A microfabricated transistor device includes a vertical stack of two or more channels of field effect transistors on a semiconductor substrate. Each of the channels has a vertical conductive path relative to a surface of the semiconductor substrate. At least one of the channels includes a shell formed around a core material, the shell including epitaxial material. The vertical stack can include a channel for a PMOS field effect transistor, and a channel for an NMOS field effect transistor.