#Black phosphorus surges ahead of graphene A Korean team of scientists tune black phosphorus's band gap to form a superior conductor,
The natural successor to Graphene? Credit: Institute for Basic Science To truly understand the significance of the team findings,
a layered form of carbon atoms constructed to resemble honeycomb, called graphene. Graphene was heralded globally as a wonder-material thanks to the work of two British scientists who won the Nobel prize for Physics for their research on it.
Graphene is extremely thin and has remarkable attributes. It is stronger than steel yet many times lighter
more conductive than copper and more flexible than rubber. All these properties combined make it a tremendous conductor of heat and electricity.
graphene has no band gap. Stepping stones to a Unique State A material band gap is fundamental to determining its electrical conductivity.
Graphene has a band gap of zero in its natural state, however, and so acts like a conductor;
Like graphene, BP is a semiconductor and also cheap to mass produce. The one big difference between the two is BP natural band gap
therefore we tuned BP band gap to resemble the natural state of graphene, a unique state of matter that is different from conventional semiconductors.
This is already an innovation over attempts in the field that use graphene: DNA is a fairly sticky molecule
and Mos2 is considerably less adhesive than graphene. The team then created a nanopore on membrane, almost 3 nm wide.
novel carbon materials like graphene have attracted much attention due to their large surface area, low-cost fabrication, and interaction with a wide range of biomolecules.
the commercially available chip with carboxymethylated dextran (CMD) layer and the chip covered by monolayer graphene.
and this method provides a straightforward way to make semiconducting nanoscale circuits from graphene, a form of carbon only one atom thick.
when graphene grows on germanium, it naturally forms nanoribbons with these very smooth, armchair edges,"said Michael Arnold, an associate professor of materials science and engineering at UW-Madison."
"Graphene, a one-atom-thick, two-dimensional sheet of carbon atoms, is known for moving electrons at lightning speed across its surface without interference.
As a semimetal, graphene naturally has no band-gaps, making it a challenge for widespread industry adoption.
graphene and it shows some characteristic electronic properties, "said Kiraly.""What's even more interesting is that these nanoribbons can be made to grow in certain directions on one side of the germanium crystal,
and graphene that may play a role e
#Graphene flakes as an ultra-fast stopwatch Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), working with colleagues from the USA and Germany, have developed a new optical detector from graphene
which reacts very rapidly to incident light of all different wavelengths and even works at room temperature.
The HZDR scientists are already using the new graphene detector for the exact synchronization of laser systems.
A tiny flake of graphene on silicon carbide and a futuristic-looking antenna and there it is the new graphene detector.
Like no other single detector system which has gone before, this comparatively simple and inexpensive construct can cover the enormous spectral range from visible light all the way to terahertz radiation."
"In contrast to other semiconductors like silicon or gallium arsenide, graphene can pick up light with a very large range of photon energies and convert it into electric signals.
had developed the precursor to the graphene detector. In his present position as a postdoc at the University of Maryland
the graphene flake and antenna assembly absorbs the rays, thereby transferring the energy of the photons to the electrons in the graphene.
These"hot electrons"increase the electrical resistance of the detector and generate rapid electric signals. The detector can register incident light in just 40 picoseconds these are billionths of a second.
So the scientists are using the graphene detector like a stopwatch. It tells them when the laser pulses reach their goal,
The external antenna on the detector captures long-wave infrared and terahertz radiation and funnels it to a graphene flake
#Graphene flakes as an ultra-fast stopwatch Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), working with colleagues from the USA and Germany, have developed a new optical detector from graphene
The HZDR scientists are already using the new graphene detector for the exact synchronization of laser systems.
A tiny flake of graphene on silicon carbide and a futuristic-looking antenna and there it is the new graphene detector.
Like no other single detector system which has gone before, this comparatively simple and inexpensive construct can cover the enormous spectral range from visible light all the way to terahertz radiation."
"In contrast to other semiconductors like silicon or gallium arsenide, graphene can pick up light with a very large range of photon energies and convert it into electric signals.
had developed the precursor to the graphene detector. In his present position as a postdoc at the University of Maryland
the graphene flake and antenna assembly absorbs the rays, thereby transferring the energy of the photons to the electrons in the graphene.
These"hot electrons"increase the electrical resistance of the detector and generate rapid electric signals. The detector can register incident light in just 40 picoseconds these are billionths of a second.
So the scientists are using the graphene detector like a stopwatch. It tells them when the laser pulses reach their goal,
Graphene-nanotube hybrid switches But together, these two materials make a workable digital switch, which is the basis for controlling electrons in computers, phones, medical equipment and other electronics.
