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

Abstract

The phase transition of Ge2Sb2Te5 has been studied by internal friction measurement. Two Q−1 peaks were observed during the process of heating amorphous Ge2Sb2Te5 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 1hour. Both the peaks P1 and P2 don’t appear when sample has been beforehand annealed at 380°C for 1hour. 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±0.18eV, and the activation energy corresponding to the peak P2 is 3.49±0.24eV. 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 lnτ increase linearly with T−1.