The structural and electrical resistance properties of excess-Sb Ge2Sb2+xTe5 (Sb-GST) films were investigated. As the Sb-doping concentration was increased, the face center cubic structure of Sb-GST films was no longer observed, at Sb concentrations exceeding 27%, the amorphous phase directly changed to hexagonal closed-packed structures. The crystallization temperature of the 27% Sb-GST film was 15 degrees C higher than that of the Ge2Sb2Te5 (GST) film. The activation energies of the Sb-GST films also were greater than those of the GST films. These results indicate an increase in the stability of the Sb-doped films in the amorphous state compared with GST films. (c) 2008 Elsevier B.V. All rights reserved.