skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Sulfurization Engineering of One‐Step Low‐Temperature MoS 2 and WS 2 Thin Films for Memristor Device Applications
Abstract 2D materials have been of considerable interest as new materials for device applications. Non‐volatile resistive switching applications of MoS2and WS2have been previously demonstrated; however, these applications are dramatically limited by high temperatures and extended times needed for the large‐area synthesis of 2D materials on crystalline substrates. The experimental results demonstrate a one‐step sulfurization method to synthesize MoS2and WS2at 550 °C in 15 min on sapphire wafers. Furthermore, a large area transfer of the synthesized thin films to SiO2/Si substrates is achieved. Following this, MoS2and WS2memristors are fabricated that exhibit stable non‐volatile switching and a satisfactory large on/off current ratio (103–105) with good uniformity. Tuning the sulfurization parameters (temperature and metal precursor thickness) is found to be a straightforward and effective strategy to improve the performance of the memristors. The demonstration of large‐scale MoS2and WS2memristors with a one‐step low‐temperature sulfurization method with simple strategy to tuning can lead to potential applications such as flexible memory and neuromorphic computing.  more » « less
Award ID(s):
1720595
PAR ID:
10474715
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Wiley Online Library
Date Published:
Journal Name:
Advanced Electronic Materials
Volume:
8
Issue:
2
ISSN:
2199-160X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Functional Materials)
    Abstract 2D memristors have demonstrated attractive resistive switching characteristics recently but also suffer from the reliability issue, which limits practical applications. Previous efforts on 2D memristors have primarily focused on exploring new material systems, while damage from the metallization step remains a practical concern for the reliability of 2D memristors. Here, the impact of metallization conditions and the thickness of MoS2films on the reliability and other device metrics of MoS2‐based memristors is carefully studied. The statistical electrical measurements show that the reliability can be improved to 92% for yield and improved by ≈16× for average DC cycling endurance in the devices by reducing the top electrode (TE) deposition rate and increasing the thickness of MoS2films. Intriguing convergence of switching voltages and resistance ratio is revealed by the statistical analysis of experimental switching cycles. An “effective switching layer” model compatible with both monolayer and few‐layer MoS2, is proposed to understand the reliability improvement related to the optimization of fabrication configuration and the convergence of switching metrics. The Monte Carlo simulations help illustrate the underlying physics of endurance failure associated with cluster formation and provide additional insight into endurance improvement with device fabrication optimization. 
    more » « less
  2. ; ; ; ; (, Advanced Materials Interfaces)
    Abstract Nanohybrids based on van der Waals (vdW) heterostructures of two dimensional (2D) atomic materials have recently emerged as a unique scheme for designing high‐performance quantum sensors. This work explores vdW nanohybrids for photodetection, which consist of graphene decorated with intermingled transition‐metal dichalcogenide (TMDC) nanodiscs (TMDC‐NDs) obtained using wafer‐size, layer‐by‐layer growth. The obtained TMDC‐NDs/graphene nanohybrids take advantage of strong quantum confinement in graphene for high charge mobility and hence high photoconductive gain, and localized surface plasmonic resonance (LSPR) enabled on the TMDC‐NDs for enhanced light absorption. Since the LSPR depends on the nanostructure's size and density, intermingled TMDC‐NDs of different kinds of TMDCs, such as WS2(W) and MoS2(M), have been found to allow small‐size, high‐concentration TMDC‐NDs to be achieved for high photoresponse. Remarkably, high photoresponsivity up to 31 A/W (550 nm wavelength and 20 µW cm−2light intensity) has been obtained on the WMW‐NDs/graphene nanohybrids photodetectors made using three consecutive coatings of WS2(1st and 3rd coating) and MoS2(2nd coating), which is considerably higher by a factor of ≈4 than that of the counterparts MoS2‐ND/graphene or WS2‐NDs/graphene devices. This result provides a facile approach to control the size and concentration of the TMDC‐NDs for high‐performance, low‐cost optoelectronic device applications. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Nanoscale)
