In situ photoemission study on initial growth of HfO2 films on Si(1Â 0Â 0)

Ultrathin HfO2 films were deposited on a Si substrate at 25 °C and 350 °C by electron-beam (e-beam) evaporation using a metallic source in an O2 pressure of 2 × 10−7 Torr. In situ synchrotron radiation photoelectron spectroscopy (SRPES) was used to investigate the chemistry of HfO2 films on Si(1 0 0) at the initial growth stage. Si-rich silicates are found at the interfaces of HfO2/Si grown at both 25 °C and 350 °C, whereas a small portion of Hf-suboxides are also observed for the sample grown at 25 °C. The formation of interface layers at such a low O2 pressure, which are mainly composed of Si-rich silicates, is attributed to the Hf atom catalytic oxidation effect.