Assessment of self-induced Joule-heating effect in the I − V readout region of polycrystalline Ge2Sb2Te5 Phase-Change Memory

The physical mechanisms that regulate carrier transportin polycrystalline chalcogenides, such as Ge2Sb2Te5 (GST),are still debated. Recently, self-induced Joule-heating (SJH) effecthas been claimed to be the key factor in explaining the nonlinearityof the I–V characteristics of polycrystalline GST-basedphase-change memory (PCM). In this paper, we carefully investigatethe SJH occurring in the GST material by analyzing theI–V characteristics of PCM cells at low voltages, i.e., in thememory-cell readout region. To accomplish the study, we usead hoc fabricated PCM devices allowing an easier evaluationof SJH occurring in the chalcogenide layer. A novel procedureto test the SJH effect is also proposed. A comparison betweennumerical simulations and compact modeling is discussed as well.Our paper shows that the SJH effect is not sufficient to reproducethe experimental I–V nonlinearity, claiming for new experimentsand theoretical investigations. Therefore, this paper can be considereda step forward toward the comprehension of the transportproperties of polycrystalline GST, which is a key aspect for robustmodeling of PCM devices.