Domain Structure Study Of Lithium Niobate Superlattice Using Microwave Impedance Microscope

Lithium niobate superlattice with superior piezoelectric, pyroelectric and optical properties, is widely used in acoustics, integrating acoustics, integrated optical and acoustic surface wave device. In recent years, a new kind of Scanning Near-field Microwave Microscope called Microwave Impedance Microscope (MIM) has been developed based on commercial Atomic Force Microscope (AFM), which can detect various types of samples’surface electricial properties, mapping sample’s surface topography and complex dielectric constant with high resolution and high sensitivity simultaneously. This outstanding ability makes MIM an ideal tool for interdisciplinary research.This thesis is divided into four chapters:The first chapter is mainly about the literature review of lithium niobate crystals and microwave near-field microscopy.An overview of the structure of lithium niobate, physical properties and as well as give an overview of the development and application. Summarizes the development history of microwave near-field microscopy as well as its theoretical basis.The second chapter firstly introduces the lithium niobate superlattice structure principle and development of the application.Then analyzes the polarization properties of lithium niobate crystals from room temperature polarization domain dynamics. Provides theoretical basis for room temperature polarization technology for the preparation of lithium niobate superlattice.Finally we introduced a method using photolithography, magnetron sputtering, encapsulation and room temperature polarization process successfully prepared two dimensional lithium niobate superlattice, the cycle of lithium niobate superlattice is 12 microns.In the third chapter, we introduced a new type of near-field microwave microscope called microwave impedance microscope which designed by laikeji from Stanford university in USA. We analyze the advantages and disadvantages between the traditional microwave near-field microscopye and microwave impandance microscope by studying aspects of its experimental principle and equipment structure of them.At the same time we studied measuring principle of observing lithium niobate superlattice using microwave impedance microscope and deduced a series of results could be observed.Success in the end, we using microwave impedance microscope observed two-dimensional domain structure of lithium niobate superlattice, and analyzes its electrical properties, and expect the same results were obtained.We also use COMSOL simulation analysis the potential distribution near the tip when using microwave impedance microscope observating lithium niobate superlattice.We deduced the relationship of electrical conductivity of lithium niobate superlattice between the real and image part of microwave impedance microscope signal.The fourth chapter summarizes the paper’s main work and prospect the future development of this field.