新型ZnO基透明导电氧化物薄膜的研究

【作者】 吴臣国；

【导师】 沈杰；

【作者基本信息】 复旦大学 ， 物理电子学， 2010， 硕士

【摘要】 本文采用直流磁控反应溅射金属镶嵌靶Zn/Mo和Zn/W制备了高价态差掺钼氧化锌(ZnO:Mo, ZMO)和掺钨氧化锌(ZnO:W, ZWO)透明导电薄膜,研究了掺杂浓度、氧分压、溅射电流、基板温度等制备参数对ZMO和ZWO的薄膜结构、电学和光学性能的影响；利用XRD、AFM、XPS、分光光度计、太赫兹(THz)透射谱等分析手段对薄膜进行表征与分析；制备了结晶性良好、载流子迁移率高的ZMO和ZWO薄膜。直流磁控反应溅射金属靶制备的ZMO透明导电薄膜为多晶的六角纤锌矿结构；获得了直流磁控溅射法制备具有良好光电特性的ZMO薄膜的最佳工艺条件；制得的ZMO薄膜的最低电阻率为7.9×10-4Ω·cm,相应载流子迁移率为27.3cm2V-1s-1,载流子浓度为3.1×1020cm-3；在可见光区(400-700 nm)的平均透射率为85%,折射率(550nm)为1.853,消光系数为7.0×10-3。研究表明,氧分压对制备薄膜的光电特性有很大影响,通过改变氧分压可以调节薄膜载流子浓度,同时禁带宽度随载流子浓度的增加由3.37eV增大到3.8eV,并测得载流子有效质量m’为0.33倍的电子质量。采用直流磁控反应溅射方法,通过调节氧分压在玻璃基底上制备了不同载流子浓度的ZMO透明导电薄膜。首次应用太赫兹时域光谱技术研究了ZMO导电膜的太赫兹透射性质及介电响应,得到了电导率和薄膜折射率的频谱,实验结果很好地与经典Drude模型相吻合。ZMO导电膜的太赫兹脉冲透射性质表明通过调节ZMO薄膜的载流子浓度,该导电膜可作为太赫兹频率范围的光学器件的宽带抗反射涂层。本文还采用直流磁控溅射法制备了ZWO薄膜。在ZWO薄膜中,W原子替代了ZnO晶格中的Zn原子的位置,没有形成新的化合物,也没有改变ZnO的六角纤锌矿晶格结构。获得的ZWO薄膜的最低电阻率为6×10-3Ω·cm,在可见光区(400-700nm)的平均透射率为86%。研究表明,ZWO多晶薄膜的电学与光学特性与掺杂量、氧分压、基底温度以及溅射电流等制备条件参数密切相关。更多还原

【Abstract】 Transparent conductive oxide films of both ZnO:Mo (ZMO) and ZnO:W (ZWO) have been successfully fabricated by using DC reactive magnetron sputtering from metallic targets of Zn/Mo and Zn/W, respectively. The dependence of electrical, optical and structure properties of both ZMO and ZWO films on deposition parameters, such as Mo-doping content, oxygen partial pressure, and substrate temperature, have been investigated in detail. The structure, surface morphology, chemical state properties, terahertz transmission of ZMO films were studied by XRD, AFM, XPS and terahertz spectroscopy, respectively.ZMO transparent conductive thin films prepared by DC reactive magnetron sputtering on glass substrates from metallic targets were polycrystalline with the hexagonal crystal structure. The experimental condition of DC magnetron sputtering for ZMO films with good optical and electric properties has been established. The minimum resistivity of 7.9×10-4Ω·cm is obtained, with a carrier mobility of 27.3 cm2V-1s-1 and a carrier concentration of 3.1×1020 cm-3, and the average transmittance is about 85% in the visible light region. The refractive index and extinction coefficient at the wavelength of 550 nm are 1.853 and 7.0×10-3, respectively. The results show that oxygen partial pressure greatly effects on the photoelectricity of ZMO thin films, and the carrier concentrationgs of the films could be adjusted by controlling the oxygen partial pressure. The energy bands increase from 3.37 eV to 3.8 eV with the carrier concentrations augment and the carrier effective mass m* is 0.33 times as the electron mass.With DC reactive magnetron sputtering method, transparent conducting molybdenum-doped ZnO thin films with different carrier concentration on glass substrate were fabricated by monitoring oxygen partial pressure. The dielectric responses of the ZMO films are characterized with terahertz time-domain spectroscopy. Frequency dependent conductivity, power absorption, and refractive index are obtained, and the experimental results can be well reproduced with classic Drude model. Our results reveal that, by adjusting the carrier concentration of ZMO film, the conducting ZMO film can serve as broadband antireflection coatings for substrates and optics in terahertz frequency range.ZWO films have been also successfully fabricated firstly by using DC reactive magnetron sputtering from metallic targets of Zn/W. ZWO films are polycrystalline with the hexagonal crystal structure. The lowest electrical resistivity of ZWO films was 6×10-3Ω·cm and the average visible transmittance of the ZWO film was 86%. The results show that electrical, optical and structure properties of ZWO films depend on sputtering parameters such as oxygen partial pressure, doping content, substrate temperature and sputtering current, etc.更多还原