High Temperature Durability Amorphous ITO:Yb Films Deposited by Magnetron Co-Sputtering

Yb-doped ITO (ITO:Yb) films were deposited on unheated non-alkali glass substrates by magnetron cosputtering using two cathodes (DC, RF) equipped with the ITO and $Yb_2O_3$ target, respectively. The composition of the ITO:Yb films was controlled by adjusting the RF powers from 0 W to 480 W in 120 W steps with the DC power fixed at 70 W. The ITO:Yb films had a higher crystallization temperature ($200^{\circ}C$) than that of the ITO films ($170^{\circ}C$), which was attributed to both larger ionic radius of $Yb^{3+}$ and higher bond enthalpy of $Yb_2O_3$, compared to ITO. This amorphous ITO:Yb film post-annealed at $170^{\circ}C$ showed a resistivity of $5.52{\times}10^{-4}{\Omega}cm$, indicating that a introduction of Yb increased resistivity of the ITO film. However, these amorphous ITO:Yb films showed a high etching rate, fine pattering property, and a very smooth surface morphology above the crystallization temperature of the amorphous ITO films (about $170^{\circ}C$). The transmittance of all films was >80% in the visible region.