The migration barrier energies of the nitrogen atom and N2 molecule, and the activation barriers for the dissociation and formation of N2 in Ge2Sb2Te5 were calculated by ab initio methods. Various transition and metastable states were found along the migration pathway. Migration barrier energies up to 1.19eV for the nitrogen atom suggested that it was difficult for it to move from one site to any other site or diffuse out from Ge2Sb2Te5 although doped nitrogen was energetically less stable with respect to N2 in vacuum. N2 in Ge2Sb2Te5 was hardly expected to dissociate into nitrogen atoms and vice versa.

Migration of Nitrogen in Hexagonal Ge2Sb2Te5: an ab initio Study. S.J.Kim, J.Lee, S.C.Lee, C.Park, C.S.Hwang, J.H.Choi: Physica Status Solidi - Rapid Research Letters, 2012, 6[3], 108-10