Remote plasma atomic layer deposition (ALD) of SrTiO3 films with different [Sr]/[Ti] ratios is reported, employing Star-Ti [(pentamethylcyclopentadienyl)trimethoxy-titanium, (CpMe5)Ti(OMe)(3)] and Hyper-Sr [bis(trisisopropylcyclopentadienyl)-strontium with 1,2-dimethoxyethane adduct, Sr((Pr3Cp)-Pr-i)(2)DME] precursors and O-2 plasma. The as-deposited films were amorphous, but crystallized after post-deposition anneal above 500 degrees C. For annealed SrTiO3 films with [Sr]/[Ti] = 1.3 and a thickness of 50 nm, a high dielectric constant k > 80 and low leakage current of similar to 10(-7) A/cm(2) at 1 V were obtained. It is demonstrated that changes in the composition and microstructure are apparent in the optical dielectric function of the SrTiO3 films, as obtained by spectroscopic ellipsometry. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3522768] All rights reserved.