Improved Mobility and Transmittance of Room-Temperature-Deposited Amorphous Indium Gallium Zinc Oxide (a-IGZO) Films with Low-Temperature Postfabrication Anneals

Thin films of amorphous indium gallium zinc oxide with high transmittance were deposited at room temperature onto flexible polymer substrates. Postdeposition anneals were performed at low temperatures in different ambients to obtain films with one of the highest transmittance and mobility values reported in the literature. As-deposited and postanneal films were characterized for electrical and optical properties. Oxygen anneal degraded the electrical performance of the films, which was recovered by succeeding vacuum anneals. A surface scattering model is proposed to determine the relation between mobility and carrier concentrations at low values of carrier concentrations. This model takes into account electronic scattering as a result of grain structure and morphology.