Migration of nitrogen in hexagonal Ge2Sb2Te5: An ab-initio study

Abstract

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 1.19 eV for the nitrogen atom suggest that it is difficult for it to move from one site to any other site or diffuse out from Ge2Sb2Te5 although doped nitrogen is energetically less stable with respect to N2 in vacuum. N2 in Ge2Sb2Te5 was hardly expected to dissociate into nitrogen atoms and vice versa. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)