Synaptic Behaviors in Ferroelectric-Like Field-Effect Transistors with Ultrathin Amorphous HfO2 Film

We demonstrate a non-volatile field-effect transistor (NVFET) with a 3-nm amorphous HfO2 dielectric that can simulate the synaptic functions under the difference and repetition of gate voltage (VG) pulses. Under 100 ns write/erase (W/E) pulse, a memory window greater than 0.56 V and cycling endurance above 106 are obtained. The storied information as short-term plasticity (STP) in the device has a spiking post-synaptic drain current (ID) that is a response to the VG input pulse and spontaneous decay of ID. A refractory period after the stimuli is observed, during which the ID hardly varies with the VG well-emulating the bio-synapse behavior. Short-term memory to long-term memory transition, paired-pulse facilitation, and post-tetanic potentiation are realized by adjusting the VG pulse waveform and number. The experimental results indicate that the amorphous HfO2 NVFET is a potential candidate for artificial bio-synapse applications.