Intrinsic memristance mechanism of crystalline stoichiometric Ge2Sb2Te5

The bipolar memristive switching of stoichiometric crystalline Ge2Sb2Te5 (GST) thin film has been demonstrated. In contrast to the filamentary switching reported previously for a GST memristor, the intrinsic memristance is interpreted as arising from a trap-associated space-charge limited current mechanism, which is confirmed by the frequency-dependent resistance and capacitance. The contributions of charge trapping in grain defects and grain boundary defects are analyzed, and the latter ones may dominate the resistance variation. Unraveling the intrinsic memristance of GST will help us further understand the conduction mechanism of chalcogenides and promote the design of future nonvolatile memory and neuromorphic devices.