The synergistic effects of NH3 ambient and ultraviolet illumination on the dielectric properties of hafnia based gate dielectrics are reported in this paper. The films were processed at relatively low temperatures (similar to 400 degrees C) by pulsed laser ablation and UV oxidation technique. UV illumination and the NH3 ambient created a thin and a denser interfacial layer (at the film-Si interface) comprised of Hf-Si-O-N bonding. As a result of the interfacial layer modification, a leakage current density lower than 10(-4) A/cm(2) and a dielectric constant of similar to 21.7 were extracted from the best samples processed in NH3 and under UV illumination. The nitrogen doped HfO2 also exhibited a thinner interfacial layer (similar to 12 angstrom) in comparison to the films processed without NH3 ambient. (C) 2007 Elsevier B.V. All rights reserved.