Sub-3V, MHz-Class Electrolyte-Gated Transistors and Inverters

Electrolyte-gated transistors (EGTs) have emerging applications in physiological recording, neuromorphic computing, sensing, and flexible printed electronics. A challenge for these devices is their slow switching speed, which has several causes. Here we report the fabrication and characterization of n-type ZnO-based EGTs with signal propagation delays as short as 70 ns. Propagation delays are assessed in dynamically operating inverters and five stage ring oscillators as a function of channel dimensions and supply voltages up to 3V. Substantial decreases in switching time are realized by minimizing parasitic resistances and capacitances that are associated with the electrolyte in these devices. Stable switching at 1-10 MHz is achieved in individual inverter stages with 10-40 m channel lengths, and analysis suggests that further improvements are possible.