LIMM: a Technique for Determination of the Spatial Distribution of the Spontaneous Polarization in Ferroelectric Thin Films

摘要

The Laser Intensity Modulation Method (LIMM) is used to determine the spatial distribution of polarization in the direction of the polar axis of a ferroelectric sample. It is based upon measurement of the pyroelectric current generated by the material when it is heated with a laser beam which is intensity-modulated over a range of frequencies. A modification of this technique has been developed which will permit detailed profiling of the polarization distribution in a thin-film electroded ferroelectric layer on a substrate, such as a ferroelectric memory. The theory of the technique is discussed and it is shown that the determination of the polarization distributions requires the solution of a Fredholm integral equation of the 1st kind using experimental data. A novel method of solution of this problem using neural networks is described.