Thin films of tantalum oxide have been deposited on Si(100) substrates using atomic layer deposition (ALD) employing the TaI5 and O 2 precursor combination. Growth was studied in the temperature region 400 to 700°C. The resulting films were found to be iodine-free above 450°C, and consisted of the polycrystalline orthorhombic ß-Ta 2O5 phase. The growth rate was found to be strongly dependent on the deposition temperature, reaching a maximum of 0.17 nm cycle-1 at 600°C.