A dielectric film containing HfO.sub.2/ZrO.sub.2 nanolaminates and a method of fabricating such a dielectric film produce a reliable gate dielectric having an equivalent oxide thickness thinner than attainable using SiO.sub.2. A gate dielectric is formed by atomic layer deposition of HfO.sub.2 using a HfI.sub.4 precursor followed by the formation of ZrO.sub.2 on the HfO.sub.2 layer.