NiO films were grown on Si(100) by atomic layer deposition using Ni(Cp)(2) (Cp=cyclopentadienyl, C5H5) or Ni(EtCp)(2) [EtCp=ethylcyclopentadienyl, (C2H5)C5H4)] and ozone in the 150-300 degrees C temperature range. The growth temperature dependence of structure, electronic density, and impurity levels for the prepared NiO films was studied using X-ray reflectivity, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, time of flight-secondary ion mass spectroscopy (ToF-SIMS), and transmission electron microscopy. The behavior of films deposited using Ni(Cp)(2) and Ni(EtCp)(2) is compared and discussed. NiO films with good stoichiometry and low amounts of contaminants are obtained at a growth temperature (T-g) of 250 degrees C or above. At a fixed T-g, the growth rate for NiO films deposited using Ni(Cp)(2) is higher than the one of films deposited using Ni(EtCp)(2). Furthermore, the growth rate for NiO deposited using Ni(Cp)(2) at T-g = 150 degrees C is 0.32 nm/cycle and decreases substantially in films deposited at higher temperatures. The electronic density of NiO films deposited at 300 degrees C is close to the one of bulk NiO (1.83 e(-)/A(3)). According to XRD and FTIR results, films deposited at T-g >= 200 degrees C have a simple cubic polycrystalline structure. Impurities in NiO films decrease with increasing T-g, as detected by ToF-SIMS.