Yttrium oxide thin films have been deposited on Si （100） substrate by using pulsed laser deposition （PLD） method. X-ray diffraction （XRD）, hard and soft X-ray absorption spectroscopy （XAFS） are employed to investigate the origin of oxygen vacancies and their influence on the structure and atomic distributions. The XRD results indicate that the Y203 thin films strongly orient the （111） axis of the cubic structure. Analyses on the Y K-edge extended X-ray absorption fine structures reveal that the coordination number of Y atoms decreases and the bond length of Y-O contracts due to the loss of oxygen atoms. The X-ray absorption near edge structure analysis together with a theoretical approach further confirms the oxygen vacancies formation and their possible location.
Abstract： Amorphous LazHf2O7 films were grown on Si（100） by pulsed laser deposition method. The valence and conduction band offsets between amorphous La2Hf2O7 film and silicon were determined by using synchrotron radiation photoemission spectroscopy. The energy band gap of amorphous La2Hf2O7 film was measured from the energy-loss spectra of O ls photoelectrons. The band gap of amorphous LazHf2O7 film was determined to be 5.4±0.2 eV. The valence and the conduction-band offsets of amorphous La2Hf2O7 film to Si were obtained to be 2.7±0.2 and 1.6±0.2 eV, respectively. These results indieated that the amorphous La2Hf2O7 film could be one promising candidate for high-k gate dielectrics.
Amorphous La2Hf2O7 thin films were deposited on Si（100） substrate by pulsed laser deposition （PLD） method under different con-ditions. The interfacial states of the La2Hf2O7/Si films were studied by synchrotron X-ray reflectivity （XRR） and X-ray photoelectron spec-troscopy （XPS）. When grown under vacuum condition, silicate, silicide and few SiOx were formed in the interface layer. However, the Hf-silicide formation could be effectively eliminated by the ambient oxygen pressure during film growth. The result revealed that the La2Hf2O7/Si interlayer was intimately related with growth condition. Insufficient supply of oxygen would cause Hf-silicide formation at the interface and it could be most effectively controlled by the ambient oxygen pressure during film growth.