    Low temperature synthesis of high quality two-dimensional (2D) materials directly on flexible substrates remains a fundamental limitation towards scalable realization of robust flexible electronics possessing the unique physical properties of atomically thin structures. Herein, we describe room temperature sputtering of uniform, stoichiometric amorphous MoS 2 and subsequent large area (>6.25 cm 2 ) photonic crystallization of 5 nm 2H-MoS 2 films in air to enable direct, scalable fabrication of ultrathin 2D photodetectors on stretchable polydimethylsiloxane (PDMS) substrates. The lateral photodetector devices demonstrate an average responsivity of 2.52 μW A −1 and a minimum response time of 120 ms under 515.6 nm illumination. Additionally, the surface wrinkled, or buckled, PDMS substrate with conformal MoS 2 retained the photoconductive behavior at tensile strains as high as 5.72% and over 1000 stretching cycles. The results indicate that the photonic crystallization method provides a significant advancement in incorporating high quality semiconducting 2D materials applied directly on polymer substrates for wearable and flexible electronic systems. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Science Advances)
    Resistive switching devices are promising candidates for the next generation of nonvolatile memory and neuromorphic computing applications. Despite the advantages in retention and on/off ratio, filamentary-based memristors still suffer from challenges, particularly endurance (flash being a benchmark system showing 104to 106 cycles) and uniformity. Here, we use WO3as a complementary metal-oxide semiconductor–compatible switching oxide and demonstrate a proof-of-concept materials design approach to enhance endurance and device-to-device uniformity in WO3-based memristive devices while preserving other performance metrics. These devices show stable resistive switching behavior with >106 cycles, >105-second retention, >10 on/off ratio, and good device-to-device uniformity, without using current compliance. All these metrics are achieved using a one-step pulsed laser deposition process to create self-assembled nanocomposite thin films that have regular guided filaments of ≈100-nanometer pitch, preformed between WO3grains and interspersed smaller Ce2O3grains. 
    more » « less
  5. ; ; ; ; ; ; (, ACS Nanoscience Au)
    We report the effects of screening capacity, surface roughness, and interfacial epitaxy of the bottom electrodes on the polarization switching, domain wall (DW) roughness, and ferroelectric Curie temperature (TC) of PbZr0.2Ti0.8O3 (PZT)-based free-standing membranes. Singe crystalline 10−50 nm (001) PZT and PZT/La0.67Sr0.33MnO3 (LSMO) membranes are prepared on Au, correlated oxide LSMO, and two-dimensional (2D) semiconductor MoS2 base layers. Switching the polarization of PZT yields nonvolatile current modulation in the MoS2 channel at room temperature, with an on/off ratio of up to 2 × 105 and no apparent decay for more than 3 days. Piezoresponse force microscopy studies show that the coercive field Ec for the PZT membranes varies from 0.75 to 3.0 MV cm-1 on different base layers and exhibits strong polarization asymmetry. The PZT/LSMO membranes exhibit significantly smaller Ec, with the samples transferred on LSMO showing symmetric Ec of about −0.26/+0.28 MV cm-1, smaller than that of epitaxial PZT films. The DW roughness exponent ζ points to 2D random bond disorder dominated DW roughening (ζ = 0.31) at room temperature. Upon thermal quench at progressively higher temperatures, ζ values for PZT membranes on Au and LSMO approach the theoretical value for 1D random bond disorder (ζ = 2/3), while samples on MoS2 exhibits thermal roughening (ζ = 1/2). The PZT membranes on Au, LSMO, and MoS2 show TC of about 763 ± 12, 725 ± 25, and 588 ± 12 °C, respectively, well exceeding the bulk value. Our study reveals the complex interplay between the electrostatic and mechanical boundary conditions in determining ferroelectricity in free-standing PZT membranes, providing important material parameters for the functional design of PZT-based flexible nanoelectronics. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email