本文選題：交替摻雜 + 鈦酸鍶鋇薄膜　； 參考：《電子科技大學》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熱點。其優(yōu)良的性能可以使其應用在移相器、動態(tài)隨機存儲器等微波調諧器件當中。然而,應用在微波調諧領域要求BST薄膜必須同時具有高的調諧率和低的介電損耗。純的BST雖然可以達到較高的調諧率,但是介電損耗較高阻礙了其應用。為了克服這一缺點,本研究團隊前期進行了大量的研究,包括改進薄膜的制備工藝、進行單一摻雜、復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作用。本團隊在研究中發(fā)現,在制備薄膜的過程中加入預熱處理過程可以大大的改善薄膜的性能,目前關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上,重點研究不同的預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理。利用XRD、SEM以及HP4294A阻抗分析儀測試了薄膜的相結構、表面形貌及介電性能,取得了以下創(chuàng)新性成果:1、適當的預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諧率,且可以有效地降低介電損耗。其中,在600℃條件下進行預熱處理,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%,薄膜的介電損耗經歷了先減小后增大的過程,當Mn的摻雜濃度為3%時,薄膜的調諧率為47.90%,最大介電損耗低至1.98%;在650℃條件下進行預熱處理,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%,調諧率為48.2%。2、對薄膜的預熱處理溫度進行進一步優(yōu)化,在550℃條件下進行預熱處理,獲得了較其他單一溫度預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上,保持了較高的調諧率,三種濃度下薄膜的調諧率依次為56%、56%、48.6%,表現出優(yōu)異的介電性能。3、在單一溫度預熱處理方式的基礎上,提出了一種新型的預熱處理方式:梯度預熱處理。隨著薄膜層數的增加,薄膜的預熱處理溫度呈現梯度的變化,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,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Mn的摻雜濃度為2%時,薄膜的最大損耗和最低損耗分別為1.4%和0.49%,同時對應高達50.2%的調諧率;當Mn的摻雜濃度為3%時,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Mn的濃度為6%時,最高損耗和最低損耗分別為1.33%和0.635%。SEM測試結果也表明:經過梯度預熱處理的薄膜表面形貌良好,晶粒細小均勻,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