【作者】 刘全生；

【导师】 张希艳；

【作者基本信息】 长春理工大学 ， 材料物理与化学， 2009， 博士

【摘要】 Mg_xZn_1-xO三元化合物是一种Ⅱ-Ⅵ族ZnO基半导体材料,室温下ZnO的禁带宽度约为3.3eV,MgO的禁带宽度约为7.8eV,Mg_xZn_1-xO薄膜的禁带宽度理论上可以从3.3eV到7.8eV连续可调,Mg_xZn_1-xO三元化合物禁带宽度的可调性,使Mg_xZn_1-xO三元化合物在紫外、可见光发射器件、日盲区紫外探测器等方面具有广阔的应用前景,成为当前的研究热点。本论文分别采用溶胶-凝胶旋涂法和射频磁控溅射法在蓝宝石、Si、石英玻璃和陶瓷等衬底上制备了不同组分的Mg_xZn_1-xO薄膜,通过光电子能量分散谱仪（EDS）、X射线衍射仪（XRD）和扫描电镜（SEM）表征了薄膜的组分、结构和表面形貌。通过紫外可见分光光度仪和紫外可见荧光光谱仪研究了薄膜的吸收、透射和发光性能。讨论了制备工艺对薄膜结构和光学性能的影响。采用光刻与湿化学刻蚀法在Si（111）/Mg_xZn_1-xO上制备了MSM结构的日盲区紫外探测器,采用霍尔测试仪和光谱响应测试系统研究了探测器的Ⅰ-Ⅴ特性和光谱响应特性。采用溶胶凝胶法制备了Mg_xZn_1-xO纳米粉体,并利用该粉体制备了Mg_xZn_1-xO陶瓷,采用XRD、分光光度仪和荧光光谱仪表征了纳米粉体和陶瓷的结构、发光性能和吸收、透过特性。取得以下主要研究成果:1.溶胶-凝胶旋涂法制备薄膜研究表明,在偏酸性条件下（pH值在6.5.7.0之间）,溶液温度为80℃,升温速率为2-4℃/min,稳定剂0.3ml/g的条件下获得质量较好的溶胶。在120℃下干燥,在300℃下热处理30min,在600℃下灼烧1h获得较佳薄膜样品。2.溶胶-凝胶旋涂法制备的薄膜组分与设计的组成一致。薄膜的结构随x值变化,当x≤0.33时,Mg_xZn_1-xO薄膜为六方ZnO结构,当x≥0.5时,Mg_xZn_1-xO薄膜为立方MgO结构,当0.33<x<0.5时,Mg_xZn_1-xO薄膜晶体结构为ZnO和MgO的混合结构。退火有利于薄膜结构的完善。3.溶胶-凝胶旋涂法制备的Mg_xZn_1-xO薄膜的发射光谱由峰值分别位于384nm、443nm和536nm附近的三个发射峰组成。石英玻璃衬底有利于紫外光发射,Si衬底有利于蓝光发射,薄膜的发光由缺陷能级引起。提高灼烧温度有利于提高薄膜样品的蓝光发射,退火使薄膜的紫外发光峰发生蓝移,蓝光发光峰发生红移。不同组分和不同衬底Mg_xZn_1-xO薄膜都具有紫外激发特性,Si衬底上激发光谱较宽。灼烧温度和退火对薄膜的激发光谱基本没有影响。Mg含量增加,薄膜的吸收边蓝移,带隙增大。退火也可以增大薄膜禁带宽度。4.射频磁控溅射法制备薄膜研究表明,当溅射功率为300W,气体流量为20sccm,靶与挡板间距为10mm,靶与衬底间距为80mm,衬底温度为室温,溅射时间为50min时获得高质量的薄膜样品。薄膜粒径分布均匀,随着溅射时间的增加,颗粒长大。蓝宝石衬底上薄膜的平均粒径最小约为10nm,Si衬底上薄膜的平均粒径最大约为40nm,薄膜为纳米膜。5.射频磁控溅射法制备的薄膜组分与靶材组分不一致,薄膜中Mg含量大于靶材中Mg含量。Si衬底上薄膜的组分为Mg_0.59Zn_0.41O,蓝宝石衬底上薄膜的组分为Mg_0.47Zn_0.53O,石英玻璃衬底上薄膜的组分为Mg_0.44Zn_0.56O,载玻片衬底上薄膜的组分为Mg_0.52Zn_0.48O。不同衬底上Mg_xZn_1-xO薄膜的结构均为ZnO的六方纤锌矿结构,薄膜具有c轴取向性。6.射频磁控溅射法制备的Mg_xZn_1-xO薄膜具有明显的吸收边,蓝宝石衬底上薄膜的吸收边位于292nm,石英玻璃和Si衬底上薄膜的吸收边位于298nm,载玻片衬底上薄膜的吸收边位于312nm,蓝宝石衬底和石英玻璃衬底Mg_xZn_1-xO薄膜的平均透过率达80%。薄膜的吸收边和发光峰随着溅射时间的增加发生蓝移。7.紫外探测器的响应截止边位于295nm,对应的光谱响应度R_λ为5.85A/W,外量子效率为2460.6%,NEP为1.681×10¹²W,D为5.95×10¹¹W^-1,D^*为1.78×10¹¹ cm·Hz·W^-1。日盲区响应峰值位于260nm,对应的光谱响应度R_λ为7.17A/W,外量子效率可达3421.8%,NEP为1.365×10¹²W,D为7.33×10¹¹ W^-1,D^*为2.2×10¹¹ cm·Hz·W^-1。8. Mg_xZn_1-xO粉体存在ZnO的六方纤锌矿和MgO的面心立方岩盐两种结构,当x小于0.20时,粉体为ZnO六方结构;当x大于0.80时,粉体为MgO立方面心结构,粉体随着灼烧温度的升高晶粒逐渐完善。采用粉体制备的Mg_xZn_1-xO陶瓷的透过率随x的变化而改变。更多还原

【Abstract】 Mg_xZn_1-xO Ternary compounds are a type ofⅡ-ⅥZnO based semiconductor material. The band gap of ZnO is about 3.3 and that of MgO is 7.8eV at room temperature. The band gap of Mg_xZn_1-xO film theoretically can be continuously adjustable from 3.3eV to 7.8eV, so that Mg_xZn_1-xO Ternary compounds have a wide application prospect in the UV, Visible emitting devices and solar blind region UV detectors. Mg_xZn_1-xO Ternary compounds become the hot spots of current research.In this thesis, Mg_xZn_1-xO thin film samples with various components were prepared on sapphire, quartz glass, Si and ceramic etc substrates by Sol-Gel spin-coating method and radio frequency magnetron sputtering （RFMS） method respectively. Components, structure and surface morphology were characterized with photoelectron energy dispersive spectroscope（EDS）, X-ray diffraction（XRD） and scanning electron microscope（SEM）. The properties of absorption, transmission and luminescence were studied by UV-visible spectrometer and UV-visible fluorescence spectrometer. The effects of fabrication conditions on the structure and optical properties of the film were discussed. A UV detector with MSM structure on Si （111） /Mg_xZn_1-xO was also prepared by lithography and wet chemical etching method and its properties ofⅠ-Ⅴand spectral responsivity were measured by hall test meter and spectral response measurement system. Mg_xZn_1-xO nanopowders were prepared by Sol-Gel method and Mg_xZn_1-xO ceramics were also prepared with the produced nanopowders. The properties of structure, luminescence, absorption and transmission of nanopowders and ceramics were characterized by XRD, UV-visible spectrometer and UV-visible fluorescence spectrometer. Main research results obtained are as follows:1. Results of film prepared by Sol-Gel spin-coating method indicate that high quality Mg_xZn_1-xO sol could be obtained under the conditions of acidic condition （pH value between 6.5-7.0）, temperature of the solution at 80℃, heating rate at 2-4℃/min, stabilizer at 0.3ml/g. Better samples of film were obtained by drying the sol at 120℃, then heating it at 300℃for 30min and calcined at 600℃for lh.2. The components of the film prepared by Sol-Gel spin-coating method and the components of design should be consistent. The structure of film changes with the x value. Mg_xZn_1-xO thin film is hexagonal ZnO structure with x≤0.33 while Mg_xZn_1-xO thin film is cubic MgO structure when x≥0.5. The crystal structure of the Mg_xZn_1-xO thin film is hybrid structure of ZnO and MgO when 0.33 <x <0.5. Annealing is conducive to improve the film structure.3. The emission spectra of Mg_xZn_1-xO thin film prepared by Sol-Gel spin-coating method was mainly composite of three emission peaks near at 384nm, 443nm and 536nm respectively. Quartz glass substrate is conducive to UV light emission, Si substrate is conducive to blue light emitting and the luminescence of thin film caused by the defect levels. Improving sintering temperature is conducive to the blue emission. Annealing makes UV emission peak of the film happen blue-shift and blue-ray emission peak happen red-shift. Mg_xZn_1-xO thin films with various components and on different substrates all have characteristics of UV excitation, while excitation spectrum on Si substrate is wider. Sintering temperature and annealing have no impact on excitation spectrum of thin film. With the content of Mg increased, absorption