Investigation Of Chalcogenide Electronic Synapse Device Measuring Method

Increasing density based on bit size reduction is currently a main driving force for thedevelopment of data storage technologies，and all of the current available storagetechnologies may approach their physical limits due to miniaturization. Artificial cognitivememory driven by new function which can continue Moore’s Law might become futurestorage technology development trend.In the paper, by comparing with current data storage technologies, the majoradvantages of artificial cognitive memory are expatiated. As an important cognitive device,electronic synapse has been concerned about by global researchers in recent years. Theelectronic synapse, which can storage information while can mimic some synapsecognitive function, is the basic of cognitive computation. A brief review of mechanisms ofbiology synapse is presented, and followed by precondition of the electronic synapse.Synaptic weight plasticity, which means synaptic weight can increase or decreaseaccording to the spike signal, is the most fundamental and critical character of synapse. Tomimic synaptic weight plasticity, electronic synapse should change its resistance graduallydepend on the electrical signal applied on it. Base on two mechanism, namely phasechange and memristive resistance change can chalcogenide material perform resistancemodulation.(1) Controlling the proportion of crystallization can modulation the resistance.(2) Changing the direction of current that go through can increase or decrease theresistance.Electronic measurement according to the resistance change mechanism and synapticfunction is design and carried out, four steps are included in the measurement, which areDC sweep, simple pulse measurement, pre and post-synaptic spike design and electronicsynapse function implement. Measurement platform is reconstructed to supply twochannels signal and collect feed-back signal. Two kinds of electronic synapse, which isbased on GeSbTe and AgInSbTe are measured and proved to achieve synapse function, namely spike-time-depend plasticity (STDP).