In this review, an introduction to nanostructured films focusing on cerium oxide (CeO2) as high dielectric constant (k) material for silicon-based metal-oxide-semiconductor devices, and subsequently background of using low k silicon dioxide as well as the transition to high k materials was presented. Moreover, the properties of CeO2 in general and the applications of CeO2 and doped CeO2 films as high k passivation layers were reviewed. The beneficial effect of using CeO2 seed layers on the characteristics of CeO2 nanostructures was discussed. Moreover, challenges faced by CeO2 and the potential of doping trivalent cations into the CeO2 lattice for enhancement of passivation properties were thoroughly discussed.