An apparatus for depositing film stacks in-situ (i.e., without a vacuum break or air exposure) are described. In one example, a plasma-enhanced chemical vapor deposition apparatus configured to deposit a plurality of film layers on a substrate without exposing the substrate to a vacuum break between film deposition phases, is provided. The apparatus includes a process chamber, a plasma source and a controller configured to control the plasma source to generate reactant radicals using a particular reactant gas mixture during the particular deposition phase, and sustain the plasma during a transition from the particular reactant gas mixture supplied during the particular deposition phase to a different reactant gas mixture supplied during a different deposition phase.