Methods for depositing oxide thin films, such as metal oxide, metal silicates, silicon oxycarbide (SiOC) and silicon oxycarbonitride (SiOCN) thin films, on a substrate in a reaction space are provided. The methods can include at least one plasma enhanced atomic layer deposition (PEALD) cycle including alternately and sequentially contacting the substrate with a first reactant that comprises oxygen and a component of the oxide, and a second reactant comprising reactive species that does not include oxygen species. In some embodiments the plasma power used to generate the reactive species can be selected from a range to achieve a desired step coverage or wet etch rate ratio (WERR) for films deposited on three dimensional features. In some embodiments oxide thin films are selectively deposited on a first surface of a substrate relative to a second surface, such as on a dielectric surface relative to a metal or metallic surface.