Pulsed-magnetron-sputtered low-temperature indium tin oxide films for flat-panel display applications

In this paper, indium tin oxide (ITO) thin films were prepared by unipolar and bipolar direct current (DC)-pulsed magnetron sputtering in a mixture of argon and oxygen onto unheated glass substrates. The target of ITO with 10 wt.% tin is used. The influences of polar modes (unipolar and bipolar); output frequencies (0 to 33 kHz); and times and off times on the optical, electrical, and structural properties of ITO films are investigated. The correlations between the deposition parameters and the film properties are discussed. It is found that the resistivity with 10-3 Ω-cm and transmittance with ≥90% of amorphous ITO films can be prepared by the reactive bipolar DC-pulsed sputtering with t-on between 45 µs and 85 µs (i.e., t-on/t+on is 9-17), and t+on, t-off and t+off are constant at 5 µs, 10 µs, and 5 µs, respectively. An optimal condition, based on the polar mode and frequency of reactive-pulsed sputtering, for obtaining the high transmittance and low resistivity of ITO films is suggested.