Template Preparation And Electrical Properties Of NBT Nanotube Structure

One-dimensional ferroelectric materials have wide application prospects in the field of microelectronic devices such as ferroelectric random access memory?Fe RAM?,due to their large specific surface area and directional arrangement.With the development of the concept of green environmental protection and the rapid development of the integration of the microelectronics industry,the preparation and application of one-dimensional lead-free ferroelectric materials have gradually become the focus of scientific attention.Lead-free ferroelectric materials based on sodium bismuth titanate(Na_0.5Bi_0.5Ti O₃,NBT)have better ferroelectric properties and become the first choice to replace lead-containing materials such as lead zirconate titanate?PZT?series.Some researchers have studied the preparation and electrical properties of ferroelectric capacitor based on ferroelectric nanotube array.However,the relationship between the high electrical performance of ferroelectric capacitor and the preparation and micro-electric properties of the nanotube array is still neglected.In this paper,the sol-gel template method is used to prepare a high-quality lead-free NBT nanotube array under the optimized sol filling process.Then,piezoelectric force microscopy?PFM?and conductive atomic force microscopy?CAFM?are used to systematically test the domain state evolution and electrical properties of a single NBT nanotube based on preferred method.Finally,we explore the combination of the etching parameters of nanotube arrays with a certain exposure height,and characterize the effect of different exposure heights on the original domain state and electrical properties of NBT nanotube arrays.We prepare ferroelectric capacitor based on exposed NBT nanotube arrays,test the ferroelectric and piezoelectric properties of ferroelectric capacitors,and use the phase-field theory to simulate the potential distribution of the NBT nanotube and its capacitor structure.The main contents are as follows:1. The sol-gel template method and different sol filling methods are used to prepare different quality NBT nanotube arrays. Compared with the immersion deposition,lower pressure deposition,and spin-coating deposition,the improved method produces NBT nanotube arrays are compatible with a high filling rate,high aspect ratio,uniform wall thickness,and good continuity.2. The single NBT nanotube prepared based on the improved method has a polycrystalline structure and clearly visible lattice stripes.The results from PFM and CAFM show that the better piezoelectric performance of NBT nanotubes is related to its specific domain structure and unique morphology.The stripe domain structure of NBT nanotubes regularly changes under the action of electric field.The presence or absence of an applied electric field will affect the current distribution on the surface of NBT nanotube.3.1.8 mol/L Na OH solution and the etching time for 43 minutes is the preferred parameter combination to obtain NBT nanotube array with suitable exposure height.Compared with the same height of nanotube and template,and nanotube has the phenomenon of aggregation,the nanotube array with an exposure height of 30-55 nm has a clearer regular domain state and better piezoelectric properties.Compared with the horizontal direction,the vertical direction of the nanotube has higher piezoelectric response.4. The electrical performance of NBT nanotube arrays in capacitor structures is tested using a ferroelectric analyzer and PFM.The capacitor structure based on the NBT nanotube array has better ferroelectric and piezoelectric properties than the unplated top electrode.We use the phase-field theory to simulate the potential distribution of the NBT nanotube before and after the top electrode plating.Compared with the unplated top electrode,the potential of the nanotubes in the capacitor structure is uniformly distributed.