Investigation of phase transition of Ge2 Sb2 Te5 and N-incorporated Ge2 Sb2 Te5 films using x-ray absorption spectroscopy

For this study, the phase-change materials Ge2 Sb2 Te5 and N-doped Ge2 Sb2 Te5 films were investigated using x-ray absorption near-edge structure and extended x-ray absorption fine structure. During the phase transition, change in electronic structure is observed by the shift of the absorption edge energy, i.e., structural coordination of Ge-Te changes from tetrahedral to octahedral coordination, of which the interatomic distances are 3.12 and 2.83 Å, respectively. In addition, nitrogen incorporation into the film led to a p-p orbital hybridization and a different crystallization behavior. The hybridization caused by the formation of a Ge-N bond was related to suppression of the phase transition.