Interfacial layer formation in Gd2O3 films deposited directly on Si(001)

Gd2O3 films were deposited on Si(0 0 1) substrates using electron-beam evap oration from pressed-powder targets. Near the surface of the films the comp osition is stoichiometric, according to the results of X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering measurements. Thermal stab ility of the films was evaluated in a series of samples annealed in O-2 bet ween 500 and 780 degreesC. Transmission electron microscopy reveals a compl icated multilayer structure even in the as-deposited film. The thicknesses of the constituent layers change with annealing, and the reaction depends o n the annealing temperature. X-ray reflectivity was used to verify the laye r thicknesses and to determine their composition. An SiOy layer was identif ied, as well as an intermediate, mixed (SiO2)(x)(Gd2O3)(1-x) layer, The sil icon dioxide fraction (x) increases with annealing temperature, reaching th e 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 veri fy the bonding of the constituent species, The SiOy layer forms a good elec trical interface with the substrate, but reduces the dielectric constant of the film. (C) 2001 Elsevier Science B.V. All rights reserved.