Artificial Synapses Based on Ferroelectric Schottky Barrier Field-Effect Transistors for Neuromorphic Applications

摘要

Artificial synapses based on ferroelectric Schottky barrier field-effect transistors (FE-SBFETs) are experimentally demonstrated. The FE-SBFETs employ single-crystalline NiSi_(2) contacts with an atomically flat interface to Si and Hf_(0.5)Zr_(0.5)O_(2) ferroelectric layers on silicon-on-insulator substrates. The ferroelectric polarization switching dynamics gradually modulate the NiSi_(2)/Si Schottky barriers and the potential of the channel, thus programming the device conductance with input voltage pulses. The short-term synaptic plasticity is characterized in terms of excitatory/inhibitory post-synaptic current (EPSC) and paired-pulse facilitation/depression. The EPSC amplitude shows a linear response to the amplitude of the pre-synaptic spike. Very low energy/spike consumption as small as ～2 fJ is achieved, demonstrating high energy efficiency. Long-term potentiation/depression results show very high endurance and very small cycle-to-cycle variations (～1%) after 10~(5) pulse measurements. Furthermore, spike-timing-dependent plasticity is also emulated using the gate voltage pulse as the pre-synaptic spike and the drain voltage pulse as the post-synaptic spikes. These findings indicate that FE-SBFET synapses have high potential for future neuromorphic computing applications.