pH值对溶胶-凝胶法制备的掺铝氧化锌薄膜光电性能的影响

Effect of pH Value on the Optical and Electrical Properties of Al-doped ZnO Thin Films by Sol-gel Process

采用溶胶-凝胶法在普通载玻片上制备出c轴择优取向的ZnO∶Al(ZAO)透明导电薄膜,研究了溶胶pH值对其结构、表面形貌、电学和光学性能的影响。结果表明:随着pH值的降低晶粒尺寸增大;当溶胶pH值从8.4降低到6.8时,薄膜的电阻率先降低而后略有升高,当pH值为7.2时其电阻率达到最小值2.6×10-3Ω.cm,进一步分析表明,溶胶pH值的变化影响了薄膜晶界散射,而后者又使载流子迁移率发生了变化;薄膜的透光率在可见光部分随着pH值的降低而升高,而禁带宽度则从3.36 eV降到3.32 eV。

Al-doped ZnO transparent conducting thin films oriented along the c-axis have been prepared by sol-gel process on glasses and the effect of pH value of precursor sol on the microstructures, surface morphologies, electrical and optical properties of thin films was investigated. The results show that the grain sizes of films increase with the decrease of pH value of the precursor sol, the resistivities decrease at first and then increase with decrease of pH value from 8.4 to 6.8, and the minimum resistivity is obtained at the pH = 7.2. Further analysis indicated that the variation of pH value of the precursor sol results in the change of carrier mobility which is relative to the grain boundary scattering. Within the visible wavelength region, the transmission of the films increased as the pH value decrease, while the band gap decrease from 3.36 eV to 3.32 eV.