Embodiments of the invention provide methods for depositing dielectric materials on substrates during vapor deposition processes, such as atomic layer deposition (ALD). In one example, a method includes sequentially exposing a substrate to a hafnium precursor and an oxidizing gas to deposit a hafnium oxide material thereon. In another example, a hafnium silicate material is deposited by sequentially exposing a substrate to the oxidizing gas and a process gas containing a hafnium precursor and a silicon precursor. The oxidizing gas usually contains water vapor formed by flowing a hydrogen source gas and an oxygen source gas through a water vapor generator. In another example, a method includes sequentially exposing a substrate to the oxidizing gas and at least one precursor to deposit hafnium oxide, zirconium oxide, lanthanum oxide, tantalum oxide, titanium oxide, aluminum oxide, silicon oxide, aluminates thereof, silicates thereof, derivatives thereof or combinations thereof.