Fabrication and Characterization of Ferroelectric HfZrO-based Synaptic Transistors with Multi-state Plasticity

A ferroelectric HfZrO-based synaptic transistor with multi-state plasticity was demonstrated. The bottom-gated TiN/HfZrO/α-InGaZnO structure was utilized. In this device, accurate control of the polarization state in the ferroelectric HfZrO gate by the applied voltage could induce conductance modulation in channel, so that the multi-state plasticity of a neuron synapse could be mimicked. This device exhibited typical anticlockwise ferroelectric hysteresis window of 1 V, ~10
⁵
on/off current ratio, and 100 mV/dec subthreshold slope. An analog synaptic 20-state plasticity including potentiation and depression was observed with optimizable linearity and high dynamic ratio
$(> \mathbf{10}^{\mathbf{2}})$
at room temperature as the result of conductance modulation.