本文選題：水熱外延 + 非易失雙極阻變特性�。� 參考：《蘭州大學(xué)》2017年博士論文

【摘要】：阻變隨機存儲器(Resistance Random Access Memory,RRAM)是通過器件的電阻態(tài)可逆變化進行數(shù)據(jù)存儲的一類存儲器。它以簡單器件構(gòu)成(金屬-阻變層-金屬)、無損的數(shù)據(jù)讀寫方式、非易失性的存儲特性、高的存儲密度和操作速度、低功耗等優(yōu)勢被作為最有價值的新型非易失存儲器。RRAM的非易失性阻變特性與器件中的阻變層有著緊密聯(lián)系。現(xiàn)如今已經(jīng)在很多的材料中發(fā)現(xiàn)了非易失的阻變特性。其中,鈣鈦礦結(jié)構(gòu)氧化物作為一類具有獨特物理化學(xué)性質(zhì)的功能材料,有助于實現(xiàn)RRAM功能多元化、器件集成化,故而成為RRAM中被廣泛研究的一類材料。雖然至今為止,關(guān)于鈣鈦礦結(jié)構(gòu)氧化物的阻變存儲報道數(shù)量不少,但對于其中的阻變物理機制卻眾說紛紜。由于缺乏普適的物理機制,不利于鈣鈦礦結(jié)構(gòu)氧化物材料在RRAM中的設(shè)計、控制和應(yīng)用。本論文從同種結(jié)構(gòu)材料應(yīng)有普適物理機制的觀點出發(fā),基于鈣鈦礦結(jié)構(gòu)的材料,采用了異于傳統(tǒng)RRAM制備工藝的制備方法——水熱外延,以無機→無機-有機體系為研究思路,以鐵電(CaTiO_3)薄膜、多鐵(Bi Fe O_3)薄膜、(CH_3NH_3)_2Fe Cl_4(MAFC)為具體研究對象,系統(tǒng)地探究了鈣鈦礦結(jié)構(gòu)水熱外延薄膜的阻變特性根源及其阻變物理機制。獲得的結(jié)果概括如下:1.在利用水熱外延方法首次獲得CaTiO_3薄膜的基礎(chǔ)上,通過對Pt/CaTiO_3/Nb:Sr Ti O_3元件的I-V測試,觀察到了穩(wěn)定的非易失雙極阻變特性。該雙極阻變電導(dǎo)行為滿足空間電荷限制電流SCLC(Space Charge Limited Current)的傳導(dǎo)機制。充當(dāng)SCLC機制中“捕獲中心(Trap Centers)”的是CaTiO_3薄膜中大量的氧空位。在直流偏壓的作用下,薄膜中氧空位對自電極而來的注入電子實施了捕獲及釋放的操作,完成了Trapping及Detrapping過程。2.為驗證SCLC機制在其它鈣鈦礦結(jié)構(gòu)氧化物水熱外延薄膜中的普適性,我們又制備了高質(zhì)量的Bi Fe O_3薄膜,并首次在Pt/Bi Fe O_3/Nb:Sr Ti O_3中觀測到了三態(tài)的雙極阻變特性,同時,證實器件中的阻變行為依然與薄膜中大量的空位氧有直接關(guān)系,滿足SCLC的傳導(dǎo)機制。此外,Pt/Bi Fe O_3界面處Shottky勢壘高度和寬度隨掃描偏壓的變化亦對其阻變有貢獻。該工作為Pt/Bi Fe O_3/Nb:Sr Ti O_3阻變元件實現(xiàn)多值存儲奠定了實驗基礎(chǔ)。3.基于上述兩個工作,在獲得了高結(jié)晶度類鈣鈦礦結(jié)構(gòu)的MAFC晶體基礎(chǔ)上,首次在Ag/MAFC/Cu元件中觀測到了非易失的雙極阻變特性。該特性與器件在掃描偏壓作用下Ag/MAFC或Cu/MAFC界面處氧化層的形成與消散有關(guān)。4.在上一工作的研究過程中,我們發(fā)現(xiàn)MAFC晶體中的磁狀態(tài)對外磁場有著很強的依賴性,并隨外加磁場的不同表現(xiàn)出兩種磁狀態(tài)——弱的鐵磁有序和反鐵磁有序。這與該晶體在外磁場中磁性原子間長程超交換作用產(chǎn)生的反鐵磁傾斜有關(guān)。與此同時,發(fā)現(xiàn)MAFC在外加電場的作用下會發(fā)生鐵電極化。MAFC中磁電共存的發(fā)現(xiàn)為單相多鐵的研究提供了一種新途徑。
[Abstract]:Resistive random access memory (RRAM) is a kind of memory which can store data through the reversible change of the resistance state of the device. It is composed of simple devices (metal-resistive layer-metal, lossless data reading and writing, non-volatile storage characteristics, high storage density and operating speed, " Low power consumption and other advantages are regarded as the most valuable new non-volatile memory. RRAM has a close relationship with the resistive layer in the device. Non-volatile resistances have now been found in many materials. Perovskite oxide, as a kind of functional materials with unique physical and chemical properties, is helpful to realize the diversification of RRAM functions and the integration of devices. Therefore, perovskite oxide has been widely studied in RRAM. Although there are many reports about perovskite structure oxide resistance storage up to now, there are different opinions about the physical mechanism of perovskite structure oxide. Due to the lack of universal physical mechanism, it is unfavorable to the design, control and application of perovskite structure oxide materials in RRAM. From the point of view of the universal physical mechanism of the same structural material, based on the perovskite structure material, the hydrothermal epitaxy method, which is different from the traditional preparation process of RRAM, is adopted in this paper, and the inorganic organic system is taken as the research idea. Taking CaTiO3) thin films and BiFeO3) thin films as specific research objects, the source of resistance properties and the physical mechanism of perovskite structure hydrothermal epitaxial thin films are systematically investigated. The results are summarized as follows: 1. On the basis of the first CaTiO_3 thin films obtained by hydrothermal epitaxy, the stable non-volatile bipolar resistances have been observed by the I-V measurement of Pt/CaTiO_3/Nb:Sr TiO3 elements. The bipolar resistive conductance can satisfy the conduction mechanism of space charge-limited current (SCLC(Space Charge Limited Current). The "trap centers" in the SCLC mechanism are large oxygen vacancies in the CaTiO_3 films. Under the action of DC bias, the oxygen vacancy in the film traps and releases the injected electrons from the electrode, and completes the process of Trapping and Detrapping. In order to verify the universality of SCLC mechanism in other perovskite-structure oxide hydrothermal epitaxial films, we have prepared high quality BiFeO _ 3 thin films, and observed tri-state bipolar resistance in Pt/Bi Fe O_3/Nb:Sr TIO _ 3 for the first time. It is confirmed that the resistive behavior of the device is still directly related to the large amount of vacancy oxygen in the thin film, which satisfies the conduction mechanism of SCLC. In addition, the variation of the height and width of Shottky barrier at the interface of Pt / Bi Fe O 3 with the scan bias also contributes to its resistance. This work has laid the experimental foundation for the realization of multi-value storage of Pt/Bi Fe O_3/Nb:Sr TIO _ 3 resistor element. Based on the above two works, the nonvolatile bipolar resistance of MAFC crystals with high crystallinity perovskite-like structure has been observed for the first time in Ag/MAFC/Cu elements. This property is related to the formation and dissipation of oxide layer at the interface of Ag/MAFC or Cu/MAFC under the action of scanning bias. In the previous study, we found that the external magnetic field of the magnetic state in MAFC crystal is highly dependent and shows two magnetic states: weak ferromagnetic order and antiferromagnetic order with the difference of the external magnetic field. This is related to the antiferromagnetic tilt caused by the long range superexchange between magnetic atoms in the external magnetic field of the crystal. At the same time, the discovery of ferroelectric-magnetoelectric coexistence in MAFC under the action of an applied electric field provides a new way for the study of single-phase multi-iron.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TP333

