Detailed transmission electron microscopy characterization of HfO2 films deposited on Si(100) using atomic layer deposition has been carried out. The influence of deposition temperature has been investigated. At 226 degrees C, a predominantly quasi-amorphous film containing large grains of cubic HfO2 (a(0) = 5.08 angstrom) was formed. Grain morphology enabled the nucleation sites to be determined. Hot stage microscopy showed that both the cubic phase and the quasi-amorphous phase were very resistant to thermal modification up to 500 degrees C. These observations suggest that nucleation sites for the growth of the crystalline cubic phase form at the growing surface of the film, rather homogeneously within the film. The films grown at higher temperatures (300-750 degrees C) are crystalline and monoclinic. The principal effects of deposition temperature were on: grain size, which coarsens at the highest temperature; roughness with increases at the higher temperatures due to the prismatic faceting, and texture, with texturing being strongest at intermediate temperatures. Detailed interfacial characterization shows that interfacial layers of SiO2 form at low and high temperatures. However, at intermediate temperatures, interfaces devoid of SiO2 were formed. (c) 2006 Elsevier B.V. All rights reserved.