Interfacial layer formation in Gd 2O 3 films deposited directly on Si(0 0 1)

Abstract

Gd 2O 3 films were deposited on Si(0 0 1) substrates using electron-beam evaporation from pressed-powder targets. Near the surface of the films the composition is stoichiometric, according to the results of X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering measurements. Thermal stability of the films was evaluated in a series of samples annealed in O 2 between 500 and 780°C. Transmission electron microscopy reveals a complicated multilayer structure even in the as-deposited film. The thicknesses of the constituent layers change with annealing, and the reaction depends on the annealing temperature. X-ray reflectivity was used to verify the layer thicknesses and to determine their composition. An SiO y layer was identified, as well as an intermediate, mixed (SiO 2) x (Gd 2O 3) 1− x layer. The silicon dioxide fraction ( x) increases with annealing temperature, reaching the value of 33% in the most extreme case. XPS and Auger depth profiling were used to gain additional insight into the elemental composition and to verify the bonding of the constituent species. The SiO y layer forms a good electrical interface with the substrate, but reduces the dielectric constant of the film.