroelectrics. There are many methods to investigate domains, such as polarization microscopy, scanning electron microscopy, transmission electron microscopy, scanning electron acoustic microscopy and so on. However, these methods suffer from some serious disadvantages involving complex sample preparation, damage to sample, low resolution. Scanning Force Microscopy (SFM), which roots from atomic force microscopy, is a general designation of microscopy relating to force behavoir technology. Because of its simple operation, high resolution without the need for special sample preparation, SFM is paid great attention in all scientific fields. SFM is an effective method to study domains with high resolution and nondestructive measuring. This paper studies the investigation methods of domain using voltage-modulated SFM. Different principles and modes of SFM are discussed. The imaging principle of piezoresponse atomic force microscopy, scanning nonlinear dielectric microscopy, Kelvin force microscopy are theoretically analysed, and the influence of voltage, contact force and microcantilever on the domain investigation is studied. The parameters of instrument are optimized using the same sample. And the result is that the domain structure of PMN-PT can be achieved successfully using DF3-R microcantilever when Vac≥3V, f=5-20kHz. Different cantilevers and electric fields are studied respectively in order to weaken and even eliminate the effect of electrostatic force. The results show that the influence of electrostatic can be diminished effectively when using cantilever with high spring coefficient.The work provides not only the foundation of studying domain structure in ferroelectric thin films but also the means of studying fatigue and polarization retention in ferroelctrics... |
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