Band offset and interface chemistry of HfO2/Si (001) prepared by electron‐beam evaporation in ultrahigh vacuum using atomic oxygen

Abstract

AbstractThe band offset and interface chemistry of HfO2 films prepared by ultrahigh‐vacuum electron‐beam evaporation was investigated by synchrotron radiation photon electron spectroscopy (SRPES). A relatively large valence band (VB) offset of the HfO2 film with Si was determined to be 3.56 eV. Both the Hf‐silicate and a small number of HfSi bonds were formed at the interface of HfO2/Si. This HfSi bond, which cannot be prevented completely in an ultrahigh‐vacuum preparation system using the Hf metallic source despite the atomic oxygen source adopted, may be mainly responsible for this large value of VB offset of HfO2/Si(001). This result also suggests that metal–silicon bonds at the interface of high k oxides on Si may generally lead to a larger VB offset than that with all silicon atoms at the interface bonding directly with oxygen.