Investigation of the Crystallization Kinetics in Ge-Sb-Te-Bi Thin Films for Phase Change Memory Application

A.V. Babicha, A.A. Sherchenkova, S.A. Kozyukhinb and S.P. Timoshenkova aNational Research University of Electronic Technology, Building 1, Shokin square, Zelenograd, Moscow, Russian Federation bKurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31 Leninsky prospect, Moscow, Russian Federation

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In this work the mechanism and kinetics of crystallization of the Ge2Sb2Te5+Bi thin films were investigated using differential scanning calorimetry. Ge2Sb2Te5 with different amounts of Bi (0, 0.2, 0.5, 0.8, 1, 3, 5 wt.%) was synthesized using quenching technique. Thin films were prepared by thermal evaporation of synthesized materials. X-ray diffraction has shown that synthesized materials had trigonal modification of Ge2Sb2Te5. Introduction of Bi led to the appearance of trigonal modification of Bi2Ge2Te5, which indicates on the replacement of Sb by Bi. As-deposited thin films were amorphous up to 3% of Bi. Higher concentrations of Bi led to the appearance of crystalline phases. Composition of thin films was verified by Rutherford backscattering, and was found to be close to that of the synthesized materials. The joint application of model-free Ozawa-Flynn-Wall and model-fitting Coates-Redfern methods allowed to estimate kinetic triplet for crystallization process of GST225+Bi thin films, and to predict data processing and storage times of the phase change memory cells. It was shown that GST225+0.5 wt.% Bi thin films have the most promising kinetic characteristics among the investigated materials, due to the predicted smallest data processing and largest storage times.

DOI: 10.12693/APhysPolA.129.717 PACS numbers: 65.60.+a