采用溶胶凝胶法旋涂制备了摩尔分数为3%的Li掺杂ZnO薄膜,在450~650℃下退火后测试其微结构、表面形貌和光电特性.结果表明薄膜为六方纤锌矿多晶结构且n型导电,退火温度的升高改善了结晶度、表面形貌、透过率和导电性.退火温度超过550℃后电阻率增大,样品由肖特基导电转变为欧姆导电;伏安特性模拟结果表明,替位Li逐渐增多、薄膜功函数增大,有利于制备p型薄膜.退火温度达600℃后,由于薄膜再蒸发等使光电特性变差.550℃是最佳退火温度,适于制备高质量的透明导电薄膜,此时薄膜透过率达95%,薄膜电阻率为2.49×103Ω.cm.%3 at. % Li-doped ZnO films were prepared by sol-gel spin-coating. The influence of post-annealing at 450- 650 ℃ on the film structural, optical and electrical properties was investigated. All the films show a polycrystalline hexagonal wurtzite structure and n-type conductivity. The rising annealing temperature facilitates the crystallization and improves the transmittance and conductivity. However, by annealing above 550 ℃, the film conductivity decreases and the oxide/electrode contacts change from the Schottky to ohmic type. The intrinsic reason is the supplantation of the interstitial Li-dopants by the substitutional ones and therefore the ZnO work function increases, as confirmed by the I-U simulating results. At annealing temperatures above 600 ℃, the samples are revaporised, resulting in poor optical-electrical properties. The optimum annealing temperature is 550 ℃ , with a transmittance of 95 % and a resistance of 2.49 × 10^3 Ω·cm, demonstrating the applicability of Li-doped ZnO as high-quality transparent conductive films.
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