【參考文獻】

相關(guān)期刊論文 前8條

1 張飛;林遠彬;吳昊;苗青;鞏紀軍;陳繼培;吳素娟;曾敏;高興森;劉俊明;;Asymmetric reversible diode-like resistive switching behaviors in ferroelectric BaTiO_3 thin films[J];Chinese Physics B;2014年02期

2 倪小靜;楊超云;;超導(dǎo)量子干涉器(SQUID)原理及應(yīng)用[J];物理與工程;2007年06期

3 劉歲林;田云飛;陳紅;吉曉江;;原子力顯微鏡原理與應(yīng)用技術(shù)[J];現(xiàn)代儀器;2006年06期

4 闞林生;;約瑟夫森效應(yīng)及其應(yīng)用的探討[J];安徽建筑工業(yè)學(xué)院學(xué)報(自然科學(xué)版);2006年02期

5 陳林;李敬東;唐躍進;任麗;;超導(dǎo)量子干涉儀發(fā)展和應(yīng)用現(xiàn)狀[J];低溫物理學(xué)報;2005年S1期

6 陳傳忠,包全合,姚書山,雷廷權(quán);脈沖激光沉積技術(shù)及其應(yīng)用[J];激光技術(shù);2003年05期

7 張英鴿;用原子力顯微技術(shù)測定生物分子之間的相互作用力[J];生物醫(yī)學(xué)工程學(xué)雜志;1998年04期

8 施爾畏，夏長泰，王步國，仲維卓;水熱法的應(yīng)用與發(fā)展[J];無機材料學(xué)報;1996年02期

相關(guān)博士學(xué)位論文 前4條

1 楊金;非揮發(fā)性阻變存儲器阻變機理及性能研究[D];安徽大學(xué);2014年

2 陳超;新型阻變存儲器材料及其電阻轉(zhuǎn)變機理研究[D];清華大學(xué);2013年

3 謝宏偉;二元過渡金屬氧化物的阻變存儲器研究[D];蘭州大學(xué);2013年

4 楊貴進;稀磁氧化物的制備及其鐵磁性研究[D];蘭州大學(xué);2012年

，

本文編號：1919512