钙钛矿异质结构的制备和阻变存储性能研究

发布时间：2018-03-06 19:51

  本文选题：钙钛矿氧化物　切入点：脉冲激光沉积　出处：《南京大学》2015年硕士论文　论文类型：学位论文

【摘要】：钙钛矿氧化物具有十分丰富的物理和化学性质,例如铁磁性、铁电性、巨磁阻效应等,使其在存储及传感等方面都具有广阔的应用前景。因此,引起了广泛的关注。本文期望通过制备几种钙钛矿异质结,研究其电、磁特性,探索钙钛矿氧化物在存储方面的应用。本文采用脉冲激光沉积技术制备了CaMnO3/La0.7Sr0.3MnO3,TiO2/LaAlO3,以及SrRuO3/Pr0.8Ca0.2MnO3/SrTiO3(BaTiO3)/La0.7Sr0.3MnO3异质结构,优化了薄膜工艺,测量了晶体结构、点磁特性,采用微加工手段制备了相关原型器件并测试了存储功能。具体工作包括：(1)在LaA103衬底上沉积了CaMnO3/La0.7Sr0.3MnO3异质结构,原子力显微表面形貌测试表明表面较为平整,X射线衍射结果表明CaMnO3处于拉应力状态。压电力显微结果显示可以在CaMnO3表面用相反的电压形成约180°的相位衬度,振幅图上也可以观察到明显的畴壁,表明应变CaMnO3有可能具有铁电性。(2)Pt/TiO2/Pt阻变异质结构中,通过在Ti02层和Pt底电极之间加入LaAlO3层,提高了阻变性能。加入30 nm的LaAlO3层后,开关电压的不稳定性得到了有效的抑制,电阻开关比也从102提高到了103。X射线光电子能谱分析表明Ti02层中有大量的氧空位,在外加电场作用下,氧空位能够迁移到LaAlO3层中形成导电通道。TiO2/LaAlO3异质结高阻态的阻值随着LaAlO3层厚度的增加而增大,而低阻态的阻值则与LaAlO3层厚度无关,表明了导电细丝的形成与断裂优先发生在LaAlO3层中。(3)制备了SrRuO3/Pr0.8Ca0.2Mno3/SrTio3/La0.7Sr0.3MnO3全氧化物自旋过滤磁隧道结,在外加磁场下,隧道结呈现出高低两个阻态,隧穿磁电阻约为4%。用铁电BaTiO3代替SrTiO3隧穿层,在SrTiO3衬底上制备了SrTiO3多铁性隧道结,同时获得约1%的隧穿磁电阻和约100%的隧穿电致电阻。
[Abstract]:Perovskite oxides have abundant physical and chemical properties, such as ferromagnetism, ferroelectrics, giant magnetoresistive effect and so on. In this paper, we hope to study the electrical and magnetic properties of perovskite oxides and to explore the application of perovskite oxides in storage by preparing several perovskite heterostructures. In this paper, CaMnO _ 3 / La _ (0.7) Sr _ (0.3) mn O _ (3) O _ (2) / La _ (Alo) _ 3 and SrRuO3/Pr0.8Ca0.2MnO3/SrTiO3(BaTiO3)/La0.7Sr0.3MnO3 heterostructures have been prepared by pulsed laser deposition. The thin film process was optimized, the crystal structure and the point magnetic properties were measured, the related prototype devices were fabricated by microfabrication and the storage function was tested. The specific work includes: 1) depositing the CaMnO3/La0.7Sr0.3MnO3 heterostructure on the LaA103 substrate. The surface morphology of atomic force microscopy shows that the surface is flat and the X-ray diffraction results show that CaMnO3 is in the state of tensile stress, and the PPM results show that the phase contrast can be formed on the surface of CaMnO3 with the opposite voltage about 180 掳. The apparent domain walls can also be observed on the amplitude diagram, which indicates that the strain CaMnO3 may have ferroelectrics. T / TIO _ 2 / Pt resistive variant structure. By adding the LaAlO3 layer between the Ti02 layer and the Pt substrate electrode, the resistance property is improved. After the addition of 30 nm LaAlO3 layer, The instability of switching voltage is effectively suppressed, and the ratio of resistance to switch is increased from 102 to 103. X-ray photoelectron spectroscopy (XPS) analysis shows that there are a lot of oxygen vacancies in the Ti02 layer under the action of an external electric field. The oxygen vacancy can migrate to LaAlO3 layer to form conductive channel. TIO _ 2 / LaAlO _ 3 heterojunction high resistance state increases with the increase of LaAlO3 layer thickness, while the low resistance state resistance value is independent of LaAlO3 layer thickness. The results show that the formation and fracture of conductive filaments preferentially occur in the LaAlO3 layer. The SrRuO3/Pr0.8Ca0.2Mno3/SrTio3/La0.7Sr0.3MnO3 full oxide spin-filtered magnetic tunnel junctions are prepared. The tunneling junctions exhibit high and low resistive states under the external magnetic field. The tunneling magnetoresistance is about 4. Ferroelectric BaTiO3 instead of SrTiO3 tunneling layer is used to fabricate SrTiO3 multiferroelectric tunneling junction on SrTiO3 substrate. At the same time, about 1% tunneling magnetoresistance and about 100% tunneling resistance are obtained.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.32

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