F-doped ZnO by sol-gel spin-coating as a transparent conducting thin film

This paper reports a simple non-alkoxide sol-gel route for depositing F-doped ZnO thin film on glass substrates. Ammonium fluoride and zinc acetate were used as the dopant precursor and starting material for ZnO, respectively. After the first crystallization at 550°C in air, the sol-gel spin coated ZnO:F thin films at a F concentration < 5 at. % showed a nanosized polycrystalline structure with a c-plane preferred orientation. The structures, electrical resistivity, carrier concentration, mobility and optical transmittance were strongly dependent on the F concentration. The F concentration > 5 at. % degraded the microstructures, electrical conductivity, and optical transmittance. The second post-heat-treatment at 450°C in a reducing environment resulted in higher electrical resistivity than the first post-heat-treatment in air.