Interfacial layer formation in Gd2O3 ®lms deposited directly on Si(0 0 1)

Gd2O3 ®lms were deposited on Si(0 0 1) substrates using electron-beam evaporation from pressed-powder targets. Near the surface of the ®lms the composition is stoichiometric, according to the results of X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering measurements. Thermal stability of the ®lms was evaluated in a series of samples annealed in O2 between 500 and 780 C. Transmission electron microscopy reveals a complicated multilayer structure even in the asdeposited ®lm. The thicknesses of the constituent layers change with annealing, and the reaction depends on the annealing temperature. X-ray re¯ectivity was used to verify the layer thicknesses and to determine their composition. An SiOy layer was identi®ed, as well as an intermediate, mixed (SiO2)x(Gd2O3)1ÿx layer. The silicon dioxide fraction (x) increases with annealing temperature, reaching the value of 33% in the most extreme case. XPS and Auger depth pro®ling were used to gain additional insight into the elemental composition and to verify the bonding of the constituent species. The SiOy layer forms a good electrical interface with the substrate, but reduces the dielectric constant of the ®lm. # 2001 Elsevier Science B.V. All rights reserved.