Side-liquid-gated electrochemical transistors and their neuromorphic applications

A generic strategy to regulate various synaptic transistors is of great significance for the integration of multiple synaptic devices with multiple neuromorphic functionalities (e.g., olfactory, auditory, visual sensations, etc.) in an artificial neural network. Here, side-liquid-gated n-type In2O3, 2D MoS2, and p-type pentacene synaptic transistors based on a proton conducting mechanism and hysteresis engineering are proposed. The operating voltage can be significantly reduced from 30 to 3 V by using a high permittivity Er2O3 dielectric layer replacing traditional SiO2. Fundamental synaptic behaviors of both short-term plasticity (STP) and long-term plasticity (LTP) are successfully emulated on all three devices, providing the opportunity to integrate different semiconductor materials on one single chip to fabricate a multifunctional brain network. Interestingly, the PEO and PEO:LiClO4 side-gate electrolytes display different inhibitory post-synaptic currents (IPSCs) due to the difference in the proton-conducing activity and this generates distinct dynamic filtering response characteristics. Most importantly, a proof-of-principle artificial stereo vision system for 3D-object recognition is also constructed based on multiterminal In2O3/Er2O3 synaptic transistors. This novel side-gate regulating strategy is expected to accelerate the development of sophisticated neural networks and provide a great potential for neuromorphic applications.