Gate-all-around semiconductor device and method of fabricating the same

A semiconductor device comprising:

• a semiconductor substrate comprising a crystalline semiconductor material;
• at least one suspended nanostructure extending in a first direction and formed at least partially above and between a pair of adjacent STI regions, the at least one suspended nanostructure being electrically connected to and mechanically supported by a source region and a drain region formed at opposite ends of the at least one suspended nanostructure in the first direction, wherein the at least one suspended nanostructure comprises a crystalline semiconductor material that is different from the crystalline semiconductor material of the semiconductor substrate;
• a cavity formed vertically between the at least one suspended nanostructure and the semiconductor substrate and laterally between sidewalls of the STI regions facing each other;
• and
• a gate stack surrounding the suspended nanostructure, wherein the gate stack extends to cover a top surface and the sidewalls of the STI regions and an exposed surface of the semiconductor substrate in the cavity.