Effect of Sputtered Current Ratio on Titanium Aluminum Nitride Films under DC Reactive Magnetron Co-Sputtering

Abstract

Titanium aluminum nitride thin films were prepared by DC reactive magnetron co-sputtering. Titanium and aluminum were used as sputtering targets. Deposition occurred under argon and nitrogen gases ambient with the flow rates of 4.0 and 2.5 sccm, respectively. Films were deposited under the changing of sputtering current for Ti and Al targets. It is found that when the sum of the sputtered currents of the Ti and Al targets is the same, the film thickness is nearby similar. The element of Ti in the film increased as the sputtered current of Ti increased, resulting in a lower percentage of transmittance because Ti showed a good absorption film. Under the Ti/Al ratio of 1.31/1.00, the normal solar transmittance percentage (Tavg) was 61.01 %. In contrast, the higher Al content showed a higher light transmittance. Under a condition of coating the film with the sputtered current of Ti of 500 mA and Al of 400 mA, the film had a high light transmittance percentage. When the coating time was increased, the thickness of the film was also increased, and surface structure was induced to be greater grain size with columnar structure. With the coating times of 15, 30 and 60 min, the average grain sizes were 28, 46 and 57 nm, respectively, the average thicknesses were 196, 268 and 357 nm, respectively, and Tavg were 73.01 54.70 and 25.97 %, respectively. The film with a coating time of 60 min was formed in the crystal structure of TiAlN for (111), (200) and (200) plane. Under this coating condition, it is suggested that the films are suitable for further application with their optical and structural properties.