本文選題：鐵電存儲(chǔ)器 + Bi_4Ti_3O_(12)鐵電材料�。� 參考：《武漢大學(xué)》2010年博士論文

【摘要】： 稀土離子摻雜的Bi4Ti3O12(BTO)基鐵電薄膜具有優(yōu)異的鐵電和抗疲勞特性,在新型非易失性鐵電存儲(chǔ)器等方面具有潛在的應(yīng)用前景。本論文采用溶膠-凝膠工藝制備了A位鑭系元素(La, Nd,Tb)、A位Nd和B位Mn共摻雜的BTO基鐵電薄膜,研究了摻雜離子對(duì)BTO薄膜結(jié)構(gòu)和電性能的影響；研究了不同晶種層對(duì)Bi3.25La0.75Ti3O12(BLT)薄膜的結(jié)晶取向和鐵電性能的影響；最后采用絕緣性能好的Bi3.15Nd0.85Ti3O12(BNT)鐵電薄膜作為緩沖層,與多鐵材料BiFeO3 (BFO)復(fù)合制成BNT/BFO多層薄膜,研究了BNT鐵電薄膜對(duì)BFO多鐵薄膜電性能的影響。主要內(nèi)容如下： 1.利用溶膠-凝膠法在Pt/TiO2/SiO2/Si襯底上制備了具有隨機(jī)取向的單相層狀鈣鈦礦結(jié)構(gòu)的BLT和BNT薄膜。掃描電鏡(SEM)的觀測(cè)顯示了這些薄膜具有50—100納米大小的晶粒構(gòu)成的均勻致密的的表面形貌。這些薄膜電容顯示了很好的飽和電滯回線(xiàn)。在最大外加場(chǎng)強(qiáng)為400kV/cm時(shí),得到BLT薄膜的剩余極化強(qiáng)度(2Pr)和矯頑電場(chǎng)(2Ec)分別為25.1μC／cm2和203kV／cm,BNT薄膜的分別為44.2μC／cm2和296kV／cm。而且,在1MHz頻率測(cè)試下經(jīng)過(guò)1.75×1010次讀寫(xiě)循環(huán)后,由BLT和BNT薄膜組成的電容器幾乎沒(méi)有表現(xiàn)出疲勞,呈現(xiàn)很好的抗疲勞特性。分析比較了La和Nd摻雜對(duì)薄膜結(jié)構(gòu)及鐵電性能的影響及其機(jī)理。 2.首次采用Sol-gel技術(shù)在Pt/TiO2/SiO2/Si襯底上制備了高價(jià)Tb4+摻雜BTO的Bi4-xTbxTi3O12(BTTx)薄膜。BTTx薄膜表現(xiàn)出多晶鈣鈦礦結(jié)構(gòu),具有飽和的電滯回線(xiàn)。相比于純BTO薄膜,BTT薄膜具有以下改善的性能：(i)在外加最大電場(chǎng)為540kV/cm時(shí),具有飽和的電滯回線(xiàn)、大的剩余極化值(Pr～60μC／cm2)及小的矯頑電場(chǎng)(Ec～298 kV／cm)；(ii)在經(jīng)過(guò)1.0×1010極化反轉(zhuǎn)后,BTT薄膜表現(xiàn)出無(wú)疲勞特征。這表明高價(jià)Tb4+的摻雜明顯提高了BTO薄膜的鐵電性能和抗疲勞特性,這可能歸因于Tb4+的摻雜引起的薄膜的晶格畸變和可能降低的氧空位濃度。 3.采用Sol-gel法在Pt/TiO2/SiO2/Si襯底上制備了A位Nd和B位Mn摻雜的Bi3.15Nd0.85Ti3-xMnxO12 (BNTMX,x=0,0.01,0.03,0.05和0.1)薄膜。BNTM薄膜具有單相鈣鈦礦的多晶微結(jié)構(gòu)和均勻致密的的表面形貌。Mn的摻雜使BNTM薄膜的晶格產(chǎn)生明顯畸變。隨著Mn摻雜濃度的增加,BNTM薄膜的2Ec值逐漸降低,而2Pr值在x=0.05時(shí)具有最大值；Mn摻雜量為x=0.05的樣品具有最佳的電性能,在最大測(cè)試場(chǎng)強(qiáng)為400kV/cm時(shí),其2Pr和2Ec分別為38.3μC／cm2和180kV/cm。在f=1MHz時(shí),其介電常數(shù)和介電損耗分別為290和0.08。疲勞測(cè)試表明,經(jīng)過(guò)1.0×1010次讀寫(xiě)循環(huán)后,該薄膜電容器呈現(xiàn)優(yōu)良的抗疲勞特性。 4.采用Sol-gel技術(shù)在Pt／TiO2／SiO2／Si(100)襯底上分別制備了以Bi2O3、TiO2和BTO為晶種層的BLT鐵電薄膜。XRD結(jié)果表明不同的晶種層對(duì)BLT薄膜的取向具有不同的影響。含不同晶種層的BLT薄膜的表面形貌也不同,其結(jié)果同XRD分析結(jié)果相對(duì)應(yīng)。不同的晶種層對(duì)BLT薄膜的漏電流產(chǎn)生不同的影響,以TiO2晶種層制備的BLT薄膜的漏電流密度最小。鐵電性能分析表明在BTO晶種層上沉積BLT薄膜的剩余極化2Pr最大,為62.6μC／cm2,疲勞測(cè)試表明各薄膜均具有良好的抗疲勞特性,其中以TiO2為晶種層制備的BLT薄膜的抗疲勞特性最優(yōu)。 5.采用Sol-gel法在Pt／TiO2／SiO2／Si(100)襯底上制備了BFO/BNT多層薄膜。研究了室溫下復(fù)合薄膜的結(jié)構(gòu)、漏電流、鐵電和抗疲勞特性。相對(duì)于純的BFO薄膜,BFO/BNT多層薄膜具有更低的漏電流,能承受更高的測(cè)試電場(chǎng)而獲得充分極化,從而表現(xiàn)出優(yōu)良的鐵電性,在350kV/cm的測(cè)試電場(chǎng)強(qiáng)度下,剩余極化強(qiáng)度為55μC／cm2。在6V的測(cè)試電壓下,BFO/BNT薄膜的漏電流密度比純BFO薄膜的漏電流密度要低兩個(gè)數(shù)量級(jí)。
[Abstract]:Bi4Ti3O12 (BTO) based ferroelectric thin films doped with rare earth ions have excellent ferroelectric and fatigue properties, and have potential applications in the new nonvolatile ferroelectric memory. In this paper, the A bit lanthanide elements (La, Nd, Tb), A bit Nd and B Mn Co doped BTO based ferroelectric thin films were prepared by the sol-gel process. The influence of the sub layer on the structure and electrical properties of BTO film was studied. The influence of different seed layers on the crystalline orientation and ferroelectric properties of Bi3.25La0.75Ti3O12 (BLT) thin films was studied. Finally, the Bi3.15Nd0.85Ti3O12 (BNT) ferroelectric thin film was used as the buffer layer and the BiFeO3 (BFO) of the polyiron material was combined to make the BNT/BFO multilayer film, and the BNT iron was studied. The effect of electric thin film on the electrical properties of BFO multiferroic thin films is as follows:
1. BLT and BNT films with random orientation of single-phase layered perovskite structure were prepared on Pt/TiO2/SiO2/Si substrate by sol-gel method. The observation of scanning electron microscopy (SEM) shows that these films have uniform and dense surface morphology composed of 50 to 100 nanocrystalline grains. These films show good saturated hysteresis. When the maximum applied field intensity is 400kV/cm, the residual polarization (2Pr) and coercive electric field (2Ec) of the BLT film are 25.1 mu C / cm2 and 203kV / cm respectively. The BNT thin films are respectively 44.2 mu C / cm2 and 296kV / cm. After 1.75 * 1010 cycles of reading and writing under the frequency test, the capacitor is almost no more. Fatigue and good fatigue resistance were observed. The effects of La and Nd doping on the structure and ferroelectric properties of the films were analyzed and compared.
