鐵酸鉍異質(zhì)結(jié)阻變特性與機制研究
發(fā)布時間：2018-09-06 08:14
【摘要】：多鐵性鐵酸鉍(BiFeO3,簡稱BFO)材料是目前唯一在室溫同時具有鐵電和鐵磁性的多鐵性材料,具有優(yōu)異的鐵電和磁電耦合特性,在新型非揮發(fā)性存儲器件、多功能傳感器件、自旋電子器件、光伏器件等領(lǐng)域具有廣闊的應用前景。鐵酸鉍基阻變存儲器件結(jié)合了鐵電存儲器和阻變存儲器的優(yōu)點,通過鐵電極化的反轉(zhuǎn)調(diào)控界面勢壘和載流子輸運特性,以此來實現(xiàn)高低阻態(tài)切換,而非缺陷調(diào)控阻變行為,顯示出獨特的優(yōu)勢。本論文圍繞鐵酸鉍基阻變結(jié)構(gòu),構(gòu)筑了鐵酸鉍/金屬和鐵酸鉍/半導體兩種異質(zhì)結(jié)阻變結(jié)構(gòu),對鐵酸鉍薄膜和器件制備技術(shù)及阻變電學行為進行了研究,深入探討了異質(zhì)結(jié)構(gòu)的阻變機制、物理模型及主要調(diào)控因素。論文首先采用溶膠-凝膠法和脈沖激光沉積法在單晶硅和鈦酸鍶襯底上成功制備出具有良好鐵電性的高質(zhì)量鐵酸鉍薄膜,通過引入氧化物緩沖層、化學摻雜、以及控制氧壓與沉積溫度等減少薄膜缺陷與漏電路徑,獲得了致密、均勻、鐵電性能好、漏電流密度低的鐵酸鉍薄膜。同時,對鐵酸鉍進行雙金屬離子摻雜,獲得了具有一定鐵磁性的鐵酸鉍材料;并采用無磁性鎂元素摻雜制備鐵酸鉍納米結(jié)構(gòu)提升其磁性,獲得了鐵磁性與順磁性共存的鐵酸鉍納米結(jié)構(gòu)。設計并制備了Au/BFO/SRO異質(zhì)結(jié)阻變結(jié)構(gòu),在無需電成型操作下,獲得了具有自限流特性且可靠性高的雙極性阻變行為。設計并實現(xiàn)了對鐵酸鉍電阻狀態(tài)的有效調(diào)控,通過設置不同的掃描電壓、外加限流、掃描模式等方法獲得多個有效的存儲狀態(tài),證明其具有多值存儲能力。從電極材料、鐵電極化、材料缺陷等分析了鐵酸鉍材料的阻變機制,結(jié)合其電學行為及對溫度與測試氛圍依賴性的結(jié)果,證明鐵電極化調(diào)控界面勢壘及載流子輸運特性的阻變機制,并揭示了鐵電極化反轉(zhuǎn)與氧空位的遷移在鐵酸鉍阻變行為中的競爭機制,獲得了影響鐵酸鉍阻變特性的關(guān)鍵因素。此外,根據(jù)此阻變模型,對自限流特性及多值行為進行了解釋。設計并制備了BFO/ZnO異質(zhì)結(jié)阻變結(jié)構(gòu),獲得了雙穩(wěn)高低阻態(tài)切換特性及二極管整流效應。研究了薄膜厚度及鐵電材料的化學摻雜對異質(zhì)結(jié)阻變效應的影響,建立并完善了BFO/ZnO異質(zhì)結(jié)阻變物理模型,通過極化效應調(diào)控界面載流子耗盡或積累態(tài),并將鐵電極化引入異質(zhì)結(jié)能帶結(jié)構(gòu)中,推導出鐵酸鉍與氧化鋅的界面勢壘,獲得了鐵電極化調(diào)控異質(zhì)結(jié)阻變特性的方法及關(guān)鍵影響因素。
[Abstract]:Polyferric bismuth ferrate (BiFeO3,) is the only ferroelectric and ferromagnetic material at room temperature. It has excellent ferroelectric and magnetoelectric coupling properties. It is widely used in novel non-volatile memory devices and multifunctional sensing devices. Spin electronic devices, photovoltaic devices and other fields have a broad application prospects. Bismuth ferrite based resistive memory device combines the advantages of ferroelectric memory and resistive memory, and realizes the high and low resistance state switching, not the defect regulating the resistive behavior, through the inversion control interface barrier and carrier transport characteristics of iron electrode. Show unique advantages. In this thesis, two kinds of heterojunction structures, bismuth ferrate / metal and bismuth ferrate / semiconductor, are constructed around the structure of bismuth ferrate. The fabrication technology and the electrical resistance behavior of bismuth ferrate films and devices are studied. The resistance mechanism, physical model and main regulation factors of heterostructure are discussed. In this paper, high quality bismuth ferrite thin films with good ferroelectric properties were prepared on monocrystalline silicon and strontium titanate substrates by sol-gel method and pulsed laser deposition. By controlling the oxygen pressure and deposition temperature to reduce the defect and leakage path, dense, uniform, good ferroelectric properties and low leakage current density of bismuth ferrite thin films were obtained. At the same time, bismuth ferrate was doped by bimetallic ions to obtain bismuth ferrate material with certain ferromagnetism, and bismuth ferrate nanostructure was prepared by non-magnetic magnesium doping to enhance its magnetic properties. The ferromagnetic and paramagnetic bismuth ferrate nanostructures were obtained. The Au/BFO/SRO heterojunction resistive structure is designed and fabricated. The bipolar resistive behavior with self-limiting characteristics and high reliability is obtained without electroforming operation. The effective control of the state of bismuth ferrate resistance is designed and realized. By setting different scanning voltage, external current limiting, scanning mode and so on, several effective storage states are obtained, and it is proved that it has multi-value storage ability. The resistance mechanism of bismuth ferrate material was analyzed from the aspects of electrode material, iron electrode and material defect. The results of electrical behavior and dependence of temperature and test atmosphere on the resistance mechanism of bismuth ferrate material were analyzed. The resistance mechanism of interface barrier and carrier transport characteristics regulated by iron electrode is proved. The competitive mechanism of iron electrode inversion and oxygen vacancy migration in the resistance behavior of bismuth ferrate is revealed. The key factors affecting the resistance of bismuth ferrate are obtained. In addition, based on the resistive model, the self-limiting characteristics and multi-value behavior are explained. The BFO/ZnO heterojunction resistive structure is designed and fabricated. The bistable high and low resistive switching characteristics and diode rectifying effect are obtained. The effects of film thickness and chemical doping of ferroelectric materials on the heterojunction resistance were studied. The physical model of BFO/ZnO heterojunction resistance was established and improved. The interface carrier depletion or accumulation state was regulated by polarization effect. The interface barrier between bismuth ferrate and zinc oxide was deduced by introducing iron electrode into the heterojunction energy band structure. The method of controlling the resistance of heterojunction by iron electrode and the key influencing factors were obtained.
