Phase-change Ge8Sb92 films were deposited on the varied thermal-conductivity substrates by radio frequency sputtering and their crystallization behavior was investigated. Situ sheet resistance measurement and the X-ray diffraction spectra show a double stage phase transitions of Ge8Sb92 films on the low thermal-conductivity substrates while a single stage phase transition on the high ones with the increasing heating temperature. The first-stage phase transition is amorphous-to-crystalline transition and the second-stage phase transition is partial-to-complete crystalline transition. The results provide experimental basis for the optimization of Ge8Sb92 phase-change memory and the possibility application in three-level electrical storage with single layer GeSb-type phase-change materials.
