基于MEMS超级电容器的高介电常数CaCu3Ti4O12薄膜制备及电学特性研究

The preparation and electrical properties of CaCu3Ti4O12 films with high dielectric constant based on MEMS supercapacitors

摘要:

相对于电化学超级电容器,静电式电容器具有更高的功率密度和可靠性,但能量密度过低。本文提出制备基于高介电常数薄膜CaCu₃Ti₄O₁₂(CCTO)的高能量密度MEMS静电式超级电容器。首先,以硅片为基底,通过溶胶-凝胶法在不同烧结温度(700℃、800℃、900℃)下制备CCTO薄膜,分别采用X射线衍射仪(XRD)和场发射扫描电镜(FE-SEM)对薄膜的形貌、组分和结晶状况进行表征,发现在800℃烧结温度下CCTO薄膜结晶状况最佳。然后,利用金属-绝缘层-半导体结构测试其I-V和C-V特性,计算得到薄膜的最大阈值电压和能量密度分别为47V和3.2J/cm₃。同时,首次对高介电常数介质膜中存在的介质充电现象进行了研究,并分析了介质充电对静电式超级电容器性能的影响。

Abstract:

Compared to electrochemical supercapacitors, electrostatic supercapacitors have higher power density and reliability, but its energy density are low. In this paper, the MEMS electrostatic supercapacitor with high energy density were prepared based on the high dielectric constant CaCu₃Ti₄O₁₂(CCTO) film. Firstly, CCTO films were synthesized under the different sintering temperatures (700℃, 800℃, 900℃), through a sol-gel method on silicon substrate. The morphology, phase identification and crystalline of CCTO films were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) respectively. The results showed that the CCTO film has the best quality at 800℃. And then, we tested the I-V and C-V characteristics by the metal-insulators-semiconductor capacitor structure, getting the largest hreshold voltage and energy density, which have values of 47 V and 3.2J /cm₃. Meanwhile, the paper firstly proposed to research the phenomenon of dielectric charging in the high dielectric constant film and analyzed the influence on electrostatic supercapacitors.