AVS 51st International Symposium
    Dielectrics Monday Sessions
       Session DI-MoP

Paper DI-MoP7
Valence Band Offsets and Interface Structure of Hf@sub X@si@sub 1-X@o@sub 2@ Films on Si(111) from Photoemission Spectroscopy

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: L. Fleming, North Carolina State University
Authors: L. Fleming, North Carolina State University
M.D. Ulrich, Army Research Office
C. Hinkle, North Carolina State University
J.G. Hong, North Carolina State University
J.E. Rowe, University of North Carolina
G. Lucovsky, North Carolina State University
A.S.-Y. Chan, Rutgers University
T.E. Madey, Rutgers University
Correspondent: Click to Email
We have used synchrotron radiation to perform high resolution soft x-ray photoemission spectroscopy measurements on device-quality Si(111)/Hf@sub x@Si@sub 1-x@O@sub 2@ films. Our samples included both thick (~ 75 Å) and thin (~ 10 Å) silicate films. In addition, we grew SiO@sub 2@/HfO@sub 2@/SiO@sub 2@ layered films for interface studies. All samples were grown by remote plasma enhanced chemical vapor deposition at a temperature of 300 °C using hafnium tert-butoxide and silane in a helium carrier gas. After growth, thin film silicate samples were heated by rapid thermal annealing at 500 °C for 30 s, while the thick film silicates and layered structures were annealed at temperatures between 500 and 900 °C. Si 2p and Hf 4f core levels were studied along with valence band spectra using photon energies of 70, 100, 130, 150 and 170 eV. Core-level binding energies exhibit a linear dependence with alloy composition in the thick silicate films, and are expected to provide some information about the interfacial structure and relaxation behavior of the layered oxide films. We have used several photoemission methods for obtaining the band offset parameter as a function of the Hf/Si composition including edge extrapolation and core-level shift data. The linear edge approximation yields a valence band offset of ~ 2.9 ± 0.1 eV for an ultrathin film of HfSiO4. This value agrees with estimates of 3.0 - 3.1 eV based on unpublished tunneling data. Valence band offsets for other compositions will be presented based on data from thick oxide films.