The characteristics of ultrathin ZrO2 films deposited using molecular oxygen and the zirconium precursor Zr(Oi-Pr)2(thd)2 [where Oi-Pr is isopropoxide and the is 2,2,6,6-tetramethyl-3,5-heptanedionate] were investigated. The organometallic was dissolved as a 0.15 M solution in octane and introduced into the deposition chamber using a liquid injection system. The deposition rate was insensitive to molecular oxygen flow but changed with liquid injection rate and was thermally activated in the range 390-550°C. No evidence of Zr-C and Zr-Si bonds were found in the X-ray photoelectron spectroscopy (XPS), spectra, and carbon concentrations, <0.1 atom %, the detection limit of the XPS depth profiling measurements, were obtained at the lowest deposition temperatures and deposition rates. High-resolution transmission electron microscopy showed the ZrO2 films to be polycrystalline as deposited, with an amorphous zirconium silicate interfacial layer. The effects of postdeposition annealing were also demonstrated. After proper annealing treatments, promising capacitance-voltage and current voltage characteristics were achieved. A film with an equivalent oxide thickness of 2.3 nm showed current reductions of approximately two orders of magnitude when compared to SiO2, but some improvements are required if these films are to be used as a gate-insulator beyond the 100 nm CMOS (complementary metal oxide semiconductor) technology node.