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

Publication date: 31 December 2015
Source:Thin Solid Films, Volume 597
Author(s): Takahiro Shirahata, Toshiyuki Kawaharamura, Shizuo Fujita, Hiroyuki Orita
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 Ωcm 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 Ωcm and transmittance higher than 90%, despite the use of a non-vacuum-based open-air technology.