We describe the structural properties and electrical characteristics of thin thulium oxide (Tm2O3) and thulium titanium oxide (Tm2Ti2O7) as gate dielectrics deposited on silicon substrates through reactive sputtering. The structural and morphological features of these films were explored by X-ray diffraction, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and atomic force microscopy, measurements. It is found that the Tm2Ti2O7 film annealed at 800 degrees C exhibited a thinner capacitance equivalent thickness of 19.8 angstrom, a lower interface trap density of 8.37 x 10(11) eV (1) cm (2), and a smaller hysteresis voltage of similar to 4 mV than the other conditions. We attribute this behavior to the Ti incorporated into the Tm2O3 film improving the interfacial layer and the surface roughness. This film also shows negligible degrees of charge trapping at high electric field stress. (C) 2009 Elsevier B. V. All rights reserved.