Yoke Khin Yap, a professor of physics at Michigan Technological University, has worked with a research team that created these digital switches by combining graphene and boron nitride nanotubes.
Nanoscale Tweaks Graphene is a molecule-thick sheet of carbon atoms; the nanotubes are made like straws of boron and nitrogen.
Yap and his team exfoliate graphene and modify the material's surface with tiny pinholes.
graphene's flat sheet conducts electricity quickly, and the atomic structure in the nanotubes halts electric currents.
and off is several orders of magnitude greater than current graphene switches. In turn, this speed could eventually quicken the pace of electronics and computing.
the use of graphene and nanotubes bypasses those problems. In addition, the graphene and boron nitride nanotubes have the same atomic arrangement pattern,
or lattice matching. With their aligned atoms, the graphene-nanotube digital switches could avoid the issues of electron scattering."
"You want to control the direction of the electrons, "Yap explains, comparing the challenge to a pinball machine that traps,
or change the pinball setup of graphene to minimize electron scattering. And one day, all their tweaks could make for faster computers--and digital pinball games--for the rest of us s
Applying voltage to a 250-nanometer-thick sandwich of graphene, tantalum, nanoporous tantalum oxide and platinum creates addressable bits where the layers meet.
"The layered structure consists of tantalum, nanoporous tantalum oxide and multilayer graphene between two platinum electrodes.
The voltage-controlled movement of oxygen vacancies shifts the boundary from the tantalum/tantalum oxide interface to the tantalum oxide/graphene interface."
The graphene does double duty as a barrier that keeps platinum from migrating into the tantalum oxide and causing a short circuit.
Graphene, an atom-thick material with extraordinary properties, is a promising candidate for the next generation of dramatically faster, more energy-efficient electronics.
that could enable the use of graphene in high-performance semiconductor electronics. Now, University of Wisconsin-Madison engineers have discovered a way to grow graphene nanoribbons with desirable semiconducting properties directly on a conventional germanium semiconductor wafer.
Graphene, a sheet of carbon atoms that is only one atom in thickness, conducts electricity and dissipates heat much more efficiently than silicon,
But to exploit graphene's remarkable electronic properties in semiconductor applications where current must be switched on and off
Researchers have fabricated typically nanoribbons by using lithographic techniques to cut larger sheets of graphene into ribbons.
where they form graphene. Arnold's team made its discovery when it explored dramatically slowing the growth rate of the graphene crystals by decreasing the amount of methane in the chemical vapor deposition chamber.
They found that at a very slow growth rate, the graphene crystals naturally grow into long nanoribbons on a specific crystal facet of germanium.
By simply controlling the growth rate and growth time, the researchers can easily tune the nanoribbon width be to less than 10 nanometers."
when graphene grows on germanium, it naturally forms nanoribbons with these very smooth, armchair edges,
This is already an innovation over attempts in the field that use graphene: DNA is a fairly sticky molecule
and Mos2 is considerably less adhesive than graphene. The team then created a nanopore on membrane, almost 3 nm wide.
it is possible to image individual tobacco mosaic virions deposited on ultraclean freestanding graphene, "said Jean-Nicolas Longchamp, the primary author and a postdoctoral fellow of the Physics department at the University of Zurich, Switzerland."
In Longchamp's experiment, the tobacco mosaic virions were deposited on a freestanding, ultraclean graphene, an atomically thin layer of carbon atoms arranged in a honeycomb lattice.
The graphene substrate is similar to a glass slide in optical microscopy which is conductive, robust and transparent for low energy electrons.
#Graphene teams up with two-dimensional crystals for faster data communications Ultra-fast detection of light lies at the heart of optical communication systems nowadays.
combined with graphene, has the capability to detect optical pulses with a response faster than ten picoseconds,
An important advantage of these devices based on graphene and other two-dimensional materials is that they can be integrated monolithically with silicon photonics enabling a new class of photonic integrated circuits.
"ICFO researcher Mathieu Massicotte and first author of this study states that"Everyone knew graphene could make ultrafast photodetectors,
"The results obtained from this study have shown that the stacking of semiconducting 2d materials with graphene in heterostructures could lead to new, fast and efficient optoelectronic applications,
"In a way, the most exciting aspect of this work is that it should be applicable to a wide range of nanoscale materials such as complex oxides, graphene,
A Graphene Cytobot"."""We've taken a spore from a bacteria, and put graphene quantum dots on its surface
#Desalination with nanoporous graphene membrane Less than 1 percent of Earth's water is drinkable. Removing salt and other minerals from our biggest available source of water--seawater--may help satisfy a growing global population thirsty for fresh water for drinking, farming, transportation, heating, cooling and industry.
