Formation of GaSb core-shell nanofibers by a thermally induced phase decomposition process

Dense networks of amorphous GaSb nanofibers were fabricated by ion irradiation of bulk GaSb, and following formation, they were thermally annealed at a low temperature. Contrary to expectations, annealing of the GaSb fibers at just 50% of their melting temperature resulted in complete chemical decomposition of the nanofibers into core-shell structures consisting of crystalline Sb cores surrounded by amorphous shells. In this study, we investigate the transition of the single-phase nanofibers to their core-shell configuration, and we analyze the unique, temperature-dependent phase decomposition process. Thermodynamic considerations are discussed, and a model is presented to explain the thermally induced decomposition of the GaSb semiconductor fibers into core-shell structures, based upon the singular interaction of several size-dependent material properties.