Simple square pulses for implementing spike-timing-dependent plasticity in phase-change memory

Phase-change memory (PCM) is a promising candidate as an artificial synapse. A compact operation method to implement synaptic functions with low power consumption is critical for constructing large-scale neuromorphic system. Here we propose a square spike strategy for implementing spike-timing-dependent plasticity (STDP) in PCM. Based on the heat accumulation effect in PCM, modulating the time intervals of pre- and post-spikes results in different heat generation and dissipation conditions, which lead to various crystalline/amorphous ratios in the phase change material layer in devices with diverse synaptic weights. Four forms of STDP learning rule are experimentally demonstrated. This study will further promote the development of PCM technology involved in neuromorphic systems. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim