Electrical conductivity measurements in Ge₂Sb₂Te ₅ films

Thin films of Ge₂Sb₂Te₅ were prepared using thermal evaporation technique. The amorphous structure and stoichiometery of the films were identified by X-ray diffraction and Energy Dispersive X-ray analysis, EDX. The conductivity measurements were carried out using DC I-V curves and AC Impedance spectroscopy techniques. The measured activation energy (E_v) is found to be about 0.36-0.39 eV, respectively, which is approximately half the energy gap (E_g= 0.72-0.78 eV). The amorphous-crystalline transition temperature (T_c) of the films was also estimated to be 135°C. The results can be reserved as an evidence for the chalcogenide nature defects in Ge₂Sb₂Te₅ films.