本文選題：交替摻雜 + 鈦酸鍶鋇薄膜��； 參考：《電子科技大學(xué)》2015年碩士論文

【摘要】：BST鐵電薄膜因其具有良好的鐵電、介電、壓電等方面的特性,成為近年來研究的一個(gè)熱點(diǎn)。其優(yōu)良的性能可以使其應(yīng)用在移相器、動(dòng)態(tài)隨機(jī)存儲(chǔ)器等微波調(diào)諧器件當(dāng)中。然而,應(yīng)用在微波調(diào)諧領(lǐng)域要求BST薄膜必須同時(shí)具有高的調(diào)諧率和低的介電損耗。純的BST雖然可以達(dá)到較高的調(diào)諧率,但是介電損耗較高阻礙了其應(yīng)用。為了克服這一缺點(diǎn),本研究團(tuán)隊(duì)前期進(jìn)行了大量的研究,包括改進(jìn)薄膜的制備工藝、進(jìn)行單一摻雜、復(fù)合摻雜以及交替摻雜來提高薄膜的綜合介電性能,都取得了良好的進(jìn)展。尤其是釔(Y)和錳(Mn)交替摻雜對于提高薄膜的綜合介電性能有著良好的促進(jìn)作用。本團(tuán)隊(duì)在研究中發(fā)現(xiàn),在制備薄膜的過程中加入預(yù)熱處理過程可以大大的改善薄膜的性能,目前關(guān)于這方面的研究還比較欠缺。因此,本論文在前期研究的基礎(chǔ)上,重點(diǎn)研究不同的預(yù)熱處理方式以及不同的摻雜濃度組合對釔(Y)和錳(Mn)交替摻雜薄膜的介電性能的影響,并深入地分析了其機(jī)理。利用XRD、SEM以及HP4294A阻抗分析儀測試了薄膜的相結(jié)構(gòu)、表面形貌及介電性能,取得了以下創(chuàng)新性成果:1、適當(dāng)?shù)念A(yù)熱處理可以有效地提高薄膜的綜合介電性能,不僅使薄膜保持較高的調(diào)諧率,且可以有效地降低介電損耗。其中,在600℃條件下進(jìn)行預(yù)熱處理,保持Y的摻雜濃度為1%不變,隨著Mn的摻雜濃度從2%升到5%,薄膜的介電損耗經(jīng)歷了先減小后增大的過程,當(dāng)Mn的摻雜濃度為3%時(shí),薄膜的調(diào)諧率為47.90%,最大介電損耗低至1.98%;在650℃條件下進(jìn)行預(yù)熱處理,薄膜性能有所提高,3mol%Mn/1mol%Y薄膜的最大介電損耗降低至1.38%,調(diào)諧率為48.2%。2、對薄膜的預(yù)熱處理溫度進(jìn)行進(jìn)一步優(yōu)化,在550℃條件下進(jìn)行預(yù)熱處理,獲得了較其他單一溫度預(yù)熱處理更低的介電損耗,隨著Mn的濃度從2%升到5%,薄膜的最低介電損耗分別為0.79%、0.97%、0.92%,均在1%以下。并且在降低了損耗的基礎(chǔ)上,保持了較高的調(diào)諧率,三種濃度下薄膜的調(diào)諧率依次為56%、56%、48.6%,表現(xiàn)出優(yōu)異的介電性能。3、在單一溫度預(yù)熱處理方式的基礎(chǔ)上,提出了一種新型的預(yù)熱處理方式:梯度預(yù)熱處理。隨著薄膜層數(shù)的增加,薄膜的預(yù)熱處理溫度呈現(xiàn)梯度的變化,由第一層的550℃逐漸升高到了第六層的650℃。在此預(yù)熱處理方式下,隨著Mn摻雜濃度的增大,薄膜的晶化逐漸增強(qiáng),晶粒尺寸逐漸增大。薄膜的綜合介電性也能得到了大幅度的提升,保持Y的摻雜濃度不變,當(dāng)Mn的摻雜濃度為2%時(shí),薄膜的最大損耗和最低損耗分別為1.4%和0.49%,同時(shí)對應(yīng)高達(dá)50.2%的調(diào)諧率;當(dāng)Mn的摻雜濃度為3%時(shí),薄膜的最高損耗和最低損耗分別為1.3%和0.404%;隨著Mn的濃度的進(jìn)一步的升高,介電損耗有所升高,但是仍然保持在較低的水平,當(dāng)Mn的濃度為6%時(shí),最高損耗和最低損耗分別為1.33%和0.635%。SEM測試結(jié)果也表明:經(jīng)過梯度預(yù)熱處理的薄膜表面形貌良好,晶粒細(xì)小均勻,孔隙更少。
[Abstract]:BST ferroelectric thin films have become a hot research area in recent years because of their good ferroelectric, dielectric and piezoelectric properties. It can be used in microwave tuners such as phase shifters, dynamic random access memory (DRAM) and so on. However, in the field of microwave tuning, BST films must have high tuning rate and low dielectric loss. Although pure BST can achieve high tuning rate, high dielectric loss hinders its application. In order to overcome this shortcoming, the research team has done a lot of research, including improving the preparation process of thin films, single doping, composite doping and alternating doping to improve the comprehensive dielectric properties of the films, and has made good progress. In particular, the alternating doping of yttrium and manganin) has a good effect on improving the comprehensive dielectric properties of the films. The team found that the performance of the films can be greatly improved by adding preheating process in the process of preparing the films, but the current research on this aspect is still relatively lacking. Therefore, on the basis of previous studies, this paper focuses on the effects of different preheating methods and different doping concentration combinations on the dielectric properties of YY) and MnMnMn) alternate doped films, and the mechanism of them is analyzed in depth. The phase structure, surface morphology and dielectric properties of the films were measured by XRD-SEM and HP4294A impedance analyzer. The following innovative results were obtained: 1. Proper preheating treatment can effectively improve the comprehensive dielectric properties of the films. The film can not only keep a high tuning rate, but also reduce the dielectric loss effectively. The dielectric loss of the films decreases first and then increases with the increase of mn doping concentration from 2% to 5%. When mn doping concentration is 3%, the dielectric loss of the films decreases and then increases. The tunable rate of the film is 47.90, and the maximum dielectric loss is as low as 1.98. When the film is pretreated at 650 鈩，

本文編號：1932201