ELECTROCHROMIC NICKEL-OXIDE THIN-FILMS DEPOSITED UNDER DIFFERENT SPUTTERING CONDITIONS

In this work, non stoichiometric nickel oxide (NiOx) thin films were d eposited by r.f. reactive sputtering of a metallic nickel target in an O-2-Ar atmosphere. A systematic variation of two deposition parameter s was done: the oxygen flux (phi) and the r.f. power (P). The electroc hemical characterization of the films was performed in aqueous electro lyte. The spectral transmittance measurements, as well as the X-ray di ffraction analysis were performed ex-situ, while monochromatic transmi ttance and stress measurements were performed in situ. Samples deposit ed at low oxygen flux (or high power) are transparent, in contrast to those deposited at high oxygen flux (or low power), which are dark bro wn. The films were cubic NiO, with preferred orientation in the (111) direction. Lattice parameters increase with increasing oxygen flux dur ing deposition, but decrease with increasing power. For all samples, t he ratio O/Ni was greater than 1, as determined by Rutherford back-sca ttering analysis. Also, an important hydrogen content was found in the films. The relationship between optical, electrochemical, mechanical, structural and morphological behaviour of the above mentioned films w ill be reported and discussed in this work.