Physical properties' temperature dynamics of GeTe, Ge2Sb2Te5 and Ge2Sb2Se4Te1 phase change materials

The work presents the results of comprehensive studies of the electrical resistivity and optical transmission coefficient temperature dynamics, phase transition heats, the phase composition, and Raman spectra of GeTe, Ge2Sb2Te5 (GST225), and Ge2Sb2Se4Te1 (GSST(2241)) samples obtained by vacuum thermal deposition. The phase transition from the amorphous to the crystalline state with intense crystallization for GSST2241 at ?(alpha) = 595 K which was first determined in our work. It was shown that the stepwise change in the electrical resistivity for a thin-film GeTe was 4.5 orders of magnitude and for GST(225) - 5 orders and as for GSST(2241) this value reached 6 orders of magnitude, the change in the relative optical transmittance delta T/T reached almost 100%. The temperature regions with the maximum values of the derivatives of resistivity and optical transmittance are in good agreement with the temperatures of crystallization (phase transitions) determined by the DSC method.