A method for forming a complementary metal oxide semiconductor (CMOS) device includes growing a SiGe layer on a Si semiconductor layer, and etching fins through the SiGe layer and the Si semiconductor layer down to a buried dielectric layer. Spacers are formed on sidewalls of the fins, and a dielectric material is formed on top of the buried dielectric layer between the fins. The SiGe layer is replaced with a dielectric cap for an n-type device to form a Si fin. The Si semiconductor layer is converted to a SiGe fin for a p-type device by oxidizing the SiGe layer to condense Ge. The dielectric material is recessed to below the spacers, and the dielectric cap and the spacers are removed to expose the Si fin and the SiGe fin.