Amorphization induced in crystalline GeSb₂Te₄ films by single femtosecond pulses

The dynamics and the conditions of amorphous transitions induced in a GeSb₂Te₄ system upon a single 108 fs pulse melting were studied by real-time optical microscope measurements. The system has a multilayer structure of 100 nm ZnS-SiO₂/35 nm GeSb₂Te₄/120 nm ZnS-SiO₂/0.6 mm polycarbonate substrate. The amorphization is completed within 2.6 ns. The thickness of the phase change layer plays an important role in controlling the heat flow conditions in the system upon a fs pulse irradiation. The relative thermal process and effects are analyzed. The mechanism of crystalline to amorphous transition triggered by single femtosecond laser pulse is discussed.