Laser-induced metastable phase in crystalline phase-change films by confocal Raman spectrometer.

Understanding crystallization process in phase-change materials is very important for data storage application. Especially, accurately controlling the metastable phase transition as well as characterizing its structure evolution is still under investigation. In this study, phase transformations have occurs from amorphous to crystalline phases when the phase-change films were irradiated continuously by the 785 nm laser irradiation. By adjusting the laser power, the different metastable phases in conventional Ge2Sb2Te5, Sb2Te3, ZnSb, ZnSb-Al2O3 and ZnSb-ZnO were obtained and distinguished by their different Raman vibration modes. The effect of laser power on the phase-change threshold of these films was studied systematically. Large structural differences induced by laser irradiation were revealed based on the changes in Raman profiles. Our study may offer a new insight into an accurate control of distinct metastable state to realize optical multilevel memory.