This article describes the structure and electrical properties of a high-k ytterbium titanium oxide (Yb2TiO5) gate dielectric deposited on Si(100) substrates through reactive cosputtering. X-ray diffraction, x-ray photoelectron spectroscopy, and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions (temperatures ranging from 600 to 800 degrees C). It is found that the Yb2TiO5 dielectrics annealed at 800 degrees C exhibited a thinner capacitance equivalent thickness of 1.65 nm, a lower gate leakage current of 38.4 nA/cm(2) at a gate voltage of -1 V, a smaller density of interface state of 9.61 x 10(10) 1/cm(2) eV, and a relatively lower hysteresis voltage of similar to 3 mV compared to those at other annealing temperatures. These results are attributed to the formation of a rather well-crystallized Yb2TiO5 structure, composition, and a smooth surface. This film also shows almost negligible charge trapping under high constant voltage stress. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3456126]