Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Nanowires grown on graphene have surprising structure

Graphic by
Parsian Mohseni

Schematic representation of phase segregated InGaAs/InAs nanowires grown on graphene and single phase InGaAs nanowires grown on a different substrate
Graphic by Parsian Mohseni

Schematic representation of phase segregated InGaAs/InAs nanowires grown on graphene and single phase InGaAs nanowires grown on a different substrate

Abstract:
When a team of University of Illinois engineers set out to grow nanowires of a compound semiconductor on top of a sheet of graphene, they did not expect to discover a new paradigm of epitaxy.

Nanowires grown on graphene have surprising structure

Champaign, IL | Posted on April 22nd, 2013

The self-assembled wires have a core of one composition and an outer layer of another, a desired trait for many advanced electronics applications. Led by professor Xiuling Li, in collaboration with professors Eric Pop and Joseph Lyding, all professors of electrical and computer engineering, the team published its findings in the journal Nano Letters.

Nanowires, tiny strings of semiconductor material, have great potential for applications in transistors, solar cells, lasers, sensors and more.

"Nanowires are really the major building blocks of future nano-devices," said postdoctoral researcher Parsian Mohseni, first author of the study. "Nanowires are components that can be used, based on what material you grow them out of, for any functional electronics application."

Li's group uses a method called van der Waals epitaxy to grow nanowires from the bottom up on a flat substrate of semiconductor materials, such as silicon. The nanowires are made of a class of materials called III-V (three-five), compound semiconductors that hold particular promise for applications involving light, such as solar cells or lasers.

The group previously reported growing III-V nanowires on silicon. While silicon is the most widely used material in devices, it has a number of shortcomings. Now, the group has grown nanowires of the material indium gallium arsenide (InGaAs) on a sheet of graphene, a 1-atom-thick sheet of carbon with exceptional physical and conductive properties.

Thanks to its thinness, graphene is flexible, while silicon is rigid and brittle. It also conducts like a metal, allowing for direct electrical contact to the nanowires. Furthermore, it is inexpensive, flaked off from a block of graphite or grown from carbon gases.

"One of the reasons we want to grow on graphene is to stay away from thick and expensive substrates," Mohseni said. "About 80 percent of the manufacturing cost of a conventional solar cell comes from the substrate itself. We've done away with that by just using graphene. Not only are there inherent cost benefits, we're also introducing functionality that a typical substrate doesn't have."

The researchers pump gases containing gallium, indium and arsenic into a chamber with a graphene sheet. The nanowires self-assemble, growing by themselves into a dense carpet of vertical wires across the surface of the graphene. Other groups have grown nanowires on graphene with compound semiconductors that only have two elements, but by using three elements, the Illinois group made a unique finding: The InGaAs wires grown on graphene spontaneously segregate into an indium arsenide (InAs) core with an InGaAs shell around the outside of the wire.

"This is unexpected," Li said. "A lot of devices require a core-shell architecture. Normally you grow the core in one growth condition and change conditions to grow the shell on the outside. This is spontaneous, done in one step. The other good thing is that since it's a spontaneous segregation, it produces a perfect interface."

So what causes this spontaneous core-shell structure? By coincidence, the distance between atoms in a crystal of InAs is nearly the same as the distance between whole numbers of carbon atoms in a sheet of graphene. So, when the gases are piped into the chamber and the material begins to crystallize, InAs settles into place on the graphene, a near-perfect fit, while the gallium compound settles on the outside of the wires. This was unexpected, because normally, with van der Waals epitaxy, the respective crystal structures of the material and the substrate are not supposed to matter.

"We didn't expect it, but once we saw it, it made sense," Mohseni said.

In addition, by tuning the ratio of gallium to indium in the semiconductor cocktail, the researchers can tune the optical and conductive properties of the nanowires.

Next, Li's group plans to make solar cells and other optoelectronic devices with their graphene-grown nanowires. Thanks to both the wires' ternary composition and graphene's flexibility and conductivity, Li hopes to integrate the wires in a broad spectrum of applications.

"We basically discovered a new phenomenon that confirms that registry does count in van der Waals epitaxy," Li said.

This work was supported in part by the Department of Energy and the National Science Foundation. Postdoctoral researcher Ashkan Behnam and graduate students Joshua Wood and Christopher English also were co-authors of the paper. Li also is affiliated with the Beckman Institute for Advanced Science and Technology, the Micro and Nanotechnology Lab, and the Frederick Seitz Materials Research Lab, all at the U. of I.

