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Fluorine-doped zinc oxide thin films, ZnO : F, were deposited by the chemical spray pyrolysis technique using zinc acetylacetonate, Zn(C 5 H 7 O 2 ) 2 , and ammonium fluoride as precursors. The molar concentration in the starting solution and the substrate temperature, T s , were varied in order to obtain transparent and conductive films. For molarities higher than 0.3 M, growth rate values on the order of 3.5 nm/s were obtained. As the molarity increases, the resistivity r decreases up to a minimum value in the order of 10 À2 W cm for films deposited from a 0.4 M starting solution and T s ¼ 475 C; for higher molarities an increase in r is observed. The preferential growth direction is affected by the molarity and T s , showing a switching of the (101) planes obtained for the lowest molarities (0.1 and 0.2 M) and T s < 475 C to the (002) preferential growth for molarities higher than 0.1 M and all the substrate temperatures used. The mobility and the carrier concentration were varied from 1 to 3 cm 2 /Vs and 4 Â 10 20 to 5 Â 10 20 cm À3 , respectively. From scanning electron micrographs, small grain size is evidenced, which can give rise to a high density of trapping states in the grain boundaries. Films were uniform, pinholes-free, with a transmittance in the visible in the order of 85%.

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