Properties of rare earth oxide films

Abstract

We investigated the properties of rare earth oxide films produced by the vacuum evaporation of rare earth metallic films and their oxidation in an oxygen atmosphere; we also studied the silicon-rare earth oxide interface. The rare earth oxide films were characterized by good insulating properties: an electrical resistivity of more than 10 12 Ω cm, a dielectric permittivity of 7–20, a dielectric dissipation factor of 0.01 or less and a breakdown field strength of (2–6) × 10 6 V cm −1. The behaviour of the effective surface charge density curve at flat-band voltages for scandium, yttrium and lanthanum to lutetium was found to be identical with that of the thermal neutron capture cross section for these elements. The presence of a deep level located some 0.3–0.38 eV below the conduction band edge was observed in fast surface state spectra of Si/Ln 2O 3 structures (Ln  Sc, Y, La, Gd, Er). On heating an Si/Y 2O 3/Al structure at 423 K for 20 min with a gate voltage of +5 V we observed a shift in the capacitance-voltage curve of approximately 2.5 V towards more negative voltages; for the same conditions but with a gate voltage of −5 V the shift was about 1 V in the opposite direction.