First-principles investigation of the WC/HfO2 interface properties

The thermodynamic and electronic properties of tungsten carbide surfaces and interfaces with monoclinic hafnia (WC/m-HfO2) are investigated through first-principles calculations. We show that oxidation of the WC surface and of the WC/m-HfO2 interface is energetically favorable. An oxygen monolayer on the W-terminated WC(0001) surface gives rise to a larger vacuum work function than that for the C-terminated WC(0001) surface, while the opposite result is obtained for the WC(0001) effective work function on hafnia: a carbon intermediate layer results in larger work function than an oxygen intermediate layer. This result is explained by the atomic structure of the intermediate layers neighboring the interface which differ if the interface is O or C rich. (C) 2006 American Institute of Physics.