Preparation and Characterization of Periodically Poled Ferroelectric Lithium Niobate (LiNbO 3 )
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1255-M02-05
Preparation and Characterization of Periodically Poled Ferroelectric Lithium Niobate (LiNbO3) Zhengzheng Zhang,1 Camelia N. Borca,2 D. Wu,3 Alexei Gruverman,1 Orhan Kizikaya,4 Jie Xiao1 and Peter A. Dowben1 1 Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln NE 68588, USA 2 Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen, Switzerland 3 Department of Chemistry, Duke University, Box 90354, Durham, NC 27708-0354, USA 4 The J.Bennett Johnston Sr. Center for Advnanced Microstructures and Devices, Louisiana State University, Baton Rouge, LA, USA ABSTRACT No compositional variations of periodically poled lithium niobate (PPLN) (period of ~28 µm) are found using spatially resolved near edge X-ray adsorption fine structure (XANES) spectra taken at the Nb K-edge. The periodicity the ferroelectric domain patterns can be imaged using piezoresponse force microscopy (PFM) and atomic force microscopy (AFM) and the periodic variations in the optical properties of PPLN result in a nonlinear optical response in the IR region at a fixed scattering angle. INTRODUCTION One of the characteristic features of the ferroelectric is the presence of electrically reversible polarization. In a properly oriented ferroelectric sample, such as LiNbO3 crystal thin film, the polarization can be aligned perpendicular to the surface in the positive or negative direction to form antiparallel ferroelectric domains. A domain wall separates these two domain states. The distinctly oriented domains differ in the sign of key non-vanishing components of the piezoelectric, electro-optic, and nonlinear optical tensor., many devices can be fabricated in these materials. Consequently, A variety of poling techniques have been developed [1] providing considerable control of the ferroelectric domain structures. Here, we describe some of the properties of periodically poled lithium niobate (PPLN). PERIODICALLY POLED LITHIUM NIOBATE In our experiment, periodically poled lithium niobate (PPLN) substrates of congruent composition (Crystal Technologies) have been used as ferroelectric templates. At room temperature, lithium niobate exhibits a hexagonal symmetry with polarization along the c axis (polar axis) which allows only two possible domain orientations. The samples used in this study were 5 x 5 x 0.5 mm3 plane-parallel plates cut normal to the polar axis. A periodic domain pattern (period of ~28 µm) was been fabricated by depositing a photoresist mask on the +c sample face and applying a voltage of 10 kV through a fixture with an electrolyte solution. The mask was been removed after poling
the lithium niobate by means of chemical-mechanical polishing, leaving behind a bare ferroelectric surface of lithium niobate. As a result, periodic domain patterns containing stripes of antiparallel 1800 domains, with their dipoles oriented either positive or negative along the surface normal have been produced (figure 1a). These domain patterns have been observed in ambient envi
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