The physical and electrical properties of noncrystalline Al2O3, Ta2O5, and their alloys, (Ta2O5)(x)(Al2O3)(1-x) are investigated. Characterization by Auger electron spectroscopy and Fourier transformation infrared spectroscopy confirm these alloys are homogeneous with pseudobinary in character, and display increased thermal stability. Capacitance - voltage and current density-voltage data as a function of temperature demonstrate 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.