Transparent conductive zinc-oxide-based films grown at low temperature by mist chemical vapor deposition

Atmospheric pressure mist chemical vapor deposition (Mist–CVD) systems have been developed to grow zinc-oxide-based (ZnO-based) transparent conductive oxide (TCO) films. Low-resistive aluminum-doped ZnO (AZO) TCOs, showing resistivity of the order on 10⁻⁴ Ωcm, previously were grown using a safe source material zinc acetate [Zn(ac)₂], at a growth temperature as high as 500 °C. To grow superior TCOs at lower temperatures, we proposed the addition of NH₃ to accelerate the reaction of acetylacetonate compounds. As the result, we could grow gallium-doped ZnO (GZO) TCOs with a resistivity of 2.7 × 10⁻³ Ω cm and transmittance higher than 90% at 300 °C by using zinc acetylacetonate [Zn(acac)₂] as the Zn source. To grow boron-doped ZnO (BZO) TCOs at a lower growth temperature of 200 °C, we used boron doping along with a toluene solution of diethylzinc (DEZ), that maintained high reactivity without being flammable. These BZO TCOs showed a resistivity of 1.5 × 10⁻³ Ω cm and transmittance higher than 90%, despite the use of a non-vacuum-based open-air technology. - Highlights: • Introduction of Mist–CVD as a non-vacuum-based, safe, and cost-effective growth technology • Process evolution of the growth technology to lower the growth temperature. • Achievement of low resistive ZnO films at 200oC.