关键词: 溶胶凝胶法, ZnO薄膜, Li掺杂, 退火温度, 光电特性

Abstract: 3 at.% Li-doped ZnO films were prepared by sol-gel spin-coating. The influence of post-annealing at 450~650°C 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°C, 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°C, the samples are revaporised, resulting in poor optical-electrical properties. The optimum annealing temperature is 550°C, with a transmittance of 95% and a resistance of 2.49×10³ Ω·cm, demonstrating the applicability of Li-doped ZnO as high-quality transparent conductive films.