Structure of copper-doped tungsten oxide films for solid-state memory

Copper-doped WO3 films, which are an active media for programmable metallization cell memory devices, are studied. The highlights of this study are the intercalation products forming on the interface between the WO3 and Cu during thermal evaporation and also after thermal or photothermal diffusion of Cu into WO3 films. The diffusion profile is established using Auger spectroscopy. Further characterization is provided using Raman spectroscopy which gives evidence for formation of products with a lower valence state related to W and oxidation products related to Cu. The composition of the intercalation products containing Cu is confirmed using X-ray diffraction which shows the formation of copper oxides and tungstates. (c) 2007 Elsevier B.V. All rights reserved.