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The structural transformation and transformation kinetics of SbxSe100−x films (60⩽x⩽70) were studied to investigate the feasibility of applying SbxSe100−x alloys in phase change nonvolatile memories. Temperature-dependent van der Pauw measurements, x-ray diffraction, x-ray reflectometry, and a static tester were used to determine the structure and transformation kinetics of the SbxSe100−x films. The sheet resistance difference between the amorphous and crystalline states was higher than 104Ω∕◻. The crystalline structure of the metastable phase of SbxSe100−x alloys, which plays a major role in fast crystallization, is similar to that of Sb2Te (rhombohedral structure). The transition temperature, sheet resistance, and activation energy for transformation decrease as the amount of Sb increases in the SbxSe100−x film. The density and thickness variation of the Sb65Se35 thin film were 5.9% and 5.4%, respectively. Applying the Kissinger method, the activation energies for crystallization were in the range from 1.90±0.15to4.16±0.28eV. The desired crystallization speed can be obtained by a systematic change of the composition owing to the variation of the activation barrier with stoichiometry.

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The influence of doping upon the phase change characteristics of Ge 2 Sb 2 Te 5 (GST) has been determined with a variety of techniques including four-point-probe electrical resistance measurements, grazing incidence Xray diffraction (XRD), X-ray reflectometry (XRR) and a variable incident angle spectroscopic ellipsometer (VASE) and a static tester. Doping with Bi, Sn or In maintains the NaCl-type crystalline structure of GST but expands the lattice due to the larger atomic radii. Sufficient optical contrast is exhibited and can be presumably correlated with the pronounced density change upon crystallization. In the Bi and Sn doped case transition temperatures are reduced with regard to the undoped case. Ultra-fast crystallization within 10 ns is demonstrated, which is correlated with a single NaClstructure phase and a lower transition temperature arising from the weaker bonds. In the In doped case, however, crystallization is retarded, which can be correlated with the observed phase separation and the increased transition temperature.