A semiconductor structure is provided that includes a fin stack structure of, from bottom to top, a first semiconductor material fin portion, an insulator fin portion and a second semiconductor material fin portion. The first semiconductor material fin portion can be used as a first device region in which a first conductivity-type device (e.g., n-FET or p-FET) can be formed, while the second semiconductor material fin portion can be used as a second device region in which a second conductivity-type device (e.g., n-FET or p-FET), which is opposite the first conductivity-type device, can be formed.