Nano-synaptic response in graphene oxide by scanning probe microscopy

Two-dimensional (2D) layered materials have raised most interest and are attractive for the fabrication of high-density electronic devices, due to its atomically thin layer and extraordinary properties (e.g. high mechanical strength, high electrical and thermal conductivity). Vertical resistive memory is recognized as one of the most promising electronic synapses for neuromorphic computing, enabling fast and low-power information procession and storage. However, most memristive electronic neurons and synapses in the literature are very large (area >10⁴ µm²), resulting in low integration density and high-power consumption. In this talk, I will introduce a scalable spray-coating method to fabricate graphene oxide (GO), and the use of an enhanced conductive atomic force microscope (CAFM) setup to analyze nano-synaptic response in ultra-small areas (<50 nm²). I observed that metal/GO/metal nano-synapses exhibit potentiation and paired pulse facilitation at low current levels <1 µA, controllable excitatory post-synaptic currents, and long-term potentiation/depression. This work represents an important advancement to the nanoelectronic characterization of electro-synaptic behaviors in multiple materials, and this technique could generate useful knowledge in the field of high-density and energy-efficient artificial neural networks.