Research About Fabrication Process And Device Performance Of Linear Pyroelectric Detector

Lithium tantalate（LiTaO₃）has non-linear optical,pyroelectric effect and other performance with development value.It is an important material which are the focus of current research for optical devices,detective devices and other devices.In this paper,the technology of the preparation of lithium tantalate thin film was studed.The lithium tantalate film with good optical and electrical properties was prepared by magnetron sputtering.The effects of different magnetron sputtering processes on the properties of lithium tantalate films were investigated.The effects of different magnetron sputtering power,different substrates,different annealing temperatures and different annealing atmospheres on the performance of lithium tantalate thin films were investigated.The optical parameters of the lithium tantalate film were measured by ellipsometry,and the optical band gap of the films was calculated.At the same time,the polarization process of lithium tantalate film was studied,and the electrical properties such as leakage current,dielectric properties,ferroelectric properties and pyroelectric properties of lithium tantalate film were characterized.The sputtering process were investigated to prepare a good performance film through the detailed characterization of the lithium tantalate film.The thin films annealed at 600°C are closer to the stoichiometric ratio LiTaO₃,but the crystallization performance of the film is poorer than the films annealed at 650oC.To select 600oC or 650oC as the annealing temperature,it depends on the actual situation.The thin films sputtered at 200 W have better crystallization performance,but sputtering at 250 W had a better sputtering rate,and the sputtered lithium tantalate film at 250 W was closer to the（012）preferred single crystal film.Two choices of sputtering power both have a certain research value.The optical parameter was calculated through the ellipsometry characterization.The lithium tantalate film annealed in oxygen at 650oC had the best crystallization performance with a refractive index of 2.33,an extinction coefficient of 0.00234,an optical band gap of 3.66 eV.The electrochemical properties of the lithium tantalate film were studied.The polarization experiment was carried out by using the thermal polarization method.The polarizing process was obtained by several experiments.And the leakage current and ferroelectric properties of the films before and after polarization were compared.After the polarization,the ferroelectric properties of the films were further strengthened,and the remnant polarization was increased by about 5 times to 0.684 μC/cm².The electrical parameters of the films after polarization were also tested.The film leakage current was 1.2 × 10^-7 A,the relative dielectric constant was 14.08,and the dielectric loss was 0.139.The pyroelectric current of the film was also measured.The pyroelectric coefficient of the film is 5.4 nC.cm^-2.K^-1 at 40°C,and finally the above-mentioned electrical parameters are used to calculate the detection value dF and the detection voltage response value vF of 6.705 nC.cm.J^-1 and 93.87 nC.cm.J^-1 respectively.The performance of the lithium tantalate film as the pyroelectric detection unit was characterized by the testing system.When the power of the radiation was 6.9 mW,the radiation frequency was 1.6 Hz,the magnification was 20 pA/V,the maximum voltage value of the device is 0.173 V.So the pyroelectric current generated by the film was 3.46 × 10^-12 A.