Fig. 1: Structural transformation and data retention ability.

a Temperature dependence of the sheet resistance of ~300-nm-thick Ge₂Sb₂Te₅ and Sc_xSb₂Te₃ (x = 0.1, 0.2, and 0.3) films at the same heating rate of 10 °C min⁻¹. The crystallization temperature (T_c) is indicated by the arrow: ~138, ~170, ~199, and ~163 °C for the Sc_0.1Sb₂Te₃, Sc_0.2Sb₂Te₃, Sc_0.3Sb₂Te₃, and Ge₂Sb₂Te₅ films, respectively. b–d BF-TEM images of ~20-nm-thick Sc_xSb₂Te₃ films annealed at ~220 °C. The SAED pattern of each sample is shown in the corresponding inset. e Raw radially integrated diffraction curves of the electron diffraction intensity extracted from the respective SAED patterns shown in (b–d). f Ten-year data retention abilities for Ge₂Sb₂Te₅ and Sc_xSb₂Te₃ devices. The data were fitted using the Arrhenius equation t = Aexp(E_a/k_BT), where t is the time to failure when the cell resistance in the RESET state, at a certain isothermal heating temperature, falls to half of its initial magnitude, A is a proportionality constant, E_a is the activation energy, and k_B is the Boltzmann constant.