Investigation of the phase transition of Ge2Sb2Te5 films using internal friction method

Abstract The phase transition of Ge 2 Sb 2 Te 5 has been studied by internal friction measurement. Two Q − 1 peaks were observed during the process of heating amorphous Ge 2 Sb 2 Te 5 from room up to 400 °C. With a heating rate of 5.5 °C/min, the first peak (P1) is located at 180 °C and the second peak is (P2) located at 330 °C. Only the peak P1 appears when sample has been beforehand annealed at 230 °C for 1 hour. Both the peaks P1 and P2 don’t appear when sample has been beforehand annealed at 380 °C for 1 hour. The positions of P1 and P2 are both affected by the heating rate, and they follow Kissinger relation. The activation energy corresponding to the peak P1 is 1.94 ± 0.18 eV, and the activation energy corresponding to the peak P2 is 3.49 ± 0.24 eV. The isothermal annealing experiment revealed that Q − 1 monotonously decreases with time t in the process of phase change, and the internal friction Q − 1 versus time t can be represented as Q − 1 ( t ) = Q − 1 (∞) − [Q − 1 (∞) − Q − 1 (0)] exp (− t / τ ). The characteristic time τ is affected by temperature, and ln τ increase linearly with T − 1 .