A device is disclosed that includes a first transistor device of a first type and a second transistor device of a second type positioned vertically above the first transistor, wherein the first type and second type of transistors are opposite types. The device also includes a gate structure for the first transistor and the second transistor, wherein the gate structure comprises a first gate electrode for the first transistor and a second gate electrode for the second transistor and a gate stack spacer positioned vertically between the first gate electrode and the second gate electrode so as to electrically isolate the first gate electrode from the second gate electrode.