2. the Bi4-xTbxTi3O12 (BTTx) thin film.BTTx film of high valence Tb4+ doped BTO was prepared on Pt/TiO2/SiO2/Si substrate by Sol-gel technology for the first time, showing a polycrystalline perovskite structure with a saturated hysteresis loop. Compared with the pure BTO film, the BTT thin film has the following improved properties: (I) with the maximum applied electric field as 540kV/cm, it has saturated electricity. The hysteresis loop, large residual polarization (Pr ~ 60 / C / cm2) and small coercive electric field (Ec to 298 kV / cm). (II), after 1 x 1010 polarization reversal, BTT film has no fatigue characteristics. This indicates that the doping of high price Tb4+ obviously improves the ferroelectric and fatigue resistance of BTO films, which may be attributed to the film caused by Tb4+ doping. Lattice distortion and possible reduced oxygen vacancy concentration.
3. A Nd and B bit Mn doped Bi3.15Nd0.85Ti3-xMnxO12 (BNTMX, x=0,0.01,0.03,0.05 and 0.1) thin film.BNTM films were prepared on Pt/TiO2/SiO2/Si substrates by Sol-gel method. The polycrystalline microstructures of single-phase perovskite and homogeneous and dense surface morphology were doped to make the lattice of the BNTM thin film produced obvious distortion. The 2Ec value of the BNTM film decreases gradually and the 2Pr value has the maximum value at x=0.05; the sample with Mn doping amount of x=0.05 has the best electrical properties. When the maximum test field strength is 400kV/cm, its 2Pr and 2Ec are 38.3 mu C / cm2 and the dielectric loss is 290 and the fatigue test shows that the dielectric constant and the dielectric loss are respectively indicated by the fatigue test. After 1 x 1010 cycles, the film capacitors exhibit excellent fatigue resistance.
4. Sol-gel technique was used to prepare BLT ferroelectric thin film.XRD with Bi2O3, TiO2 and BTO as the crystal layer on Pt / TiO2 / SiO2 / Si (100) substrate. The results show that different crystal layers have different influences on the orientation of BLT film. The surface morphology of the BLT films with different seed layers is different, and the results are different from those of the analytical results. The crystal layer has a different effect on the leakage current of the BLT film. The leakage current density of the BLT film prepared in the TiO2 seed layer is the smallest. The ferroelectric performance analysis shows that the maximum residual polarization 2Pr of the BLT film deposited on the BTO seed layer is 62.6 mu C / cm2. The fatigue test shows that the thin films have good anti fatigue properties, and TiO2 is the crystal seed. The anti fatigue properties of the BLT films prepared by the layer are the best.
5. the BFO/BNT multilayer films were prepared on Pt / TiO2 / SiO2 / Si (100) substrates by Sol-gel method. The structure, leakage current, ferroelectric and anti fatigue properties of the composite films at room temperature were studied. Relative to pure BFO films, BFO/BNT multilayer films have lower leakage current and can withstand a higher test electric field. Under the test electric field of 350kV/cm, the residual polarization intensity is 55 mu C / cm2. at the test voltage of 6V, and the leakage current density of BFO/BNT thin film is two orders of magnitude lower than that of pure BFO film.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2010
【分類(lèi)號(hào)】：O484.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前5條

