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. Hk, 81.15.Fg, 82.80.Pv MoO 3 thin films were fabricated in this work by the laser evaporation method operating in continuous wave mode. The samples were prepared at different substrate temperatures, in vacuum and at different oxygen pressures. Oxidation states of the films were obtained by X-ray photoelectron spectroscopy (XPS) and the crystalline structure was studied with X-ray diffraction (XRD). Morphological studies of the samples also were carried out using SEM. XPS measurements showed the presence of 3p bonds corresponding to the MoO 3 . Additionally some peaks associated to Mo-O and O-H bonds appear in the XPS-spectra. The samples prepared under 473 K substrate temperature presented XRD spectra proper of amorphous samples; above this temperature the samples shown polycrystalline phases mixed with α and β phases. A high homogeneity on the films surface can be seen in SEM images.

The laser ablation of stationary KNbOs single crystal targets induces a Nb enrichment of the target surface. In rotated targets this effect is observed only in those areas irradiated with low laser fluence. The composition of the plasma formed close to the target surface is congruent with the target composition; however, at further distances K-deficient films are formed due to the preferential backscattering of K in the plasma. This loss may be compensated for by using K-rich ceramic targets. Best results so far have been obtained with [K]/[Nb] = 2.85 target composition, and crystalline KNbOa films are formed when heating the substrates to 650 "C. Films formed on (100)MgO single crystals are usually single phase and oriented with the (1 IO) film plane parallel to the (100) substrate surface. (100)NbO may coexist with KNbOa on (100)MgO. At substrate temperatures higher than 650 "C, niobium diffuses into MgO forming Mg4Nb209 and NbO, leading to K evaporation from the film. Films formed on (001) a-A&O3 (sapphire) show the coexistence of (11 l), (1 lo), and (001) orientations of KNbOs, and the presence of Nb02 is also observed. KNbOs films deposited on (001)LiNbOs crystallize with the (111) plane of the film parallel to the substrate surface. For the latter two substrates the Nb diffusion into the substrate is lower than in MgO and consequently the K concentration retained in the film is comparatively larger.

. Qp, 68.55.Jk, 73.25.+i, 73.61.Ng, 81.15.Fg In the present paper the growth of MoO3 thin films on common glass substrates are described. The films were prepared by evaporation of a MoO3 target with a CO2 laser (10.6 µm), operating in the continuous wave mode. The effect of substrate temperature on the crystallographic structure and electrical properties of MoO3 thin films was studied. The chemical composition of the different species formed on the films surface was obtained by X-ray photoelectron spectroscopy (XPS) and the crystalline structure was studied with X-ray diffraction (XRD). The electrical conductivity of the films was determined using the standard four-points method. Conductivity of the films varied from de 10 −9 to 10 −5 (Ωcm) −1 in the 300-600 K temperature range. Arrhenius-type plots for the electrical conductivity indicate the presence of at least two different conduction mechanisms. The I-V characteristic curve shows an ohmic behavior only in the 4.5-60 V range. Outside this interval the I-V curve has a behavior described by a power law.

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