Uniformity in large area ZnO:Al films prepared by reactive midfrequency magnetron sputtering

Al-doped zinc oxide (ZnO:Al) films were deposited on glass substrates using a reactive midfrequency magnetron sputtering process. The optical transmission and reflection as well as the electrical resistivity of the films prepared on an area of 1000X600 mm(2) were determined at different locations. Films with a uniform distribution of resistivity between 2.9X10(-4) and 3.6X10(-4) Ohm cm and transmittance up to 88% in the visible spectral range were obtained. The ellipsometric spectra of the films were also analyzed using the Drude-Lorentz model, The calculated thicknesses of the films agreed well with those measured by a step profilometer. Secondary neutral mass spectrometry depth profiling showed uniform contents of Zn and O elements, while a slight periodic variation of the Al content was observed at different depths inside the film. A transition zone of 35-55 nm in width between the films and glass substrates due to the interdiffusion was also observed. (C) 2002 American Vacuum Society.