Now, a team of experimentalists led by the Department of energy's Oak ridge National Laboratory has demonstrated an energy-efficient desalination technology that uses a porous membrane made of strong, slim graphene--a carbon honeycomb one atom thick.
Making pores in the graphene is key. Without these holes, water cannot travel from one side of the membrane to the other.
The water molecules are simply too big to fit through graphene's fine mesh. But poke holes in the mesh that are just the right size
"Graphene to the rescue Graphene is only one-atom thick, yet flexible and strong. Its mechanical and chemical stabilities make it promising in membranes for separations.
"If we can use this single layer of graphene, we could then increase the flux
To make graphene for the membrane, the researchers flowed methane through a tube furnace at 1,
The researchers transferred the graphene membrane to a silicon nitride support with a micrometer-sized hole.
Then the team exposed the graphene to an oxygen plasma that knocked carbon atoms out of the graphene's nanoscale chicken wire lattice to create pores.
The longer the graphene membrane was exposed to the plasma, the bigger the pores that formed,
The silicon nitride chip held the graphene membrane in place while water flowed through it from one chamber to the other.
allowed for atom-resolution imaging of graphene, which the scientists used to correlate the porosity of the graphene membrane with transport properties.
They determined the optimum pore size for effective desalination was 0. 5 to 1 nanometers,
#Graphene pushes the speed limit of light-to-electricity conversion (Nanowerk News) The efficient conversion of light into electricity plays a crucial role in many technologies,
Graphene is an excellent material for ultrafast conversion of light to electrical signals, but so far it was known not how fast graphene responds to ultrashort flashes of light.
ICFO researchers Klaas-Jan Tielrooij Lukasz Piatkowski, Mathieu Massicotte and Achim Woessner led by ICFO Prof.
have demonstrated now that a graphene-based photodetector converts absorbed light into an electrical voltage at an extremely high speed.
The study, entitled"Generation of photovoltage in graphene on a femtosecond timescale through efficient carrier heating",has recently been published in Nature Nanotechnology("Generation of photovoltage in graphene on a femtosecond timescale through efficient carrier heating".
Facilitated by graphene's nonlinear photo-thermoelectric response, these elements enabled the observation of femtosecond photodetection response times."
"The ultrafast creation of a photovoltage in graphene is possible due to the extremely fast and efficient interaction between all conduction band carriers in graphene.
Next, the electron heat is converted into a voltage at the interface of two graphene regions with different doping.
"it is amazing how graphene allows direct nonlinear detecting of ultrafast femtosecond (fs) pulses"."The results obtained from the findings of this work,
which has been funded partially by the EC Graphene Flagship, open a new pathway towards ultra-fast optoelectronic conversion.
Koppens comments,"Graphene photodetectors keep showing fascinating performances addressing a wide range of applications
#Lanthanide-organic framework nanothermometers prepared by spray-drying A work in Advanced Functional Materials shows how spray-drying prepared MOF nanoparticles containing lanthanide metals may be used as nanothermometers operative over a wide range of temperatures
#Researchers create first whispering gallery for graphene electrons (Nanowerk News) An international research group led by scientists at the U s. Commerce departments National Institute of Standards
and Technology (NIST) has developed a technique for creating nanoscale whispering galleries for electrons in graphene. The development opens the way to building devices that focus
issue of Science("Creating and probing electron whispering-gallery modes in graphene")."An international research group led by scientists at NIST has developed a technique for creating nanoscale whispering galleries for electrons in graphene.
The researchers used the voltage from a scanning tunneling microscope (right) to push graphene electrons out of a nanoscale area to create the whispering gallery (represented by the protuberances on the left),
which is like a circular wall of mirrors to the electron. Image: Jon Wyrick, CNST/NIST) In some structures,
Ever since graphene, a single layer of carbon atoms arranged in a honeycomb lattice, was created first in 2004,
However, early studies of the behavior of electrons in graphene were hampered by defects in the material.
As the manufacture of clean and near-perfect graphene becomes more routine, scientists are beginning to uncover its full potential.
Due to the light-like properties of graphene electrons, they can pass through unimpededno matter how high the barrierif they hit the barrier head on.
This tendency to tunnel makes it hard to steer electrons in graphene. Enter the graphene electron whispering gallery.
To create a whispering gallery in graphene the team first enriched the graphene with electrons from a conductive plate mounted below it.
