Characteristics of ZnO thin films modified by various additives

Zinc oxide is a promising transparent conductive oxide (TCO) and there is unceasing interest in its optical and electrical properties for the last decades. In this paper, ZnO thin films modified by various additives such as erbium, vanadium and aluminum were fabricated using a sol-gel process and their electrical resistivity and surface morphology were investigated in terms of annealing conditions. Stable ZnO solutions containing different additives were synthesized by using 2-methoxyethanol as a solvent and monoethanolamine as a stabilizer. The electrical resistivity of ZnO films was found to be controlled by both doping concentration and annealing condition. Relatively lower electrical resistivity was achieved for the ZnO films doped with ~ 0.3 mol% Er, 0.3mol% Al or 0.03~0.1 mol % V after a post-annealing at 550 oC for 1 h in N2/H2. All the films deposited on glass exhibited very high transmittance of 90~97% within the visible wavelength region. This work was mainly focused on the overall pictures about the relationship between the electrical and optical performances and the processing variables such as doping species and concentrations.

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