Investigation of phase change in Ge2Sb2Te5 films by coherent phonon spectroscopy

Thermally induced phase transitions of Ge2Sb2Te5 are studied by coherent phonon spectroscopy. Changes of the coherent phonon spectra related to the crystallization of the sputter-deposited amorphous film and a further modification of the crystallographic structure are observed. The phonon modes detected can be assigned by a comparison with coherent phonon spectra of the binary Sb2Te3 and GeTe constituents.