Impact of DoS changes on resistance drift and threshold switching in amorphous phase change materials

Role of activation energy in resistance drift of amorphous phase change materials

“…The absolute values of the drift exponent v determined in this work match quite well to literature data on memory cells in case of GST [16,17,31,34,[41][42][43][44] as well as on thin film samples for AIST and GeTe [17,44] as depicted in Table 1. The difference of the drift behavior between amorphous as-deposited samples compared to the melt-quenched cells seems to be sufficiently treated with the introduction of the virtual age t s .…”

“…Therefore, the thermal history of an amorphous as-deposited sample is complex and it is difficult to define a precise moment of amorphization as reference point for the time scale of a resistance drift measurement. Nevertheless, for measurements of amorphous as-deposited samples it has been shown, that the power law can be extended by a virtual age t s of the sample [17].…”

“…In the past the thin-film resistance was plotted vs. the time corrected by the virtual age, t + t s , while t s is handled as a free fit parameter [17]. This modification of raw data results in a straight line in a double logarithmic plot.…”

“…The common power law (blue dashed line) matches the experimental results well for long annealing times only. An extended power law (red dashed line) taking into account the thermal history of a sample, however, can describe the resistance drift in amorphous as-deposited phase change films over the whole measurement range [17].…”

“…Also, a change of thermopower with time has been measured on thin films of amorphous phase change materials [15]. And finally, the temperature dependence of the resistance in both thin films and phase change memory cells has been observed to change during drift [16,17].…”