Characterization by Auger electron spectroscopy (AES) and Fourier transformation infrared spectroscopy (FTIR) confirms (Ta2O5),(Al2O3)(1-x) alloys are homogeneous pseudo-binary alloys with increased thermal stability with respect to end member oxides, Ta2O5 and Al2O3, Capacitance-voltage (C-V) and current density-voltage (J-V) data as a function of temperate show that the Ta d-states of the alloys act as localized electron traps, and are at an energy approximately equal to the conduction band offset of Ta2O5 with respect to Si. (C) 2002 Elsevier Science B.V. All rights reserved.