【學位授予單位】：清華大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ135.32;TP333
[Abstract]:Polyferric bismuth ferrate (BiFeO3,) is the only ferroelectric and ferromagnetic material at room temperature. It has excellent ferroelectric and magnetoelectric coupling properties. It is widely used in novel non-volatile memory devices and multifunctional sensing devices. Spin electronic devices, photovoltaic devices and other fields have a broad application prospects. Bismuth ferrite based resistive memory device combines the advantages of ferroelectric memory and resistive memory, and realizes the high and low resistance state switching, not the defect regulating the resistive behavior, through the inversion control interface barrier and carrier transport characteristics of iron electrode. Show unique advantages. In this thesis, two kinds of heterojunction structures, bismuth ferrate / metal and bismuth ferrate / semiconductor, are constructed around the structure of bismuth ferrate. The fabrication technology and the electrical resistance behavior of bismuth ferrate films and devices are studied. The resistance mechanism, physical model and main regulation factors of heterostructure are discussed. In this paper, high quality bismuth ferrite thin films with good ferroelectric properties were prepared on monocrystalline silicon and strontium titanate substrates by sol-gel method and pulsed laser deposition. By controlling the oxygen pressure and deposition temperature to reduce the defect and leakage path, dense, uniform, good ferroelectric properties and low leakage current density of bismuth ferrite thin films were obtained. At the same time, bismuth ferrate was doped by bimetallic ions to obtain bismuth ferrate material with certain ferromagnetism, and bismuth ferrate nanostructure was prepared by non-magnetic magnesium doping to enhance its magnetic properties. The ferromagnetic and paramagnetic bismuth ferrate nanostructures were obtained. The Au/BFO/SRO heterojunction resistive structure is designed and fabricated. The bipolar resistive behavior with self-limiting characteristics and high reliability is obtained without electroforming operation. The effective control of the state of bismuth ferrate resistance is designed and realized. By setting different scanning voltage, external current limiting, scanning mode and so on, several effective storage states are obtained, and it is proved that it has multi-value storage ability. The resistance mechanism of bismuth ferrate material was analyzed from the aspects of electrode material, iron electrode and material defect. The results of electrical behavior and dependence of temperature and test atmosphere on the resistance mechanism of bismuth ferrate material were analyzed. The resistance mechanism of interface barrier and carrier transport characteristics regulated by iron electrode is proved. The competitive mechanism of iron electrode inversion and oxygen vacancy migration in the resistance behavior of bismuth ferrate is revealed. The key factors affecting the resistance of bismuth ferrate are obtained. In addition, based on the resistive model, the self-limiting characteristics and multi-value behavior are explained. The BFO/ZnO heterojunction resistive structure is designed and fabricated. The bistable high and low resistive switching characteristics and diode rectifying effect are obtained. The effects of film thickness and chemical doping of ferroelectric materials on the heterojunction resistance were studied. The physical model of BFO/ZnO heterojunction resistance was established and improved. The interface carrier depletion or accumulation state was regulated by polarization effect. The interface barrier between bismuth ferrate and zinc oxide was deduced by introducing iron electrode into the heterojunction energy band structure. The method of controlling the resistance of heterojunction by iron electrode and the key influencing factors were obtained.
【學位授予單位】：清華大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ135.32;TP333
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