【摘要】：本文通過高分子輔助沉積法,在銅、金和鉑等金屬基底以及鋁酸鑭單晶基底上嘗試制備CaCu3Ti4O12(CCTO)薄膜,通過對制備工藝的不斷調(diào)整與優(yōu)化,分別制備出了成膜均勻、質(zhì)量較高的多晶和外延CCTO薄膜,對薄膜進(jìn)行介電性能測試,結(jié)果表明制得的CCTO薄膜的介電常數(shù)較大,而介電損耗也非常大,直接阻礙了高介電材料CCTO在電子器件中的應(yīng)用,為更準(zhǔn)確探究CCTO內(nèi)部介電損耗的本質(zhì),本文主要探尋兩種有效的方法可以降低損耗:1,在一定的高壓范圍,高純氧條件下,通過高分子輔助沉積法制備CCTO薄膜。通過控制一定壓強(qiáng)的純氧,可大幅減少微觀結(jié)構(gòu)內(nèi)的氧空位缺陷,繼而降低其介電損耗,但壓強(qiáng)大過固定閾值時,薄膜與基片間存在的晶格失配、熱膨脹不匹配,以及氣壓壓強(qiáng)等因素,將導(dǎo)致晶胞體積發(fā)生較大改變,繼而引發(fā)一系列的位錯、缺陷、疇界和晶格畸變,這些變化又會引發(fā)新的空間電荷,使低頻段的介電損耗驟增。當(dāng)高壓處于0.35~0.75Mpa,氣氛為高純氧(99.999%)時,在單晶基底LaAlO3(LAO)(001)上制備得到的CCTO的介電損耗為0.002~0.01(10-100kHz),當(dāng)氣壓為0.55Mpa時,介電損耗最低,損耗角正切值tanδ≈0.002(10-100kHz)。2,通過對CCTO薄膜進(jìn)行鋯摻雜,高壓下?lián)诫s燒結(jié),薄膜的介電損耗先增大后減小。常壓下?lián)诫s燒結(jié),CCTO的介電損耗先減小后增大。不同氣壓和不同摻雜量,Zr離子堆積的主要位置也不相同,一部分進(jìn)入晶界,阻礙自由電子移動,減小漏電流,增大了晶界的絕緣性,降低損耗,另一部分進(jìn)入晶粒,取代Ti離子,導(dǎo)致TiO6八面體結(jié)構(gòu)更加失衡、不對稱,介電損耗大幅增大,氣壓條件與摻雜改性共同決定了,Zr離子的主要堆積位置,繼而對CCTO薄膜介電損耗產(chǎn)生不同影響,結(jié)果表明,常壓下5%-10%的摻雜量下,CCTO薄膜的介電損耗得到了最大改善,損耗角正切值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，

本文編號：2216078