Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > Edgy Look at 2D Molybdenum Disulfide: Berkeley Lab Researchers Observe 1D Edge States Critical to Nanoelectronic and Photonic Applications

A new SHG imaging technique allows rapid and all-optical determination of the crystal orientations of 2D semiconductor membranes at a large scale, providing the knowledge needed to use these materials in nanoelectronic devices.
A new SHG imaging technique allows rapid and all-optical determination of the crystal orientations of 2D semiconductor membranes at a large scale, providing the knowledge needed to use these materials in nanoelectronic devices.

Abstract:
The drive to develop ultrasmall and ultrafast electronic devices using a single atomic layer of semiconductors, such as transition metal dichalcogenides, has received a significant boost. Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have recorded the first observations of a strong nonlinear optical resonance along the edges of a single layer of molybdenum disulfide. The existence of these edge states is key to the use of molybdenum disulfide in nanoelectronics, as well as a catalyst for the hydrogen evolution reaction in fuel cells, desulfurization and other chemical reactions.

Edgy Look at 2D Molybdenum Disulfide: Berkeley Lab Researchers Observe 1D Edge States Critical to Nanoelectronic and Photonic Applications

Berkeley, CA | Posted on May 2nd, 2014

"We observed strong nonlinear optical resonances at the edges of a two-dimensional crystal of molybdenum disulfide" says Xiang Zhang, a faculty scientist with Berkeley Lab's Materials Sciences Division who led this study. "These one-dimensional edge states are the result of electronic structure changes and may enable novel nanoelectronics and photonic devices. These edges have also long been suspected to be the active sites for the electrocatalytic hydrogen evolution reaction in energy applications. We also discovered extraordinary second harmonic light generation properties that may be used for the in situ monitoring of electronic changes and chemical reactions that occur at the one-dimensional atomic edges."

Zhang, who also holds the Ernest S. Kuh Endowed Chair Professor at the University of California (UC) Berkeley, directs the National Science Foundation's Nano-scale Science and Engineering Center, and is a member of the Kavli Energy NanoSciences Institute at Berkeley, is the corresponding author of a paper in Science describing this research. The paper is titled "Edge Nonlinear Optics on a MoS2 Atomic Monolayer." Co-authors are Xiaobo Yin, Ziliang Ye, Daniel Chenet, Yu Ye, Kevin O'Brien and James Hone.

Emerging two-dimensional semiconductors are prized in the electronics industry for their superior energy efficiency and capacity to carry much higher current densities than silicon. Only a single molecule thick, they are well-suited for integrated optoelectronic devices. Until recently, graphene has been the unchallenged superstar of 2D materials, but today there is considerable attention focused on 2D semiconducting crystals that consist of a single layer of transition metal atoms, such as molybdenum, tungsten or niobium, sandwiched between two layers of chalcogen atoms, such as sulfur or selenium. Featuring the same flat hexagonal "honeycombed" structure as graphene and many of the same electrical advantages, these transition metal dichalcogenides, unlike graphene, have direct energy bandgaps. This facilitates their application in transistors and other electronic devices, particularly light-emitting diodes.

Full realization of the vast potential of transition metal dichalcogenides will only come with a better understanding of the domain orientations of their crystal structures that give rise to their exceptional properties. Until now, however, experimental imaging of these three-atom-thick structures and their edges have been limited to scanning tunneling microscopy and transmission electron microscopy, technologies that are often difficult to use. Nonlinear optics at the crystal edges and boundaries enabled Zhang and his collaborators to develop a new imaging technique based on second-harmonic generation (SHG) light emissions that can easily capture the crystal structures and grain orientations with an optical microscope.

"Our nonlinear optical imaging technique is a non-invasive, fast, easy metrologic approach to the study of 2D atomic materials," says Xiaobo Yin, the lead author of the Science paper and a former member of Zhang's research group who is now on the faculty at the University of Colorado, Boulder. "We don't need to prepare the sample on any special substrate or vacuum environment, and the measurement won't perturb the sample during the imaging process. This advantage allows for in-situ measurements under many practical conditions. Furthermore, our imaging technique is an ultrafast measurement that can provide critical dynamic information, and its instrumentation is far less complicated and less expensive compared with scanning tunneling microscopy and transmission electron microscopy."

