Phosphorene nano-heterostructure based memristors with broadband response synaptic plasticity

Motivated by the biological neuromorphic system with a high degree of connectivity to process huge amounts of information, light-triggered electronic synapses are expected to pave the way for overcoming the von Neumann bottleneck for non-conventional computing. Here, a light-triggered electronic synapse based on solution-processed ZnO-phosphorene nanoparticles (ZP NPs) with an in situ fabricated heterojunction is demonstrated. In situ Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (CAFM) have been employed to investigate the operation principle of the memristor. The essential synaptic functions of learning and memory of the bio-synapse have been emulated, including potentiation and depression under positive and negative pulse trains, paired-pulse facilitation (PPF), spike-rate-dependent plasticity (SRDP), spike-timing-dependent plasticity (STDP) and short-term potentiation (STP) to long-term potentiation transition (LTP). The well-arranged pn junction inside the ZP NPs arouses the multiple wavelength response and fast separation of photogenerated excitons, which serves as the basis for broadband optically-mediated plasticity. The experimental results confirm that ZP nanoparticles could be promising key components for mimicking biological synaptic behaviors with light stimulation, which is of great importance for the further development of artificial light triggered neural systems. A memristor and artificial synapse based on a ZnO-phosphorene nano-heterojunction are demonstrated. The continuous internal resistance states and multi-wavelength response of the memristor are applied to emulate the functions of the artificial synapse including PPF, SRDP, STDP and STP to LTP transition.