edge of the film blue shift and band gap increased. Annealing can also increases the band gap of film.4. Results of film prepared by RFMS method indicate that high quality film samples could be obtained under the conditions of sputtering power at 300W, gas flow at 20sccm, distance of target and baffle at 10mm, distance between target and substrate at 80mm, substrate temperature at room temperature, sputtering time at 50min. Particle size of film is homogeneous and particles grow up with the sputtering time increases. The smallest average particle size of film on sapphire substrates is about 10nm and the biggest average particle size of film on Si substrate is about 40nm. So the film is nanofilm.5. Components of film prepared by RFMS method are inconsistent with the target components and the content of Mg in film should be larger than the content of Mg in the target. The component of Mg_xZn_1-xO film on Si substrate is Mg_0.59Zn_0.41O. The component of Mg_xZn_1-xO film on sapphire substrate is Mg_0.47Zn_0.53O. The component of Mg_xZn_1-xO film on quartz glass substrate is Mg_0.44Zn_0.56O. The component of Mg_xZn_1-xO film on chip-carrier substrate is Mg_0.52Zn_0.48O. The structures of Mg_xZn_1-xO film on different substrates all were the hexagonal wurtzite structure of ZnO with c-axis oriention.6. Mg_xZn_1-xO film prepared by RFMS method has a clear absorption edge. The absorption edge of thin film on sapphire substrate is located at 292nm, absorption edges of thin films on quartz glass and Si substrate are located at 298nm and absorption edge of thin film on chip-carrier substrate locates at 312nm. The average transmittance of films on sapphire and quartz glass substrate is 80%. The absorption edge and luminescence peak of films blue shift with the sputtering time increases.7. The response cut-off edge of UV detector locates at 295nm corresponded to the spectral responsivity R_λis 5.85A/W. External quantum efficiency is 2460.6%, NEP is 1.681×10¹²W, D is 5.95×10¹¹W^-1, D^* is 1.78×10¹¹ cm·Hz·W^-1. The maximum response in the solar blind region locates at 260nm and corresponding spectral responsivity R_λis 7.17A/W. External quantum efficiency can be 3421.8%, NEP is 1.365×10¹²W, D is 7.33×10¹¹ W^-1, D^* is 2.2×10¹¹ cm·Hz·W^-1.8. Powder of Mg_xZn_1-xO exist two structures as the hexagonal wurtzite of ZnO and face-centered cubic rock salt structure of MgO. Mg_xZn_1-xO powder is the hexagonal structure of ZnO when x is less than 0.20,Mg_xZn_1-xO powder is face-centered cubic structure of MgO when x is greater than 0.80. The grain of powder has gradual improvement with the growing of sintering temperature. Transmittance of Mg_xZn_1-xO ceramic prepared by produced nanopowders change with the x value.更多还原