####

For more information, please click here

Contacts:
Liz Ahlberg
Physical Sciences Editor
217-244-1073


Xiuling Li
217-265-6354

Copyright © University of Illinois at Urbana-Champaign

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

The paper, InxGa1xAs Nanowire Growth on Graphene: van der Waals Epitaxy Induced Phase Segregation, is available online:

Related News Press

News and information

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

Nanoparticles could allow for faster, better medicine: Exposure of nanoparticles in the body allows for more effective delivery November 20th, 2017

Graphene/ Graphite

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Wrinkles give heat a jolt in pillared graphene : Rice University researchers test 3-D carbon nanostructures' thermal transport abilities November 2nd, 2017

Graphene enables high-speed electronics on flexible materials: A flexible terahertz detector has been developed by Chalmers using graphene transistors on plastic substrates. It is the first of its kind, and may open for applications requiring flexible electronics such as wireless October 31st, 2017

Graphene forged into three-dimensional shapes September 26th, 2017

Govt.-Legislation/Regulation/Funding/Policy

EC Project Aims at Creating and Commercializing Cyber-Physical-System Solutions November 14th, 2017

Nanobiotix presented new clinical and pre-clinical data confirming NBTXR3s significant potential role in Immuno-Oncology at SITC Annual Meeting November 14th, 2017

Leti Joins DARPA-Funded Project to Develop Implantable Device for Restoring Vision November 9th, 2017

Nanoshells could deliver more chemo with fewer side effects: In vitro study verifies method for remotely triggering release of cancer drugs November 8th, 2017

Chip Technology

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Nanometrics to Participate in the 6th Annual NYC Investor Summit 2017 November 16th, 2017

Self Assembly

Physicists gain new insights into nanosystems with spherical confinement: Enormous potential for the targeted delivery of pharmaceutical agents and the creation of tailored nanoparticles July 27th, 2017

Oddball enzyme provides easy path to synthetic biomaterials May 17th, 2017

Nanotubes that build themselves April 14th, 2017

Nanocages for gold particles: what is happening inside? March 16th, 2017

Optical computing/Photonic computing

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Practical superconducting nanowire single photon detector with record detection efficiency over 90 percent November 9th, 2017

Metal-silicone microstructures could enable new flexible optical and electrical devices: Laser-based method creates force-sensitive, flexible microstructures that conduct electricity November 1st, 2017

Researchers bring optical communication onto silicon chips: Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers October 23rd, 2017

Nanoelectronics

GLOBALFOUNDRIES, Fudan Team to Deliver Next Generation Dual Interface Smart Card November 14th, 2017

Leti Will Present 11 Papers and Host More-than-Moore Technologies Workshop November 14th, 2017

The next generation of power electronics? Gallium nitride doped with beryllium: How to cut down energy loss in power electronics? The right kind of doping November 9th, 2017

Researchers bring optical communication onto silicon chips: Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers October 23rd, 2017

Discoveries

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Nanoparticles could allow for faster, better medicine: Exposure of nanoparticles in the body allows for more effective delivery November 20th, 2017

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Announcements

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Nano-watch has steady hands November 21st, 2017

Nano Global, Arm Collaborate on Artificial Intelligence Chip to Drive Health Revolution by Capturing and Analyzing Molecular Data in Real Time November 21st, 2017

Nanoparticles could allow for faster, better medicine: Exposure of nanoparticles in the body allows for more effective delivery November 20th, 2017

Energy

Inorganic-organic halide perovskites for new photovoltaic technology November 6th, 2017

Dendritic fibrous nanosilica: all-in-one nanomaterial for energy, environment and health November 4th, 2017

New nanomaterial can extract hydrogen fuel from seawater: Hybrid material converts more sunlight and can weather seawater's harsh conditions October 4th, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

Photonics/Optics/Lasers

Quantum optics allows us to abandon expensive lasers in spectroscopy: Lomonosov Moscow State University scientists have invented a new method of spectroscopy November 21st, 2017

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

Practical superconducting nanowire single photon detector with record detection efficiency over 90 percent November 9th, 2017

Metal-silicone microstructures could enable new flexible optical and electrical devices: Laser-based method creates force-sensitive, flexible microstructures that conduct electricity November 1st, 2017

Solar/Photovoltaic

Inorganic-organic halide perovskites for new photovoltaic technology November 6th, 2017

New nanomaterial can extract hydrogen fuel from seawater: Hybrid material converts more sunlight and can weather seawater's harsh conditions October 4th, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project