【作者】 龚丽；

【导师】 叶志镇； 吕建国；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2011， 博士

【摘要】 ZnO作为直接宽禁带化合物半导体,由于原料丰富、价格低,有望取代GaN应用于短波长光电器件。如果能同时实现掺杂和能带工程,制备p型ZnMgO薄膜,不仅可以提高发光二极管的发光效率,而且可以拓宽其工作波长。所以本文通过In-N共掺制备了p型ZnMgO薄膜。ZnO可见光透过率超过90%,天然为n型,通过掺Ga、Al等ⅢA族元素能够提高薄膜导电性能。ZnO具有无毒、价格低、在H中稳定等优点,有望取代ITO。本文开展了Al、Ga掺杂ZnO透明导电膜的研究。现在电子器件逐渐朝柔性化方向发展,使得对柔性透明导电膜的需求日益迫切。因此,开发光电性能优良的柔性透明导电膜具有非常现实的意义。本文继而在聚合物PC衬底上制备Ga掺杂ZnO基透明导电膜。主要工作包括以下内容：1.采用直流反应磁控溅射法In-N共掺技术实现ZnMgO薄膜的p型转变,研究了N20分压和Mg含量对薄膜性能的影响。研究发现,在合适的N20分压下,可以获得良好的p型导电性能。通过XPS测试,发现了对应N-Zn键的峰位和对应In-N键的峰位,证实施主-受主共掺是可行的。通过XRD和XPS测试结果,发现Mg在薄膜中以Mgzn形式存在。利用In-N共掺p-ZnMgO薄膜和In掺杂1n-ZnMgO薄膜制备了同质p-n结,I-V性能测试显示出典型的整流特性。2.采用脉冲激光沉积法在玻璃衬底上生长了Al掺杂ZnO薄膜,研究了衬底温度对薄膜性能的影响。当衬底温度为350℃时,获得了透明的高导电近红外反射薄膜,这种薄膜在近红外反射镜和热反射器等领域具有广阔的应用前景。3.采用射频磁控溅射法在PC衬底上生长了Ga掺杂ZnO(GZO)薄膜,研究了氧分压和溅射压强对薄膜性能的影响。薄膜获得的最低电阻率为7.8×104Ωcm,在可见光的平均透过率超过80%。4.为了克服聚合物的各种缺点,在沉积GZO之前引入ZnO缓冲层。为了在实验次数较少的情况下,获得较好的实验结果,我们采用正交分析法综合研究了溅射功率、溅射压强、溅射时间、氧分压比等生长参数对GZO/ZnO膜可见光透过率和电阻率的影响。通过极差分析得到最优生长参数。与未引入缓冲层的GZO膜相比,最优参数下制备的GZO/ZnO膜的电阻率由7.85×104Ωcm减小为5.21×104Ωcm。由于厚度效应,薄膜的透过率有所下降,但不是很明显,还是能够满足器件的应用要求。5.多层结构透明导电膜的研究。与单层ZnO膜相比,多层膜更薄,导电性更优。与单层金属膜相比,多层膜透过率更优。主要研究了Cu层厚度和GZO层厚度对GZO/Cu和GZO/Cu/GZO多层膜性能的影响。GZO(30nm)/Cu(12nm)表现最佳性能指(?)ΥC为4.66×10-3Ω-1。GZO(10 nm)/Cu(10 nm)/GZO(10 nm)表现最佳性能指(?)ΥC为4.66×10-3Ω-1,其在1000～2500 nm波长范围内的平均反射率为70%,这种具有较好近红外反射特性的薄膜在近红外反射镜和热反射器等领域具有广阔的应用前景。更多还原

