Structural transformation of SbxSe100−x thin films for phase change nonvolatile memory applications

Abstract

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.