Thin film characteristics of HfO2-TiO2 mixed oxides and nanolaminates formed by atomic layer deposition were studied using transmission electron microscopy (TEM), atomic force microscopy, X-ray reflectometry, and metal oxide semiconductor capacitors. The role of HfO2 underlayer and the impact of the location of TiO2 in HfO2-TiO2 gate dielectrics were also investigated. Some differences in grain-size distribution were observed between mixed oxides and nanolaminates. In mixed oxide films, the grains became smaller and clustered together to form elongated structures as TiO2 is added. For nanolaminates, the grains became smaller than HfO2 but they did not form elongated structures. Cross-sectional TEM showed that as-deposited HfO2-TiO2 films were amorphous with a thinner interfacial layer than that of HfO2. After annealing, films became rougher, with an increase in interfacial layer thickness. A minimum of 20 cycles of HfO2 (similar to 10 A) was needed as an underlayer to obtain well-behaved electrical characteristics. Capacitance-voltage stressing performed on these films showed improved charge trapping behavior for mixed oxide and nanolaminate structures.