Oxygen vacancy ordering in epitaxial layers of yttrium oxide on Si (001)

The origin of the superstructure observed in epitaxial yttrium oxide (Y2O3) layers on Si (001) is determined by electron energy loss spectroscopy (EELS). The oxygen K edge is measured both in the superstructure and a defect-free region of the Y2O3 layers and they are compared to EELS spectra obtained from bulk stoichiometric and reduced Y2O3. It is shown that as a result of the epitaxial growth, oxygen vacancies order into a superstructure creating nonstoichiometric regions in an otherwise stoichiometric Y2O3 layer. Furthermore, it is shown that oxygen deficiency introduces a change of the density of states of the lower conduction band of Y2O3. (C) 2003 American Institute of Physics.