CCTO高介电薄膜的制备及其介电性能研究
发布时间：2018-08-31 20:31
【摘要】：本文通过高分子辅助沉积法,在铜、金和铂等金属基底以及铝酸镧单晶基底上尝试制备CaCu3Ti4O12(CCTO)薄膜,通过对制备工艺的不断调整与优化,分别制备出了成膜均匀、质量较高的多晶和外延CCTO薄膜,对薄膜进行介电性能测试,结果表明制得的CCTO薄膜的介电常数较大,而介电损耗也非常大,直接阻碍了高介电材料CCTO在电子器件中的应用,为更准确探究CCTO内部介电损耗的本质,本文主要探寻两种有效的方法可以降低损耗:1,在一定的高压范围,高纯氧条件下,通过高分子辅助沉积法制备CCTO薄膜。通过控制一定压强的纯氧,可大幅减少微观结构内的氧空位缺陷,继而降低其介电损耗,但压强大过固定阈值时,薄膜与基片间存在的晶格失配、热膨胀不匹配,以及气压压强等因素,将导致晶胞体积发生较大改变,继而引发一系列的位错、缺陷、畴界和晶格畸变,这些变化又会引发新的空间电荷,使低频段的介电损耗骤增。当高压处于0.35~0.75Mpa,气氛为高纯氧(99.999%)时,在单晶基底LaAlO3(LAO)(001)上制备得到的CCTO的介电损耗为0.002~0.01(10-100kHz),当气压为0.55Mpa时,介电损耗最低,损耗角正切值tanδ≈0.002(10-100kHz)。2,通过对CCTO薄膜进行锆掺杂,高压下掺杂烧结,薄膜的介电损耗先增大后减小。常压下掺杂烧结,CCTO的介电损耗先减小后增大。不同气压和不同掺杂量,Zr离子堆积的主要位置也不相同,一部分进入晶界,阻碍自由电子移动,减小漏电流,增大了晶界的绝缘性,降低损耗,另一部分进入晶粒,取代Ti离子,导致TiO6八面体结构更加失衡、不对称,介电损耗大幅增大,气压条件与掺杂改性共同决定了,Zr离子的主要堆积位置,继而对CCTO薄膜介电损耗产生不同影响,结果表明,常压下5%-10%的掺杂量下,CCTO薄膜的介电损耗得到了最大改善,损耗角正切值tanδ≈0.001-0.006(10-100kHz)。
[Abstract]:In this paper, CaCu3Ti4O12 (CCTO) thin films were prepared on copper, gold and platinum substrates and lanthanum aluminate single crystal substrates by polymer assisted deposition. The dielectric properties of high quality polycrystalline and epitaxial CCTO films are tested. The results show that the dielectric constant of the prepared CCTO films is large and the dielectric loss is very large, which directly hinders the application of high dielectric material CCTO in electronic devices. In order to explore more accurately the nature of dielectric loss in CCTO, two effective methods are explored in this paper to reduce the loss: 1, and to prepare CCTO thin films by macromolecule assisted deposition under certain high pressure and high pure oxygen conditions. By controlling the pure oxygen at a certain pressure, the oxygen vacancy defects in the microstructure can be greatly reduced, and then the dielectric loss can be reduced. However, when the pressure exceeds the fixed threshold, the lattice mismatch between the film and the substrate exists and the thermal expansion does not match. Factors such as pressure and pressure will lead to a great change of cell volume, which will lead to a series of dislocations, defects, domain boundaries and lattice distortions. These changes will lead to new space charges, resulting in a sudden increase in dielectric loss at low frequency. The dielectric loss of CCTO prepared on single crystal substrate LaAlO3 (LAO) (001 is 0.002 ~ 0. 01 (10-100kHz) when the high pressure is 0.35 ~ 0. 75 MPA and the atmosphere is high purity oxygen (99. 999%). When the pressure is 0.55Mpa, the dielectric loss is the lowest, and the loss angle tangent value tan 未 鈮，
本文编号：2216078
[Abstract]:In this paper, CaCu3Ti4O12 (CCTO) thin films were prepared on copper, gold and platinum substrates and lanthanum aluminate single crystal substrates by polymer assisted deposition. The dielectric properties of high quality polycrystalline and epitaxial CCTO films are tested. The results show that the dielectric constant of the prepared CCTO films is large and the dielectric loss is very large, which directly hinders the application of high dielectric material CCTO in electronic devices. In order to explore more accurately the nature of dielectric loss in CCTO, two effective methods are explored in this paper to reduce the loss: 1, and to prepare CCTO thin films by macromolecule assisted deposition under certain high pressure and high pure oxygen conditions. By controlling the pure oxygen at a certain pressure, the oxygen vacancy defects in the microstructure can be greatly reduced, and then the dielectric loss can be reduced. However, when the pressure exceeds the fixed threshold, the lattice mismatch between the film and the substrate exists and the thermal expansion does not match. Factors such as pressure and pressure will lead to a great change of cell volume, which will lead to a series of dislocations, defects, domain boundaries and lattice distortions. These changes will lead to new space charges, resulting in a sudden increase in dielectric loss at low frequency. The dielectric loss of CCTO prepared on single crystal substrate LaAlO3 (LAO) (001 is 0.002 ~ 0. 01 (10-100kHz) when the high pressure is 0.35 ~ 0. 75 MPA and the atmosphere is high purity oxygen (99. 999%). When the pressure is 0.55Mpa, the dielectric loss is the lowest, and the loss angle tangent value tan 未 鈮，
本文编号：2216078
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