High-Performance Floating Gate Heterostructure With WSe2-MoS2 Diode Channel for Neural Synapse

In this letter, we propose a novel floating gate heterostructure based on two-dimensional (2D) materials, with WSe
₂
-MoS
₂
forming a p-n diode to serve as the channel and multilayer graphene as the floating gate. Different from previous floating gate devices, the p-n diode is used here instead of a single layer of 2D material in the channel layer to improve the gate-tuning capability. Our device exhibits a large memory window (14 V), high ON/OFF ratio (
$10^{{4}}$
), stable retention (5000 s), and cyclic endurance (1500 cycles). When used as a neural synapse, the device is able to realize a high max-min conductance ratio (
${G} _{\text {max}}/{G} _{\text {min}}$
= 28), low nonlinearity coefficients (
$\nu $
) of −2.0 for potentiation and −2.5 for depression, and record low energy consumption of 9 (15) aJ per spike in potentiation (depression). Our work provides a novel design of 2D-material heterostructure to be used as an implementation of neural synapses for neuromorphic computing.