锡掺杂量对胶体法制备ITO薄膜光电性能的影响

Effect of Sn-Doping Content on the Electrical and Optical Properties of ITO Films by Colloid Method

以金属铟和锡盐为原料采用胶体法制备Sn掺杂三氧化二铟（ITO）前驱物浆料，通过提拉法在镀有SiO2薄层的浮法玻璃基片上制备透明导电ITO薄膜。研究了不同Sn掺杂量5％～20％（质量分数，下同）对ITO薄膜光电性能的影响。用分光光度计和四探针电阻仪检测ITO薄膜，样品的光电性能，并对其进行X射线衍射分析。结果表明：当Sn掺杂量为10％时薄膜的方电阻最小，为153Ω／□，不同Sn掺杂的ITO膜均为单一的立方铁锰矿结构；薄膜在可见光区平均透过率≥82％。基于对不同Sn掺杂量的ITO薄膜XRD数据分析，研究了ITO薄膜的结构特性，并讨论了薄膜的导电机制。结果表明：胶体法制备的ITO薄膜的自由载流子主要来源于氧缺位提供的导电电子。通过对ITO薄膜吸收系数的线性拟合表明，薄膜中自由电子由价带至导带的跃迁属于直接跃迁，且光学能隙值随Sn掺杂量的增加呈先增加后减小的趋势，在Sn掺杂量为15％时为最大值3．65eV。

Transparent conductive ITO films （5 wt%-20wt% Sn-doped） were fabricated on soda lime float glass substrate by a colloid technique. The colloidal solutions were prepared from indium metal ingots and hydrous tin （IV） chloride. The electrical and optical properties of the ITO films were investigated by using the four-probe instrument and UV-VIS spectrophotometer. The results indicate that the ITO thin films containing 10 wt% Sn showed a minimum sheet resistance of 153 Ω/□, and the high transparent ITO thin films have been obtained in visible region. X-ray diffraction measurements were performed to determine the crystallinity of the ITO films to be polycrystalline with a cubic bixbyite structure. The lattice distortion of ITO films has been discussed based on their own XRD data respectively with tin doping concentration. The results indicate that the free carriers of these ITO films are attributed to the oxygen vacancies mostly. Linear simulation on absorptance near optical absorption edge of the ITO films indicates that the transition from valance band to conduction band is a direct transition. It was found that the optical band gap of the ITO thin films is dependent on the tin doping concentration and increases with increasing Sn content up to 15 wt%. The optical band gap of 15 wt% Sn content ITO films showed the maximal value of 3.65 eV, and after that it started to decrease.