1 申林,肖定全,余萍,朱建國(guó),朱居木,高道江;溶膠-凝膠技術(shù)制備(Bi_(4-x),La_x)Ti_3O_(12)陶瓷的工藝技術(shù)研究[J];功能材料;2002年04期

2 ;Microstructures and fatigue-free properties of the La~(3+) and Nd~(3+) doped Bi_4Ti_3O_(12) thin films prepared by modified sol-gel technique[J];Science in China(Series E:Technological Sciences);2008年11期

3 朱駿,毛翔宇,陳小兵;Bi_(4-x)La_xTi_3O_(12)-SrBi_(4-y)La_yTi_4O_(15)共生結(jié)構(gòu)鐵電材料拉曼光譜研究[J];物理學(xué)報(bào);2004年11期

4 何恩培，，劉梅冬，盧春如;溶膠一凝膠工藝對(duì)PZT鐵電薄膜結(jié)構(gòu)的影響[J];壓電與聲光;1994年05期

5 陳敏;黃可龍;梅孝安;黃重慶;劉靖;蔡安輝;;Electrical characteristics and microstructures of Pr_6O_(11)-doped Bi_4Ti_3O_(12) thin films[J];Transactions of Nonferrous Metals Society of China;2009年01期

本文編號(hào)：1901946