The influence of Se doping upon the phase change characteristics of GeSb2Te4

Se substituted GeSb₂Te₄ films have been investigated for property contrast using electrical four-point-probe measurements, in-situ X-ray diffraction (XRD), a static tester probing the optical changes and atomic force microscopy (AFM). The temperature dependent sheet resistance measurements show two transitions at 125 and 262 °C. The first transition at 125 °C is accompanied by a large resistance change of three orders of magnitude. The resistance change for the second step is less pronounced. In-situ X-ray scattering experiments evidence that the first steep change in resistance is due to an amorphous → NaCl type structural transformation. The second change is caused by the transition from the cubic structure to the stable rhombohedral phase. Power–time effect (PTE) diagrams recorded to monitor the optical contrast of the films upon laser irradiation exhibit a fast recrystallization time of about 100 ns. The change of film roughness and topography between the amorphous and crystalline phase has been determined by AFM.