Common signature of many-body thermal excitation in structural relaxation and crystallization of chalcogenide glasses

The structural stability of amorphous chalcogenides used in electrical and optical phase-change devices is critically affected by structural relaxation (SR) and crystallization. We studied the temperature activation of SR and crystallization in amorphous Ge2Sb2Te5. We demonstrate that SR and crystallization coherently obey the same Meyer–Neldel (MN) rule, evidencing the key role of many-body thermal excitation in these transformations. The different activation energies for SR and crystallization are discussed based on the strength and number of bonds to be rearranged during the transitions. The MN rule provides a straightforward explanation of the unphysical pre-exponential times (10−24–10−22 s) observed in chalcogenide glasses.