With the graphene now crackling with electrons, the research team used the voltage from a scanning tunneling microscope (STM) to push some of them out of a nanoscale-sized area.
This created the whispering gallery, which is like a circular wall of mirrors to the electron.
An electron that hits the step head-on can tunnel straight through it, said NIST researcher Nikolai Zhitenev.
A team of theoretical physicists from the Massachusetts institute of technology developed the theory describing whispering gallery modes in graphene.
Graphene-based quantum electronic resonators and lenses have as yet untold potential but if conventional optics is any guide,
#Combining graphene and nanotubes to make digital switches Graphene has been called a wonder material, capable of performing great and unusual material acrobatics.
As a conductor, graphene lets electrons zip too fasthere no controlling or stopping themhile boron nitride nanotubes are
Yoke Khin Yap, a professor of physics at Michigan Technological University, has worked with a research team that created these digital switches by combining graphene and boron nitride nanotubes.
The journal Scientific Reports recently published their work("Switching Behaviors of Graphene-Boron nitride nanotube Heterojunctions"."he question is:
Nanoscale Tweaks Graphene is a molecule-thick sheet of carbon atoms; the nanotubes are made like straws of boron and nitrogen.
Yap and his team exfoliate graphene and modify the material surface with tiny pinholes. Then they can grow the nanotubes up and through the pinholes.
graphene flat sheet conducts electricity quickly, and the atomic structure in the nanotubes halts electric currents.
and off is several orders of magnitude greater than current graphene switches. In turn, this speed could eventually quicken the pace of electronics and computing.
the use of graphene and nanotubes bypasses those problems. In addition, the graphene and boron nitride nanotubes have the same atomic arrangement pattern,
or lattice matching. With their aligned atoms, the graphene-nanotube digital switches could avoid the issues of electron scattering. ou want to control the direction of the electrons,
Yap explains, comparing the challenge to a pinball machine that traps, slows down and redirects electrons. his is difficult in high speed environments,
or change the pinball setup of graphene to minimize electron scattering. And one day all their tweaks could make for faster computersnd digital pinball gamesor the rest of us t
#Using lasers to tailor the properties of graphene Carbon nanomaterials display extraordinary physical properties, outstanding among any other substance available,
and Graphene has grown as the most promising material for brand-new electronic circuitry, sensors and optical communications devices.
Graphene is a single atomic-thick sheet of honeycomb carbon lattice, with unique electronic and optical properties,
But two problems hinder graphene's uptake in real world electronics. There is no large-scale technology to control the properties,
and the traditional technology used for silicon-based processors (solid state) is not suitable for graphene processing (molecular material).
The researchers from Technological Center AIMEN explore the use of ultrafast lasers as tool for graphene processing.
For this timescale, researches demonstrated that they can pattern graphene lattice by cutting adding external molecules or binding compounds (functional groups like oxygen or hydroxyl.
direct writing of devices on graphene can be done with high precision, producing nanodevices with minimal footprint and maximum efficiency.
As recently published in AIP Applied Physics Letters("Patterned graphene ablation and two-photon functionalization by picosecond laser pulses in ambient conditions),
"the work of AIMEN researches demonstrated laser based large scale patterning of graphene at high speed and resolution, opening new possibilities for device making.
and atmosphere molecules, resulting in new optical properties in graphene. The potential of the altered optical properties (like spectral transmission) of functionalized graphene are just starting to be recognized,
and the full industrial potential of this technology needs to be tackled. This research work lays a foundation for deep understanding of the chemical and physical processes for industrially feasible graphene patterning,
as well as tests in real device application for future electronics. About AIMEN Located in Northwestern Spain
Applying voltage to a 250-nanometer-thick sandwich of graphene, tantalum, nanoporous tantalum oxide and platinum creates addressable bits where the layers meet.
A schematic shows the layered structure of tantalum oxide, multilayer graphene and platinum used for a new type of memory developed at Rice university.
"The layered structure consists of tantalum, nanoporous tantalum oxide and multilayer graphene between two platinum electrodes.
The voltage-controlled movement of oxygen vacancies shifts the boundary from the tantalum/tantalum oxide interface to the tantalum oxide/graphene interface."
The graphene does double duty as a barrier that keeps platinum from migrating into the tantalum oxide and causing a short circuit.
#Black phosphorus surges ahead of graphene A Korean team of scientists tune BP's band gap to form a superior conductor,
a layered form of carbon atoms constructed to resemble honeycomb, called graphene. Graphene was heralded globally as a wonder-material thanks to the work of two British scientists who won the Nobel prize for Physics for their research on it.
