Heteroepitaxial praseodymium sesquioxide films on Si(1 1 1): A new model catalyst system for praseodymium oxide based catalysts

The structure, growth and stoichiometry of heteroepitaxial Pr2O3 films on Si(1 1 1) were characterized by a combined RHEED, XRD, XPS and UPS study in view of future applications as a surface science model catalyst system. RHEED and XRD confirm the growth of a (0 0 0 1) oriented hexagonal Pr2O3 phase on Si(1 1 1), matching the surface symmetry by aligning the 〈 1 0 1 ¯ 0 〉 oxide in-plane direction along the 〈 0 1 1 ¯ 〉 Si azimuth. After an initial nucleation stage RHEED growth oscillation studies point to a Frank-van der Merwe growth mode up to a thickness of approximately 12 nm. XPS and UPS prove that the initial growth of the Pr2O3 layer on Si up to ∼1 nm thickness is characterized by an interface reaction with Si. Nevertheless stoichiometric Pr2O3 films of high crystalline quality form on top of these Pr–silicate containing interlayers.