In this work, the possibility to control the chemistry of the initial growth of YSZ on Si was investigated, as well as the relationship between the chemistry and the resulting crystalline properties of the YSZ film. Both subjects were assessed by detailed study of the PLD growth process, with a focus on the contributions of the different sources of oxygen. In order to investigate these contributions, all sources were adressed individually:Background pressure. The contribution of oxygen from the background was varied by changing the partial oxygen pressure (pO2) at constant total pressures. Ar was used to reach the total pressure aimed for, since it is inert and has an atomic weight close to the weight of molecular oxygen. In this way, the plasma plume size and shape was kept similar, meaning the flux of oxygen from the background could be changed independently from the Zr and Y fluxes from the plasma. Additionally, the fluxes of Zr and Y from the plasma could be changed independently by changing the laser repetition rate.Plasma. The physics and chemistry of the plasma changes drastically with pressure22,24. For instance, the oxidation state of the plasma upon arriving at the substrate can be different for similar pO2, while the total pressure influences the arrival time and plasma temperature. For this reason, 2 different total pressures were examined, i.e. 2*10−2 and 1*10−1 mbar. The resulting physics and chemistry of the plasma were examined with self-emission spectroscopy.Native oxide. All 5 × 5 mm Si substrates were cut from the same 4 inch wafer in order to start with the same native oxide thicknesses in all experiments. However, the thickness can change due to heating of the substrate in the presence of oxygen. Therefore, in situ X-ray Photoelectron Spectroscopy (XPS) was used to determine silicon oxide thicknesses of the substrates in different deposition conditions.