GRADED SUPERLATTICE STRUCTURE FOR GATE ALL AROUND DEVICES

Silicon germanium (SiGe)/silicon containing superlattice structure and methods for forming the same are provided. Various embodiments utilize SiGe layers in a SiGe/Si superlattice structure, which include varying concentrations of germanium throughout the layer to achieve reduced dislocations or a dislocation-free superlattice. For example, in some embodiments, for each SiGe layer there is a core SiGe film with a low Ge content and two thinner SiGe layers or cladding layers positioned on opposing sides of the core SiGe film with each of the SiGe cladding layers having a higher Ge content then the core SiGe film. Various embodiments provide for SiGe layers having a germanium depth profile enabling strained SiGe superlattice deposition on Si{110} substrates.