The ultrafast charge carrier dynamics of ZnO thin films and double layered BaTiO3/ZnO heterostructures were studied applying a combined approach of spectroscopic ellipsometry and femtosecond pump - supercontinuum probe experiments. Using both sub and above bandgap excitation (400 nm and 266 nm pump wavelength, respectively), a comprehensive dynamical picture could be obtained for ZnO. In particular, the mechanisms of exciton formation and recombination via different channels were identified. Also for BaTiO3 a detailed understanding of the dynamics after femtosecond above band-gap excitation was obtained. On this basis, ultrafast dynamical processes related to the interface in BaTiO3/ZnO heterostructures were recognized. In particular, transport across the interface of charge carriers photo-excited in ZnO was found. In addition, hints could be perceived that an induced polarization in BaTiO3 is influencing the carrier dynamics in the ZnO layer. The understanding of dynamics was complemented and further augmented by intensity dependent and thickness dependent studies.