A study of the laser-aided TVA plasma applied for deposition of Mg/Zn:Al bilayers

In this study we present the deposition of Mg/Zn:Al bilayers by using of laser-supported Thermionic Vacuum Arc (TVA) technique. Since the arc discharge in the TVA system glows in the vapors of deposited materials the obtained films are characterized by high purity. Additionally, higher deposition rate is achieved in TVA system compared to e.g., magnetron deposition. The bilayer structures were formed by the subsequent deposition of magnesium, followed by a zinc/aluminium mixture with 99.99 % purity grains in a ratio of 4:1 in the graphite crucible, which was used as the anode in the TVA system. The TVA discharge power was typically tens of watts. A diagnostic system comprising a double probe heated by a DC current was used to measure the plasma parameters in the course of the deposition process. Since double probe is a floating system, its data is less susceptible to be influenced by possible plasma instabilities. The double probe data acquisition was computer-controlled since the amount of material in the crucible allowed for rather short run of one experiment, approximately 10 minutes. Measurements without and with the laser action suggested effect of the laser on the plasma electron density and temperature when the plasma density was close to the 10 16 m -3 order of magnitude of the electron density or less. Standard surface analysis methods such as XRD, SEM, EDX were applied for characterization of the deposited films. The laser induces fast crystallization process on the substrate along c-axis. In case of Zn:Al, the SEM images (3D) show a columnar grow of the hexagonal zinc structures that can be identified with a textured structure. Even if we cannot explain the laser effect in detail, it seems that it induces an increase of the kinetic energy of the plasma components, which in turn result in a fast crystallization process. • application of a heated double probe for diagnostic of LTVA plasma in Mg, Zn and Al vapors, • (ii) measured effect of green (532 nm) laser on electron energy distribution function • (iii) estimated effect of green (532 nm) laser on crystallization of Mg film deposited by LTVA.