Photoelectron spectroscopic analysis of Hf-silicate/SiO2∕Si stacks deposited by atomic layer chemical vapor deposition

Hf-silicate/SiO2 bilayers were grown on Si(100) by atomic layer chemical vapor deposition. High-resolution transmission electron microscopy and atomic force microscopy images of Hf-silicate/SiO2∕Si samples showed very flat interfaces and uniform amorphous characteristics. Unlike Hf-silicate/Si samples, Hf-rich silicate phases or Hf-silicide dislocations were not observed in Hf-silicate/SiO2∕Si samples. The valence band offset (ΔEV) was increased from 3.26 (Hf-silicate) to 4.23eV (SiO2 buffer layer). These SiO2 buffer layer effects were strongly related to the decrease of leakage current in Hf-silicate/SiO2 films compared to Hf-silicate films.