Hardware electronic synapse and neuro-inspired computing system based on phase change random access memory (PCRAM) have attracted an extensive investigation. However, due to the intrinsic asymmetric reversible phase transition, the defective weight update of PCRAM synapses in aspects of tuning range, linearity and continuity has long required a system-level complexity of circuits and algorithms. The cell-level improvements to a great extent may slim the system thus achieving efficient computing. We report in this work the great enhancement of Ge₂Sb₂Te₅ (GST) based PCRAM synapses by combining materials engineering and pulse programming. It is found that carbon doping in GST retards the rate of phase changing thus increasing the controllability of the conductance, while non-linear programmable pulse excitations can eventually lead to a reliable synaptic potentiation and depression. A set of improved programmable pulse schemes for spike-timing dependent plasticity was then demonstrated, suggesting its potential superiority in flexible programming and reliable data collection. Our methods and results are of great significance for implementing PCRAM electronic synapses and high-performance neuro-inspired computing.

基于相变随机存取存储器（PCRAM）的硬件电子突触和受神经启发的计算系统引起了广泛的研究。然而，由于固有的不对称可逆相变，PCRAM 突触在调谐范围、线性和连续性方面的权重更新缺陷长期以来需要电路和算法的系统级复杂性。单元级别的改进在很大程度上可以使系统瘦身，从而实现高效计算。我们在这项工作中报告了 Ge ₂ Sb ₂ Te _{5的显着增强}(GST) 基于 PCRAM 的突触结合材料工程和脉冲编程。发现 GST 中的碳掺杂延缓了相变速率，从而增加了电导的可控性，而非线性可编程脉冲激发最终可以导致可靠的突触增强和抑制。然后展示了一组改进的用于尖峰定时依赖可塑性的可编程脉冲方案，表明其在灵活编程和可靠数据收集方面的潜在优势。我们的方法和结果对于实现 PCRAM 电子突触和高性能神经启发计算具有重要意义。