The disclosed technology generally relates to semiconductor devices and more particularly to a gate-all-around semiconductor device, and methods of fabricating the same. In one aspect, the method comprises providing on a semiconductor substrate between STI regions at least one suspended nanostructure anchored by a source region and a drain region. The suspended nanostructure is formed of a crystalline semiconductor material that is different from a crystalline semiconductor material of the semiconductor substrate. A gate stack surrounds the at least one suspended nanostructure.