Study On PZT Thin Films For Piezoelectric Energy Harvester

With the development of micro-nano process technology?MEMS/NEMS?,the wide application of wireless sensor network nodes and wearable portable microelectronic devices poses new challenges to miniaturization technology.In the current energy harvesting technology research,piezoelectric energy harvesting technology has received extensive attention and research;lead zirconate titanate?PZT?materials are widely used in preparation of an electric energy harvester for their superior dielectric,ferroelectric and piezoelectric properties.Therefore,the key point of developing a more efficient and environmentally applicable piezoelectric vibration energy harvester is the improvement of the performance of the PZT piezoelectric film and the combination of the vibration source design energy collector structure in various environments to improve its output to meet the need for power supply for microelectronics.Based on the research status of PZT piezoelectric film and piezoelectric energy harvester,the performance of PZT piezoelectric film is improved.Different PZT piezoelectric films are prepared by acetic acid regulation and changing the substrate and annealing temperature.The prepared PZT piezoelectric film was characterized.Based on the prepared PZT piezoelectric film,two piezoelectric energy collectors,silicon-based and flexible substrate,were designed and fabricated to meet the energy supply requirements of microelectronic devices in different application environments.PZT sol-gel precursor solution with different acetic acid content was prepared by sol-gel method,and its effect on the structure and properties of the film was studied.The results show that the adjustment of the acetic acid content of the PZT precursor solution can affect the orientation of the PZT?110?crystal orientation,which in turn affects the performance of the PZT piezoelectric film.The PZT piezoelectric film prepared by adding 15 ml of acetic acid?36%?solution in PZT?0.025 mol?precursor solution has the highest?110?crystal orientation degree,and the leakage current is reduced from 1.19×10^-9A to 9.08×10^-10A,the relative dielectric constant reached 1034 at 100Hz,increased by 10%,the hysteresis loop saturation was good,and the residual polarization+Pr increased from 14.1?C/cm² to 17.0?C/cm²,and-Pr from8.1?C/cm² was increased to 11.9?C/cm².Cross-over experiments of different substrates and annealing temperatures were designed based on three different substrates Pt/Ti/SiO₂?TO?/Si,Pt/Ti/SiO₂?PECVD?/Si,Pt/Ti/SiN_x?PECVD?/Si and three different annealing temperatures 550°C,600°C and 650°C.The crystal orientation,morphology and electrical properties of the films were characterized.After comparison:the annealing temperature can adjust the crystal orientation structure of the prepared PZT thin film,and the substrate material can affect the microscopic morphology and surface quality of the PZT thin film,thereby affecting the performance of the PZT thin film.The PZT film on the same substrate material has the best leakage performance at 600°C,and the dielectric properties and ferroelectric properties are improved as the annealing temperature increases.At the same annealing temperature,PZT film based on SiN_x?PECVD?substrate has poor leakage performance,dielectric constant at 550°C:PZT_SiNx?PECVD?>PZT_SiO2?PECVD?>PZT_SiO2?TO?,and the residual polarization is PZT_SiO2?PECVD?>PZT_SiNx?PECVD?at 550?,PZTSiO₂?TO?>PZTSiO₂?PECVD?at 600°C.Based on the research of PZT piezoelectric film,a piezoelectric vibration energy collector of silicon-based double-ended beam was fabricated.The nonlinear vibration characteristics were analyzed theoretically,and the influencing factors of nonlinear vibration characteristics were analyzed by MATLAB.The output characteristics of the silicon-based double-ended beams piezoelectric energy harvester were tested.The test results show that the open-loop output voltage is 33.63mV,the bandwidth is up to 136Hz,the optimal load resistance is 26.9k?,with a power of 51.69nW.The bandwidth is considerable compared to other piezoelectric energy harvesters of the same type.At the same time,the preparation process of the piezoelectric energy harvester of flexible substrate is explored.For the particularity of the flexible substrate,the process is carried out from the perspectives of structural design,silicon-based process parameters,transfer process from silicon substrate to flexible substrate.Explore and experiment,and take a solution to the problem,and realize the transfer of the device structure.