At present, the halkogenide semiconductors based on the Ge-Sb-Te system materials are actively used due to their successful application in the optical phase change memory and the perspectives of the application in the electric phase change memory. The simultaneous study on the Seebeck coefficient and the electrical conductivity temperature dependencies for the GeSbTe thin films, deposited by thermal evaporation in vacuum, has been performed. The structure and composition of the deposited thin films have been established. The Seebeck coefficient measurements point to the p-type conductivity of the layers over the entire temperature range. It has been determined that with the temperature increase from the room temperature to 135 °C the Seebeck coefficient and the resistivity have decreased from 450 to 360 μ V/K and from 30.9 to 0.47 Ωcm, respectively. In the temperature range from 135 up to 145 °C the drastic decrease of the parameters to 35 μV/K and 0.0029 Ω-cm occurs, respectively, which is due to the crystallization process. The estimation of the activation energies for the Seebeck coefficient and the electrical conductivity indicates to a possible two-channel conduction model in the p-type amorphous GeSbTe thin films. The developed and manufactured software-hardware complex permits to simultaneously investigate the temperature dependencies of the Seebeck coefficient and electrical conductivity of the phase change memory materials thin films.
Alexey V. Babich
National Research University of Electronic Technology, Moscow, Russia
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