Highly conductive and transparent In-doped zinc oxide thin films deposited by chemical spray using Zn(C₅H₇O₂)₂

Abstract

Highly conductive and transparent indium-doped zinc oxide, ZnO, thin films were deposited on sodocalcic glass substrates by chemical spray, using zinc acetylacetonate, Zn(C₅H₇O₂)₂, and doped with indium chloride. Substrate temperature, dopant concentration in the starting solution and the kind of alcohol used as a solvent (methanol, ethanol and isopropanol) were varied in order to optimize deposition conditions. The lowest resistivity value of $2.8x10^{ - 3} \Omega - cm$ was obtained with ethanol at a substrate temperature of 475 °C and a [In]/[Zn]=2.5 at % ratio in the starting solution. The mobility and the carrier concentration values were in the order of $6cm^2 /\left( {V - s} \right)$ and $10^{20} cm^{ - 3}$, respectively. For optimal deposition conditions no preferential growth was found. Surface morphology was altered depending on the kind of alcohol used, producing a rough surface with isopropanol than with methanol or ethanol. Transmittance average was of the order of 85%, at 550 nm.