Electroforming-free nonvolatile resistive switching of redox-exfoliated MoS₂ nanoflakes loaded polystyrene thin film with synaptic functionality

Abstract

Here, we report robust and highly reproducible nonvolatile resistive switching (RS) devices with artificial synaptic functionalities utilizing redox-exfoliated few-layered 2H-MoS 2 nanoflakes. Advantageous polar solvent compatibility of 2D MoS 2 from this method were utilized to fabricate thin film devices very easily and cost-effectively using polystyrene as matrix. Prominent RS property of polystyrene thin film devices with varying MoS 2 concentrations strongly favors electroforming-free operation. The conduction band position of 2D MoS 2 nanosheet in combination with the work functions of chosen electrodes looks alleviating to switch the current from low to high at a suitable positive bias voltage. We further confirmed the mechanism of charge transport through fitting the results with theoretical models, say injectiondominated Schottky emission model for low-conducting states and space-charge-limited current mechanism for the high-conducting state. Interestingly, a relatively high current On/Off ratio 10 2 was recorded during the pump-probe testing to show resistive random-access memory (ReRAM) application. Finally, artificial synaptic functionalities-the building blocks of neuromorphic computing architectures is also illustrated by considering the robust RS property and ReRAM application.

Solution-Processed Robust Multifunctional Memristor of 2D Layered Material Thin Film

“…Interestingly, the photoluminescence (PL) spectrum shows a strong A-exciton peak centered at 1.76 eV with an weak peak (I) at an energy of about 1.4 eV (883 nm) for the indirect band gap transitions as shown in Figure S1b in the Supporting Information, which confirms our MoS 2 sample is mostly direct band gap in nature. , Figure b shows a Raman scattering spectrum of a MoS 2 thin film deposited over a glass substrate using a biphasic method consisting of two prominent scattering peaks for in-plane E 2 g 1 and out-of-plane A 1g vibrational modes at 380.3 and 405.4 cm –1 , respectively, with a wavenumber gap (Δ) of 25.1 cm –1 . Hence, this Raman scattering result precisely confirms the presence of few-layer-thick 2D MoS 2 nanosheets in the thin film, which are semiconducting in nature with a 2H crystalline phase …”

“…In the SCLC mechanism, the injected carriers from the electrode take the lead over the thermally generated carriers and also need an Ohmic contact. In our ITO/2D MoS 2 /EGaIn device, the conduction band minimum (4.28 eV) of MoS 2 perfectly formed an Ohmic contact with the EGaIn (4.2 eV) and operated as an electron-only device, which mostly follows the Mott–Gurney law (see eq ) , I = 9 8 ε μ A d 3 V 2 where I , μ, ε, A , and d represent the current, electron mobility, permittivity of 2D MoS 2 , device area, and MoS 2 layer thickness, respectively. Equation can be generalized further to a power law relation of I ∝ V α , where α is a constant and a value higher than unity represents the SCLC conduction mechanism.…”

“…Recently, atomically thick 2D layered van der Waals (vdW) materials have attracted significant interest due to their attractive mechanical, chemical, electronic, and optoelectronic properties. They show promising results for various applications, including thin film transistors, photodetectors, catalysis, sensing, data storage, and neuromorphic computing. ,− Among the entire 2D materials library, MoS 2 is a champion material due to its various functionalities. ,, Hence, the growth of a high-quality MoS 2 thin film is critical to display high performance for sophisticated applications. Accordingly, chemical vapor deposition (CVD) and liquid-phase exfoliation (LPE) are the most common processing techniques to prepare atomically thick 2D MoS 2 sample .…”

Enhanced Synaptic Characteristics under Applied Magnetic Field in V2O5/NiMnIn-Based Switching Device for Neuromorphic Computing

“…The Internet of Things and machine learning generate massive electronic data workloads in the rapidly growing field of information technology. − Developing highly efficient, large data storage capacity and fast memory devices in a compact size can resolve the aforementioned issues. The performance and durability of memory devices are frequently compromised by heating effects resulting from downscaling the transistor size. − Moreover, conventional circuits fail with a reduced transistor size below 2–3 nm beyond the quantum tunneling phenomenon. − The increased data size leads to challenges for traditional computers based on von Neumann’s architecture (consisting of physical separation between processor and memory units) by slowing down their performance and consuming high power. ,− As a result, new computer designs and materials are being thoroughly investigated to potentially replace existing data storage systems.…”

Epitaxial layered Sb2Te3 thin films for memory and neuromorphic applications

“…Recently, two-dimensional (2D) materials including graphene, transition metal chalcogenides (TMDs), hexagonal boron nitride (h-BN) and black phosphorus (BP) have been attracting a lot of attention as building block material in memristive devices [7,8,[14][15][16][17][18][19][20][21][22][23]. Due to their weak intralayer interaction by van der Waals (vdW) forces, 2D materials can be exfoliated to a few layers or even monolayers with dangling bond free surfaces.…”