Double-Gate MoS₂Field-Effect Transistor with a Multilayer Graphene Floating Gate: A Versatile Device for Logic, Memory, and Synaptic Applications

Abstract

2D materials with low-temperature processing hold promise for electronic devices that augment conventional silicon technology. To meet this promise, devices should have capabilities not easily achieved with silicon technology, including planar fullydepleted silicon-on-insulator with substrate body-bias, or vertical finFETs with no body-bias capability. In this work, we fabricate and characterize a device [a double-gate MoS 2 field-effect transistor (FET) with hexagonal boron nitride (h-BN) gate dielectrics and a multi-layer graphene floating gate (FG)] in multiple operating conditions to demonstrate logic, memory, and synaptic applications; a range of h-BN thicknesses is investigated for charge retention in the FG. In particular, we demonstrate this device as a (i) logic FET with adjustable V T by charges stored in the FG, (ii) digital flash memory with lower pass-through voltage to enable improved reliability, and (iii) synaptic device with decoupling of tunneling and gate dielectrics to achieve a symmetric program/erase conductance change. Overall, this versatile device, compatible to back-end-of-line integration, could readily augment silicon technology.

Two-dimensional materials for artificial synapses: toward a practical application

“…Figures 2(b) and (c) illustrate the general structures of transistor-based synapses, where 2DMs may play roles in certain layers of transistor-based synapses. For instance, table 2 summarizes several reported transistor-based 2DM synapses, which are further categorized into the charge-storage transistor [89][90][91][92][93][94][95], electrolyte-gated transistor [96][97][98][99], ferroelectric-gated transistor [49,[100][101][102][103], and memtransistor [104,105] according to different operating mechanisms. The 2DMs with superior carrier mobility are most often adopted as the channel layer.…”

Recent Progress on Emerging Transistor‐Based Neuromorphic Devices

“…The relaxation of the ion in the gate electrolyte [167] Copyright 2020, IOP Publishing. [191] -S i À7.5 V/ þ10 V 3 ms -Synaptic weight modulation [174] enables the ion-gate transistor to simulate the dynamic characteristics of the biological neural systems, which enables the ion-gate synaptic transistors to emulate the short-term synaptic plasticity effectively. Due to strong lateral coupling effect, multi-gate structures enable the ion-gate neuromorphic transistors to achieve the dendritic integrations of neurons.…”

High-Performance Non-Volatile InGaZnO Based Flash Memory Device Embedded with a Monolayer Au Nanoparticles

“…Previously, non-volatile memory (NVM) devices based on thin-film transistors (TFTs) gained great potential because of minimum power dissipation to retrain the stored data and their conformal compatibility with complementary integrated circuits and electronic chips [ 1 , 2 , 3 , 4 , 5 , 6 ]. For typical NVM devices, the programming/erasing properties depend on the applied voltage to the control gate electrode (V program /V erase ) that leads to validate the memory window with the corresponding variation in the current level of a device as ‘on’ state and ‘off’ state, describing programmable and erasable constitutes of memories [ 7 , 8 , 9 ].…”

“…For typical NVM devices, the programming/erasing properties depend on the applied voltage to the control gate electrode (V program /V erase ) that leads to validate the memory window with the corresponding variation in the current level of a device as ‘on’ state and ‘off’ state, describing programmable and erasable constitutes of memories [ 7 , 8 , 9 ]. In this regard, floating gate NVM devices based on various semiconductors, such as two-dimensional (2D) materials (molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 )), [ 3 , 8 , 10 , 11 , 12 , 13 ] oxide materials (indium gallium zinc oxide (IGZO) and zinc oxide (ZnO)) [ 9 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] and organic materials (pentacene, poly(3-hexylthiophene) (P3HT), and dinaphthothienothiophene (DNTT)) [ 21 , 22 , 23 , 24 , 25 , 26 ] have recently been studied, exhibiting high-performance memory operations with greater endurance and retention properties but are still limited at obtaining reliable reproducibility, larger memory window with on-off ratio, low-temperature processing, and easy fabrication methods.…”