The deposition of Ir/YSZ double-layer thin films on silicon by PLD and magnetron sputtering: Growth kinetics and the effects of oxygen

This work focuses on the epitaxial growth process and kinetics of silicon-based Ir/yttria-stabilized zirconia (YSZ) bilayer films prepared by PLD and magnetron sputtering, including the sequential growth of a YSZ film, an Ir seed layer, and an Ir film on a silicon substrate. The results show that for growing YSZ films by PLD at the target-to-substrate distance of 60 mm, the higher the laser energy density and the oxygen pressure, the lower the laser frequency, the higher the epitaxy quality. In addition, for the preparation of the Ir-seed layer by PLD, background gas decelerates the plasma and suppresses self-sputtering and implantation, which is beneficial to obtaining a high-quality seed layer. In particular, introducing a small amount of oxygen is able to improve the epitaxial quality of the films during the growth of Ir-seed and Ir films, and the mechanism of oxygen is proposed. For the growth of Ir films by magnetron sputtering, the growth rate and the energy of argon ions increased with the increase of RF power, while the epitaxial quality is the opposite. The kinetic theory and simulation results demonstrate that this trend is mainly caused by the increase in the number of particles reaching the substrate without significantly increasing the distribution of high-energy particles. Finally, high-quality Ir (1 0 0) films on the YSZ (1 0 0) with a fresh surface are prepared. It is shown that increasing the epitaxy quality of the YSZ (1 0 0) film and the growth temperature of the Ir film can improve the quality of Ir film. Based on our results, the growth of Ir films on YSZ films with fresh surfaces resulting from in-situ argon plasma cleaning provides a new idea for preparing Ir (1 0 0)/YSZ (1 0 0) bilayer epitaxial film.