Graphene is extremely thin and has remarkable attributes. It is stronger than steel yet many times lighter
more conductive than copper and more flexible than rubber. All these properties combined make it a tremendous conductor of heat and electricity.
graphene has no band gap. Stepping stones to a Unique State A material's band gap is fundamental to determining its electrical conductivity.
Graphene has a band gap of zero in its natural state, however, and so acts like a conductor;
Like graphene, BP is a semiconductor and also cheap to mass produce. The one big difference between the two is BP's natural band gap
"Graphene is a Dirac semimetal. It's more efficient in its natural state than black phosphorus
therefore we tuned BP's band gap to resemble the natural state of graphene, a unique state of matter that is different from conventional semiconductors."
Prior to their discovery, graphene, which is a single sheet of carbon atoms, was the first two-dimensional material to be touted for its potential energy storage capabilities.
graphene was difficult to modify in form and therefore had limited energy storage capabilities. The new MXENES have surfaces that can store more energy.
#Pillared graphene gains strength Rice university researchers discovered that putting nanotube pillars between sheets of graphene could create hybrid structures with a unique balance of strength, toughness and ductility throughout all three dimensions.
particularly between carbon nanotubes and graphene, would affect the final hybrid properties in all directions. They found that introducing junctions would add extra flexibility
graphene is a rolled out sheet of the same. Both are super-strong and excel at transmitting electrons and heat.
and quantitatively predict the properties of hybrid versions of graphene and nanotubes. These hybrid structures impart new properties
and functionality that are absent in their parent structures graphene and nanotubes. To that end the lab assembled three-dimensional computer models of illared graphene nanostructures, akin to the boron nitride structures modeled in a previous study to analyze heat transfer between layers. his time we were interested in a comprehensive understanding of the elastic and inelastic properties
of 3-D carbon materials to test their mechanical strength and deformation mechanisms, Shahsavari said. e compared our 3-D hybrid structures with the properties of 2-D stacked graphene sheets and 1-D carbon nanotubes.
Layered sheets of graphene keep their properties in-plane, but exhibit little stiffness or thermal conductance from sheet to sheet,
But pillared graphene models showed far better strength and stiffness and a 42 percent improvement in out-of-plane ductility,
The latter allows pillared graphene to exhibit remarkable toughness along out-of-plane directions, a feature that is not possible in 2-D stacked graphene sheets or 1-D carbon nanotubes,
made of graphite with additional compounds bonded to the edges of two-dimensional sheets of graphene that make up the material.
novel carbon materials like graphene have attracted much attention due to their large surface area, low-cost fabrication, and interaction with a wide range of biomolecules.
the commercially available chip with carboxymethylated dextran (CMD) layer and the chip covered by monolayer graphene.
#Big range of behaviors for tiny graphene pores The surface of a single cell contains hundreds of tiny pores,
Now researchers at MIT have created tiny pores in single sheets of graphene that have an array of preferences and characteristics similar to those of ion channels in living cells.
Each graphene pore is less than 2 nanometers wide, making them among the smallest pores through
Karnik reasoned that graphene would be a suitable material in which to create artificial ion channels:
A sheet of graphene is an ultrathin lattice of carbon atoms that is one atom thick, so pores in graphene are defined at the atomic scale.
To create pores in graphene, the group used chemical vapor deposition, a process typically used to produce thin films.
In graphene, the process naturally creates tiny defects. The researchers used the process to generate nanometer-sized pores in various sheets of graphene,
which bore a resemblance to ultrathin Swiss cheese. The researchers then isolated individual pores by placing each graphene sheet over a layer of silicon nitride that had been punctured by an ion beam
the diameter of which is slightly smaller than the spacing between graphene pores. The group reasoned that any ions flowing through the two-layer setup would have passed likely first through a single graphene pore,
and then through the larger silicon nitride hole. The group measured flows of five different salt ions through several graphene sheet setups by applying a voltage and measuring the current flowing through the pores.
The current-voltage measurements varied widely from pore to pore, and from ion to ion, with some pores remaining stable,
which given the single-atom thickness of graphene makes them among the smallest pores through
which require large amounts of pressure to push water through. f these were replaced with graphene,
and will surely guide current and future graphene membrane design principles in years to come. e
next-generation health monitoring devices such as electronic stick-on tattoos (see for instance"wearing single-walled carbon nanotube electronics on your skin",a"temporary tattoo to monitor glucose levels"or"graphene nanosensor tattoo
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