A method for making a semiconductor device may include forming, on a substrate, at least one stack of alternating first and second semiconductor layers. The first semiconductor layer may comprise a first semiconductor material and the second semiconductor layer may comprise a second semiconductor material. The first semiconductor material may be selectively etchable with respect to the second semiconductor material. The method may further include removing portions of the at least one stack and substrate to define exposed sidewalls thereof, forming respective spacers on the exposed sidewalls, etching recesses through the at least one stack and substrate to define a plurality of spaced apart pillars, selectively etching the first semiconductor material from the plurality of pillars leaving second semiconductor material structures supported at opposing ends by respective spacers, and forming at least one gate adjacent the second semiconductor material structures.