【Abstract】 ZnO is a direct wide band-gap compound semiconductor. Due to abundant material and low cost, ZnO is considered as a promising material instead of GaN for short-wavelength optoelectronic devices. If the doping engineering and the bandgap engineering are meanwhile realized, namely p-type ZnMgO is prepared, luminous efficiency of light-emitting diodes (LEDs) can be improved and the working waveband can be modulated. In this paper, p-type ZnMgO thin films were realized by In-N codoping method.The transmittance in the visible range for ZnO thin films is over 90 %. Undoped ZnO is n-type conductive. And the conductivity of ZnO films can be improved by doping IIIA group elements such as Ga, Al and so on. Compared with Sn doped In2O3 (ITO), ZnO has several merits, such as innoxious, cheap, stable in H. So ZnO is considered as a promising candidate for substituting ITO. In this paper, we investigated the properties of Al-and Ga-doped ZnO transparent conductive films. Nowadays, many electronic devices become flexible, which claims that transparent conductive oxide (TCO) films must be flexible. Therefore, it is practical to prepare flexible TCO films with good optical and electrical properties. So we also investigated the properties of Ga-doped ZnO (GZO) transparent conductive films on polycarbonate (PC) substrates. The work included:1. In-N codoped ZnMgO films have been prepared on glass substrates by direct current reactive magnetron sputtering. We investigated the effect of N2O partial pressures and Mg contents in the targets on the properties of ZnMgO thin films. The p-type conductivity could be obtained in ZnMgO films by adjusting the N2O partial pressures. The presence of In-N and Zn-N bonds was identified by x-ray photoelectron spectroscopy (XPS), which may enhance the nitrogen incorporation and respond for the realization of good p-type behavior in In-N codoped ZnMgO films. According to the analysis results of XPS and x-ray diffraction (XRD), we found that Mg substituted Zn in the crystal lattice. The ZnMgO-based p-n homojunction was fabricated by deposition of an In-doped n-type ZnMgO layer on an In-N codoped p-type ZnMgO. The p-n homostructural diode exhibits electrical rectification behavior of a typical p-n junction.2. Al-doped ZnO (AZO) thin films have been prepared on glass substrates by pulsed laser deposition. The properties of films were strongly dependent on the growth temperatures. When the temperature was 350℃, we obtained tansparent. conductive and near infrared (IR) reflective thin films. The good IR-reflective properties of AZO films show that they are promising for near-IR reflecting mirrors and heat reflectors.3. GZO thin films have been prepared on PC substrates by radio frequency magnetron sputtering. The dependence of the properties of films on the sputtering pressures and the oxygen partial pressures was investigated. The lowest resistivity of 7.8x10-4 Qcm was obtained. The average transmittance in the visible light range of all the films was over 80%.4. In order to conquer the disadvantages of polymer substrates, a ZnO buffer layer is necessary to be used before that GZO films are deposited on polymer substrates, which will make the polymer surface smoother and reduce diffusion of vapor and oxygen. In order to optimize the design of ZnO buffer layer deposition process, the Taguchi experimental design was used. We investigated the effect of sputtering power, sputtering pressure, sputtering time and the O2 partial pressure ratio on the optical properties in the visible light range and the resistivity for the GZO thin films deposited on PC substrates with undoped ZnO layers. The optimal parameters of the ZnO buffer layer could be obtained according to the range analysis method. Compared with the single layer GZO films, the electrical resistivity of GZO/ZnO films decreased from 7.85×10-4Ωcm to 5.21xlO-4 Qcm. Due to the thickness effect, the transmittance of the GZO film with the ZnO buffer layer is lower than that of the GZO film without the ZnO buffer layer, which is high and acceptable for applications.5. We also investigated the properties of multilayer structure TCO films. According to the single layer ZnO TCO films, multilayers are thinner and more conductive. According to the single layer metal films, multilayers are more transparent. We mainly investigated the effect of Cu layer thickness and GZO layer thickness on the properties of GZO/Cu and GZO/Cu/GZO multilayers. The highest figure of meritφTC is 4.66x10-3Ω-1 for the GZO(30 nm)/Cu(12 nm) multilayer. The highest value of figure of merit (φTC is 2.68x10-3Ω-1 for the GZO(10 nm)/Cu(10 nm)/GZO(10 nm) multilayer. The highest average near infrared reflectivity in the wavelength range 1000-2500 nm is as high as 70 % for the GZO(10 nm)/Cu(10 nm)/GZO(10 nm) multilayer. The good IR-reflective properties of GZO/Cu/GZO multilayers show that they are promising for near-IR reflecting mirrors and heat reflectors.更多还原