兰州大学机构库 >物理科学与技术学院
稀释磁性半导体CoxTi1-xO2的制备与磁性研究
Alternative TitleStudy of Preparation and Magnetic Properties of Diluted Magnetic Semiconductor (DMS) CoxTi1-xO2
杨建洪
Thesis Advisor葛世慧
2004-05-12
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword稀释磁性半导体 DMS
Abstract磁性半导体同时具有磁性和半导体性质,是自旋电子学中的重要材料。磁性半导体作为铁磁体和半导体之间的理想界面,是实现新型半导体器件的理想材料。由于TiO2本身具有很好的物化特性,如高的折射率、在可见光和红外范围极好的透光性以及高的介电常数、光催化等独特的性质,因此由Co掺杂TiO2所形成的透明铁磁体CoxTi1-xO2有很好的应用前景。 本文采用脉冲激光沉积镀膜和溶胶-凝胶法分别制备了CoxTi1-xO2薄膜和粉末样品,探索了获得居里点在室温以上的透明铁磁性半导体的制备方法和工艺条件;并利用x射线衍射、振动样品磁强计、超导量子干涉磁强计、四端法测量电阻率等详细研究了薄膜样品和粉末样品的微结构、磁性以及电学性质。 对薄膜样品, 主要工作如下: (1) 采用脉冲激光沉积(PLD)技术,通过改变沉积频率和沉积过程中的氧气压,成功制备了CoxTi1-xO2薄膜样品。 (2) 测试结果表明,CoxTi1-xO2薄膜中Co:Ti的化学成份比例关系与预期实验数据相符,约为6%at。 (3) XRD实验结果表明,CoxTi1-xO2薄膜样品具有锐钛矿结构,并且存在织构现象。 (4) SQUID实验结果表明,CoxTi1-xO2薄膜样品在室温下仍然具有铁磁性。矫顽力、剩磁比、饱和磁化强度等磁学参数与样品生长时的氧气压和脉冲激光的频率有关。 对粉末样品: (1) 采用溶胶-凝胶方法成功制备了CoxTi1-xO2粉末样品,利用XRD和VSM对其进行了结构和磁性的基本研究;研究了烧结温度和时间对晶体结构和磁性的影响。 (2) 原子吸收光谱实验结果表明,CoxTi1-xO2粉末样品中的Co:Ti化学成份比例基本符合预期实验数据,约为3%at,在理论范围以内。 (3) XRD研究结果表明,CoxTi1-xO2粉末样品的晶体结构对烧结温度具有明显的依赖关系:在较低的温度下烧结,主要出现锐钛矿结构,而在较高的温度下主要得到金红石结构。而在相同的烧结温度下,烧结时间对晶粒尺寸和结构有很大的影响。烧结时间越长晶粒尺寸越大。 晶格畸变与不同温度下烧结的时间有关。 "
Other AbstractDiluted Magnetic Semiconductor (DMS), which own both of the magnetic and semiconductor characteristics, is an important spintronics materials. Today semiconductors in electric device and integrate circuit are nonmagnetic. As an ideal interface between the ferromagnet and the semiconductor, DMS is an ideal materials for fabricating the new type semiconductor devices. Due to the good physical and chemical properties of TiO2, such as high refractive index, permanent in visible and infrared light (CoxTi1-xO2 is called transparent ferromagnetic semiconductor), and high dielectric constant, these DMS are promising in application. In this paper,the CoxTi1-xO2 thin films and the powder samples were fabricated by pulse laser deposition(PLD) technique and the sol-gel method, respectively. The various experimental conditions were investigated in order to obtain the transparent ferromagnetic CoxTi1-xO2 samples with Curie point above room temperature. The crystal structure, chemical composition and magnetic and transport properties were studied with XRD, XPS, SQUID and macro-electrical measurements, respectively. For the thin film samples: 1) CoxTi1-xO2 thin films were fabricated by PLD technique. The main content are as fullows: through to changing the frequency of the pulse laser and the pressure of Oxygen during deposition 2) Theatomic ration of Co:Ti in the CoxTi1-xO2 is 6%At,which is the chemical components proportion Co:Ti in film is consistent with theexpected value 3) The result of XRD indicates that CoxTi1-xO2 film has the anatase structure with good texture. 4) The magnetic properties of CoxTi1-xO2 were investigated by SQUID. The Curie point is above the room temperature. The coercive force, saturated magnetization and the remanent magnetization is related to the experimental condition, such as the pressure of the oxygen and the frequency of the pulse laser during the deposition. For the powder samples: 1). CoxTi1-xO2 power samples were prepared by Sol-gel method the structure and magnetic properties of CoxTi1-xO2 were studied by XRD and VSM, respectively. The sintering temperature and time on crystal structure and magnetic properties of CoxTi1-xO2 were investigated. 2). The result of atomic absorption spectrum indicates that x=0.03, which in CoxTi1-xO2 is consistent with the expected magnitude of x. 3). The result of XRD indicates that the crystal structure of CoxTi1-xO2 is related to the sintering temperature. At low temperature, the anatase phase...
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Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229202
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
杨建洪. 稀释磁性半导体CoxTi1-xO2的制备与磁性研究[D]. 兰州. 兰州大学,2004.
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