The work described above shows the occurance and importance of several chemical processes during initial growth of YSZ on Si by PLD, e.g. silicon oxide reduction and silicide formation. However, limited attention has been paid to the possibilities to control these different chemical processes. An unique feature of the PLD process is the interaction of the plasma with the background gasses present in the deposition chamber. The metals in the plasma can obtain different degrees of oxidation depending on the partial oxygen pressure22. As shown for the homoepitaxial growth of SrTiO3 (STO), stoichiometry and growth kinetics depend heavily on the degree of oxidation of the plasma. Furthermore, the STO substrate proved to supply oxygen to the growing STO film as well23. Similar to the growth of STO on STO, three sources of oxygen can be distinghuised during growth of YSZ on Si with native oxide. At the substrate/film surface, oxygen can arrive from the plasma as atomic or molecular oxygen, or in the form of (partially) oxidized zirconium and yttrium. The oxygen from the background can oxidize the growing film directly, but also interact with the plasma. Furthermore, oxygen is present in the silicon native oxide. The thickness of this oxide can change during heating to the YSZ growth temperature due to reaction with oxygen from the background. Since oxygen is involved in all of the chemical processes described before, tuning the contributions of all sources of oxygen may provide a way to control the chemistry during the scavenging process.