A high ratio of Y/Zr to oxygen during growth caused formation of silicides, which could be tuned by changing the pO2 and the laser repetition rate. As shown for the case of a laser repetition rate of 14 Hz and a total pressure of 2*10−2 mbar, silicide formation occurred at pO2 below 1*10−5 mbar. At these conditions, plasma spectroscopy did not show any oxidation of the plasma. Initially, Y and Zr can take sufficient oxygen from the native oxide to form YSZ. However, oxygen deficiency may occur due to ongoing deposition of metal atoms. Oxygen deficiency makes YSZ unstable towards silicide formation when contacted with silicon31. In a pO2 of 1*10−5 mbar, the thermodynamically expected amount of vacancies is much lower than the amount causing instability31, while the flux of oxygen from the ambient should be sufficient to provide the necessary oxygen for complete oxidation of the growing film, considering the used growth speed (~0.5 unit cells per second at 14 Hz). Apparently, excess of O2 at the film surface is necessary to completely oxidize the film during growth.