Emulating Biological Synapses With Solution-Processed Ca-CuI Transistors: A Route to Low-Voltage Neuromorphic Hardware

In this paper, a CaxCu1-xI1+xbased synaptic transistor was fabricated using chitosan as the gate dielectric by doping CuI with varying concentrations of CaI2. The device with x = 0.06 demonstrates superior electrical performance. The forward-sweep transfer characteristic curve exhibited an Ion/Ioffratio of 1.3 × 104, a subthreshold swing of 54.81 mV/dec, a field-effect mobility of 8.76 cm2V-1s-1, and a threshold voltage of 1.1 V. The reverse-sweep transfer characteristic curve exhibited an Ion/Ioffratio of 1.6×104, a subthreshold swing of 144 mV/dec, a threshold voltage of 0.6 V, and a mobility of 15.12 cm2V-1s-1. Owing to the electric double layer (EDL) effect enabled by the chitosan dielectric, the device operates at a low voltage of below 2 V. Furthermore, artificial synaptic behaviors were simulated through both single-pulse and multi-pulse measurements, exhibiting key neuromorphic functionalities such as excitatory postsynaptic current (EPSC), short-term plasticity (STP), and long-term plasticity (LTP). The solution-processed fabrication of low-voltage Ca0.06Cu0.94I1.06synaptic transistors presents a promising approach for neuromorphic computing applications, supporting the development of energy-efficient brain-inspired systems and low-power artificial intelligence platforms.