Nanoparticle Synthesis by Hollow Cathode Sputtering using High-Power Pulsed Plasmas

U. Helmersson, R. Gunnarsson, S. Ekeroth, D. Söderström, I. Pilch, N. Brenning
Linköping University, SE

Keywords: nanoparticles, plasma


Pulsing a plasma source using high-power is an efficient means to ionize the supplied gases and sputtered source material. The advantage of ionizing the source material is that it increases the probability of trapping positively charged ions onto negatively charged nanoparticles in the plasma, resulting in a significant increase in the growth rate and utilization of material. In this work, cylindrical metal hollow (5 mm) cathodes of Cu, Ti, Ag, In, Fe, Mn and Mo were used as targets where sputtering occurs on the inside surface of the cylinder. Preliminary results using a linear (5 mm x 80 mm) hollow cathode of Cu will also be presented. Figure 1 illustrates a conceptual idea for a production line using a linear hollow cathode source together with a photograph of an ignited linear source. Sputtering was performed using Ar (primarily) as the working gas. TiO2, TiN and In-Al-N compound nanoparticles were synthesized by adding O2 or N2 gases. Figure 2 illustrates examples of nanoparticles produced with a pulsed hollow cathode, which demonstrates the flexibility of the method. The nanoparticles grown in the plasma were deposited directly upon conducting (Ti coated Si) or insulating substrates (glass or oxidized Si).