Super-smooth indium–tin oxide thin films by negative sputter ion beam technology

An ionized physical vapor deposition, negative sputter ion beam (NSIB) technology, is described for the deposition of super-smooth indium–tin oxide (ITO) thin films with highly transparent and conductive properties at near-room temperature deposition. A negatively charged sputter ion beam is produced by retrofitting an ITO magnetron sputtering cathode with a cesium vapor injector capable of releasing controlled amounts of cesium vapor into the plasma during deposition. Using this highly energetic deposition process, ITO thin films have been obtained at near-room temperature (less than 50 °C) with super-smooth surface (<1 nm rms), resistivity of 4×10−4 Ω cm, and transmittance higher than 85% (at wavelength 550 nm) on polycarbonate substrates.