Optical properties of thin CVD-tungsten oxide films by spectroscopic ellipsometry

The physical composition and optical constants of CVD-tungsten oxide films deposited onto Si substrates by W(CO)(6) pyrolysis at 200, 300 and 400 degr ees C has been obtained by ellipsometric measurements made in the spectral range of 0.35-0.7 mu m. It has been found that films formed at temperatures lower than 400 degrees C are amorphous, while WO3 deposition at 400 degree s C yields a polycrystalline structure. A two-layer model describes the exp erimental data well. In all cases a considerably thick and rough surface la yer is observed, the composition of which differs from that of the bulk fil m. (C) 1999 Elsevier Science B.V. All rights reserved.