磁控溅射钽酸锂薄膜工艺与热释电性能研究

发布时间：2018-07-05 12:34

本文选题：钽酸锂 + 磁控溅射　；参考：《电子科技大学》2017年硕士论文

【摘要】：钽酸锂(LiTaO_3)具有非线性光学,热释电效应等具有研发价值的性能。其作为光学器件、探测器件等器件的重要材料是当前研究的重点。课题中对磁控溅射制备钽酸锂薄膜的工艺及薄膜的光学、电学性能进行了重点研究,使用磁控溅射工艺制备了具有良好光学及电学性能的钽酸锂薄膜。研究了不同磁控溅射工艺对钽酸锂薄膜性能的影响。重点研究了不同射频磁控溅射功率、衬底、退火温度和退火气氛对钽酸锂薄膜性能的影响。通过椭偏仪测试了钽酸锂薄膜的各项光学参数,计算出了薄膜的光学禁带宽度。研究了钽酸锂薄膜的极化工艺,并对极化后的薄膜的介电性能,铁电性能以及热释电性能进行了表征。最终,搭建热释电探测平台,测试了钽酸锂薄膜作为敏感元的探测器的热释电响应电流。通过对钽酸锂薄膜的详细表征,确定了能够制备良好性能薄膜的溅射工艺。600oC时退火薄膜的Li含量高,但是结晶性能没有650oC好,选择600oC及650oC度退火,薄膜各有优劣。200 W时溅射的薄膜的晶体性能较好,但是溅射速率没有250W时快,250 W功率下溅射的钽酸锂薄膜更接近(012)择优取向的单晶薄膜。这两种功率下溅射的薄膜都具有一定的研究价值。使用椭偏仪测试了薄膜的光学参数。测试了具有最好的晶体性能的钽酸锂薄膜的光学参数:折射率为2.33、消光系数为0.00234、光学禁带宽度为3.66 eV。研究了钽酸锂薄膜的电学性能,使用热极化法对钽酸锂薄膜进行了极化实验,通过多次实验得到了较好的极化工艺。并对极化前及极化后的薄膜的漏电流,铁电性能进行了比较。发现极化过后,薄膜的铁电性能进一步加强,剩余极化比自发极化提高了5倍,达到0.684μC/cm~2。测试了取得良好极化后薄膜的电学参数。薄膜漏电流为1.2×10~(-7) A,相对介电常数为14.08,介电损耗为0.139。搭建平台对薄膜的热释电电流进行了测量。薄膜在40oC时热释电系数为5.4 nC.cm~(-2).K~(-1),最终使用上面的电学参数对探测优值及探测电压响应值进行了计算,dF为6.705nC.cm.J~(-1),其vF为93.87 nC.cm.J~(-1)。搭建测试平台对钽酸锂薄膜作为热释电探测单元的性能进行了测试,在黑体辐射下的功率为6.9 mW时,经过斩波,频率为1.6 Hz,放大倍数为20 pA/V时,示波器显示器件最大电压差为0.173 V,得到薄膜产生的热释电电流为3.46×10~(-12) A。
[Abstract]:Lithium tantalate (LiTaO _ 3) has many properties, such as nonlinear optics, pyroelectric effect and so on. As an important material of optical devices, detectors and other devices, it is the focus of current research. The optical and electrical properties of lithium tantalate thin films prepared by magnetron sputtering were studied. The lithium tantalate thin films with good optical and electrical properties were prepared by magnetron sputtering. The effects of different magnetron sputtering processes on the properties of lithium tantalate thin films were investigated. The effects of RF magnetron sputtering power, substrate, annealing temperature and annealing atmosphere on the properties of lithium tantalate thin films were investigated. The optical parameters of lithium tantalate film were measured by ellipsometry, and the optical band gap was calculated. The polarization process of lithium tantalate thin films was studied. The dielectric properties, ferroelectric properties and pyroelectric properties of the films were characterized. Finally, the pyroelectric response current of the detector using lithium tantalate thin film as the sensor was measured. Through the detailed characterization of lithium tantalate thin films, it was determined that the Li content of the annealed films was high when the sputtering technology was. 600oC, but the crystallinity was not as good as 650oC, and 600 OC and 650 OC degree annealing was chosen. The crystal properties of the thin films deposited at 200 W are better, but the lithium tantalate films sputtering at 250 W power at a sputtering rate of less than 250 W are closer to the (012) preferred orientation single crystal thin films. The thin films deposited under these two kinds of power have some research value. The optical parameters of the films were measured by ellipsometry. The optical parameters of the lithium tantalate thin film with the best crystal properties are as follows: refractive index is 2.33, extinction coefficient is 0.00234, and optical band gap is 3.66 EV. The electrical properties of lithium tantalate thin films were studied. The polarization experiments of lithium tantalate thin films were carried out by means of thermal polarization, and a better polarization process was obtained through many experiments. The leakage current and ferroelectric properties of the films before and after polarization were compared. It is found that after polarization, the ferroelectric properties of the films are further enhanced, and the residual polarization is 5 times higher than that of spontaneous polarization, reaching 0.684 渭 C / cm ~ (2). The electrical parameters of well polarized films were measured. The leakage current is 1.2 脳 10 ~ (-7) A, the relative dielectric constant is 14.08, and the dielectric loss is 0.139. A platform was built to measure the pyroelectric current of the film. The pyroelectric coefficient of the film is 5.4 nC.cm-2. K-1 at 40oC. Finally, using the above electrical parameters, the detection excellent value and the detection voltage response value are calculated, and the VF is 93.87 nC.cm.J-1, and the detection voltage response value is 6.705nC.cm.J-1. The performance of lithium tantalate thin film as pyroelectric detection unit was tested by using a test platform. When the power of the film was 6.9 MW under blackbody radiation, the frequency was 1.6 Hz and the amplification was 20 Pa / V after chopping. The maximum voltage difference of the oscilloscope display device is 0.173 V, and the pyroelectric current generated by the film is 3.46 脳 10 ~ (-12) A.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O484

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