Optical and Electrical Properties of Transparent Conductive NTTO/Cu/NTTO Multilayer Films Deposited by Magnetron Sputtering

Nb/Ta-codoped TiO2 (NTTO)/Cu/NTTO (TCT) multilayers formed from two NTTO layers with a Cu interlayer have been deposited by magnetron sputtering on glass substrates for possible use as transparent conductive films. The variations in the growth, structure, and optical and electrical properties of the TCT samples were investigated as a function of the thickness of the Cu layer (dCu). The results show that the crystallinity of the top NTTO film is controlled by dCu. The critical thickness of the Cu layer for the formation of a continuous structure is about 11 nm, which is also the inflection point of the visible transmittance. As dCu was increased from 0 nm to 23 nm, the electrical resistivity of the TCT film decreased from 2.7 × 10−3 Ω cm to 5.6 × 10−5 Ω cm. The TCT multilayer with a 16-nm Cu interlayer showed a sheet resistance of 6.7 Ω/sq, an average visible transmittance of 80%, and an optimum figure of merit of 3.0 × 10−2 Ω−1.