Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Two-Dimensional Layered Materials for High-Performance Electronics

25.05.2012
Graphene is the wonder material that could solve the problem of making ever faster computers and smaller mobile devices when current silicon microchip technology hits an inevitable wall.

Graphene, a single layer of carbon atoms in a tight hexagonal arrangement, is a highly researched material due to its incredible electronic properties, with theoretical speeds 100 times greater than silicon. But putting the material into a microchip that could outperform current silicon technology has proven difficult.

The answer may lie in new nanoscale systems based on ultrathin layers of materials with exotic properties. Called two-dimensional layered materials, these systems could be important for microelectronics, various types of hypersensitive sensors, catalysis, tissue engineering and energy storage. Researchers at Penn State have applied one such 2D layered material, a combination of graphene and hexagonal boron nitride, to produce improved transistor performance at an industrially relevant scale.

“Other groups have shown that graphene on boron nitride can improve performance two to three times, but not in a way that could be scaled up. For the first time, we have been able to take this material and apply it to make transistors at wafer scale,” says Joshua Robinson, assistant professor of materials science and engineering at Penn State and the corresponding author on a paper reporting their work in the online version of the journal ACS Nano.

In the article, the Penn State team describes a method for integrating a thin layer of graphene only one or two atoms thick, with a second layer of hexagonal boron nitride (hBN) with a thickness of a few atoms up to several hundred atoms. The resulting bilayer material constitutes the next step in creating functional graphene field effect transistors for high frequency electronic and optoelectronic devices.

Previous research by other groups has shown that a common material called hexagonal boron nitride (hBN), a synthetic mixture of boron and nitrogen that is used as an industrial lubricant and is found in many cosmetics, is a potential replacement for silicon dioxide and other high-performance dielectrics that have failed to integrate well with graphene. Because boron sits next to carbon on the periodic table, and hexagonal boron nitride has a similar arrangement of atoms as graphene, the two materials match up well electronically. In fact, hBN is often referred to as white graphene. To be of more than academic interest in the lab, however, the hBN-graphene bilayer had to be grown at wafer scale – from around 3 inches (75 mm) to almost 12 inches (300 mm).

The Penn State team solved this problem by using a prior technique developed in their lab to produce a uniform, large-area, and high quality layer of epitaxial graphene suitable for high frequency applications. This “quasi-freestanding epitaxial graphene” was produced by attaching hydrogen atoms to the graphene in order to “passivate dangling bonds,” essentially flattening and smoothing the graphene film. The hexagonal boron nitride was then grown on a transition metal substrate using a chemical vapor deposition technique that is standard in manufacturing. The hBN was released from the substrate via one of several transfer processes and layered on top of the graphene on a 75mm wafer, marking the first integration of epitaxial graphene with hBN on a scale compatible with industry needs.

Building on their earlier work with epitaxial graphene, which had already increased transistor performance by 2-3 times, this research adds a further 2-3x improvement in performance and shows the strong potential for utilizing graphene in electronics, according to Robinson. In the near future, the Penn State team hopes to demonstrate graphene based integrated circuits and high-performance devices suitable for industrial-scale manufacturing on 100mm wafers.

“We use all standard lithography, which is important for nanomanufacturing,” Robinson adds. In order to make a dent in the highly competitive microchip industry, a new material system needs to be compatible with current processing technology as well as offer a significant performance boost.

Boron nitride-graphene is one of several up-and-coming two-dimensional layered systems whose nanoscale properties are only beginning to be discovered. Dimensionality, according to Nobel Laureates Novoselov and Geim, is one of the most defining material parameters and can give rise to dramatically different properties according to whether the material structure is 0D, 1D, 2D, or 3D. Penn State is among the pioneers moving into what may prove to be a new frontier of materials science.

In addition to Robinson, the co-authors on the ACS Nano article are Michael Bresnehan, Matthew Hollander, Maxwell Wetherington, Michael LaBella, Kathleen Trumbull, Randal Cavalero, and David Snyder, all of Penn State. The work was supported by the Naval Surface Warfare Center Crane, and instrumentation support was provided by the National Nanotechnology Infrastructure Network at Penn State. “Integration of Hexagonal Boron Nitride with Quasi-freestanding Epitaxial Graphene: Toward Wafer-Scale High-Performance Devices” was published in online in the April 28, 2012, ASAP (as soon as publishable) edition of ACS Nano. Contact Joshua Robinson at jrobinson@psu.edu.

Joshua Robinson | Newswise Science News
Further information:
http://www.psu.edu

More articles from Materials Sciences:

nachricht New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State

nachricht Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>