For the SHG imaging of molybdenum disulfide, Zhang and his collaborators illuminated sample membranes that are only three atoms thick with ultrafast pulses of infrared light. The nonlinear optical properties of the samples yielded a strong SHG response in the form of visible light that is both tunable and coherent. The resulting SHG-generated images enabled the researchers to detect "structural discontinuities" or edges along the 2D crystals only a few atoms wide where the translational symmetry of the crystal was broken.

"By analyzing the polarized components of the SHG signals, we were able to map the crystal orientation of the molybdenum disulfide atomic membrane," says Ziliang Ye, the co-lead author of the paper and current member of Zhang's research group. "This allowed us to capture a complete map of the crystal grain structures, color-coded according to crystal orientation. We now have a real-time, non-invasive tool that allows us explore the structural, optical, and electronic properties of 2D atomic layers of transition metal dichalcogenides over a large area."

This research was supported by the DOE Office of Science through the Energy Frontier Research Center program, and by the U.S. Air Force Office of Scientific Research Multidisciplinary University Research Initiative.

####

About DOE/Lawrence Berkeley National Laboratory
Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

For more information, please click here

Contacts:
Lynn Yarris

510-486-5375

Xiang Zhang
(Mobile): 510-225-8559

Xiaobo Yin
650-796-3276

Ziliang Ye
510-508-6128510-508-6128

Copyright © DOE/Lawrence Berkeley National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

For more about the research of Xiang Zhang go here:

Related News Press

News and information

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Graphene/ Graphite

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

The moiré patterns of three layers change the electronic properties of graphene March 8th, 2019

Imaging

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Lightweight metal foams become bone hard and explosion proof after being nanocoated March 14th, 2019

New optical imaging system could be deployed to find tiny tumors: Near-infrared technology pinpoints fluorescent probes deep within living tissue; may be used to detect cancer earlier March 8th, 2019

Govt.-Legislation/Regulation/Funding/Policy

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Researchers reverse the flow of time on IBM's quantum computer March 14th, 2019

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

Arrowhead Pharmaceuticals Begins Dosing in Phase 1 Study of ARO-APOC3 for Treatment of Hypertriglyceridemia March 11th, 2019

Chip Technology

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Pushing Past Limits: Junkai Jiang receives prestigious Ph.D. Student Fellowship from IEEE Electron Devices Society March 14th, 2019

Nanometrics Announces $80 Million Share Repurchase Program March 14th, 2019

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

Nanoelectronics

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

Zips on the nanoscale: New method of synthesising nanographene on metal oxide surfaces March 5th, 2019

Large, stable pieces of graphene produced with unique edge pattern: Breakthrough in graphene research February 1st, 2019

Kiel physicists discover new effect in the interaction of plasmas with solids January 18th, 2019

Discoveries

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Materials/Metamaterials

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Now made in Japan – Asian battery manufacturers welcome highly conductive nanotube additive March 7th, 2019

Can a flowing liquid-like material maintain its structural order like crystals? February 27th, 2019

Super-light, super-insulating ceramic aerogel keeps the hottest temperatures at bay February 17th, 2019

Announcements

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Tools

Lightweight metal foams become bone hard and explosion proof after being nanocoated March 14th, 2019

Nanometrics Announces $80 Million Share Repurchase Program March 14th, 2019

New optical imaging system could be deployed to find tiny tumors: Near-infrared technology pinpoints fluorescent probes deep within living tissue; may be used to detect cancer earlier March 8th, 2019

New blueprint for understanding, predicting and optimizing complex nanoparticles: Guidelines have the potential to transform the fields of optoelectronics, bio-imaging and energy harvesting March 1st, 2019

Military

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Lightweight metal foams become bone hard and explosion proof after being nanocoated March 14th, 2019

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project