Alabama Republican Sen. Jeff Sessions, in an exclusive interview to be broadcast on The Daily Caller on Monday, savages the comprehensive immigration bill currently being debated by Congress.
Sessions, in his measured Alabama drawl, argued that being against the ?Gang of Eight?s? proposed bill does not mean that he is against immigrants or against immigration, but rather that he is against this bill on its merits, and that the bill, upon closer inspection, is more akin to shoe leather than steak.
?People want to vote for a bill that fixes immigration,? Sessions told TheDC. ?They want so desperately to have that to happen. ? The error was that a group of Senators basically turned this over to secret meetings and special interest groups and they didn?t understand the bill fully either.?
Sessions believes that the bill is too fluid and too vacuous ? especially when it comes to the numbers of people that provisions in the bill will affect and how many ?new? citizens will be created.
?The sponsor?s of the bill either don?t know or wont say,? Sessions said.
As recently as five years ago it would have been unthinkable to gather the world's most powerful leaders in Northern Ireland. Things have changed as the G8 summit gets ready to start Monday.
With world leaders gathering in the picturesque backwater of Lough Erne, a major security operation is underway, but locals are hoping the inconvenience will be made-up for by demonstrating the locale's tourism potential in front of the world's press.
The high security ? bomb proof police vans are dotted around the roads and checkpoints are in operation ? is reminiscent of the worst years of the Northern Irish conflict, but the fact that the G8 is being held in Northern Ireland at all marks just how far the state has come.
RECOMMENDED: Keep calm and answer on: Take our United Kingdom quiz.
The location of the conference lies close to Northern Ireland's border with the Republic of Ireland. During the three decade "Troubles," the border was a heavily militarized frontier ? not quite the Cold War-era Inner German Border, but dotted with checkpoints, forts, a heavy police presence, and military patrols nonetheless.
Not anymore. Today drivers have to pay attention otherwise they'll miss it, with the only differences being different colored road markings and speed limits in kilometers per hour in the Republic and miles per hour in the North. Irish police man the usually empty border, but are content to wave through all comers, and seemed shocked when this reporter pulled over to ask questions.
Yards away, inside Northern Ireland's Country Fermanagh the security presence remains minimal until around two miles from the Lough Erne Resort where the world's most powerful people will meet. It is at this point that your reporter was politely turned around and directed to the Siberia of an official press center ? over four miles away.
LOCALS LOOKING FOR BOOST
Hosted by British prime minister David Cameron ? Northern Ireland remains part of the United Kingdom ? the G8, or Group of Eight, is a forum for the governments of the world's largest economies to talk shop. This year, tax, transparency, and trade are on the agenda. As a result the remote, if picturesque, west of Ireland will be a temporary home to figures including President Barack Obama, Russian President Vladimir Putin, Italian Prime Minister Enrico Letta, and German Chancellor Angela Merkel.
The pending arrival of such luminaries for the two-day summit starting Monday has severely discommoded locals, but the area, always remote and now hard-hit by recession, is hoping for an economic boost.
In the immediate term, though, the opposite is happening.
David Hassard, co-owner of Crannog Antiques in Enniskillen, seems reticent to criticize the security operation despite his store being only a few hundred yards from the "ring of steel."
"There's been quite a bit of police activity but it's not inconveniencing things. Our business has been a bit quieter, but I can't say that's because of the G8," he says.
Just across the road from Hassard's boutique, Portora Royal School, once an elite Protestant boarding school that included Irish literary giants Samuel Beckett and Oscar Wilde among its past pupils, is now open to all boys based on academic ability and remains one of Ireland's top schools.
Headmaster Neill Morton, an avuncular, obviously passionate educationalist and native of Belfast, sees the event as positive, but doesn't want to speak on behalf of longstanding residents. He does suggest, though, that the ability to secure the area was a major factor in choosing Enniskillen as the site for the often-protested summit.
"It's fairly easily defended ? it's in the remote west of Ireland, after all. It's very easy to secure the road [and] it's on an island [in Lough Enre] so they'll probably close the bridges," he says.
Northern Ireland, though largely peaceful, remains an unsettled polity and many see David Cameron's decision to hold such high-profile talks here as remarkable ? for more reasons than one.
Enniskillen is best-known internationally as the location of the 1987 Remembrance Day Irish Republican Army (IRA) bombing that resulted in 11 deaths and damaged the IRA's support even among Irish nationalists. This year's massive security operation, which has involved the drafting-in of British police to bolster local numbers, has evoked painful memories for some, but Mr. Morton, for one, sees hope and says Enniskillen is home to a forgiving and changing population.
"There are people who bear scars, but if the town is prosperous it's because of cross-border trade and there are [now] more Catholic students than Protestant students in the town," he says.
Others see the summit as symbolic ? either of peace or of the British premier's staking-out a British claim on Northern Ireland in the face of the electoral success of Irish republicans and a challenge to UK sovereignty from Scottish nationalists.
SOME PROTEST ACTIVITY
Not everyone in Northern Ireland has welcomed the world leaders, though. Saturday saw a series of demonstrations in Belfast.
The largest, a labor movement rally entitled "Another World is Possible," arrived at city hall at midday. Official estimates put the number of protesters at 1,500.
At the other end of the ideological spectrum ? and local political divide ? pro-British loyalists also marshaled at city hall, continuing their protests over the local council's 2012 decision to stop flying the British Union flag 365 days a year. The protests met, but passed-off without confrontation.
Police district commander Chief Superintendent Alan McCrum issued a statement describing his officers work as "a significant policing operation."
An anti-"fracking" demonstration was also held in the city, while "The Big If," a world hunger charity event directed at G8 leaders, was held later in the day.
Last week hard-line republican groups, including Republican Network for Unity, also took to the streets with hammer and sickle flags, with further demonstrations likely.
Back in Enniskillen, Gareth McKeown, a reporter on the Fermanagh Herald ? one of the county's two local newspapers, the other being the impressively named Impartial Reporter ? dismisses naysayers.
"Eleven million pounds were spent on improving the roads ? things like that can only improve things for the people here," he says.
Questioned about the potential for Islamic terrorism, Mr. McKeown simply laughs. More prosaic, but more serious, is the issue of fracking: "It's an almost universally unpopular idea around here," he says.
Protesters realize this and local groups have brought the issue into focus during the summit. Socialist party member Domhnall ? Cobhthaigh, a former local councilor, is helping to organize protests at the Lough Erne Resort.
Mr. ? Cobhthaigh, who expects 2,000 protesters to arrive tonight at 7 p.m., agrees the G8 doesn't have the protester pulling-power it did a decade ago, but say issues like fracking have hit a nerve ? and the G8's free trade agenda makes it relevant.
"The G8 is seeking to make any government's attempt to ban fracking illegal as an anti-market measure," he says.
So far the protests have been low-key, as is the response from residents to fears of terrorism ? from Irish dissidents or global jihadists ? aired by police and politicians.
Instead, the level of security has drawn some criticism, with ? Cobhthaigh saying the strict measures may dissuade some protesters. "The big story here is the threat of drones, night courts, and the thousands of [temporary] jail cells they've built. All these things are building into a story of fear, fear, fear. Being lumped in with dissidents, acid-throwing anarchists, and Islamic terrorists? You have to ask, is protest being criminalized?" he says.
Children are impossible to please, no matter now many Lunchables you ply them with. But even the most ungrateful tykes will appreciate getting one of Mores stunning Petitpierre kids bikes crafted from carbon fiber so they're easier to ride and maneuver.
Featuring everything from built-in LED safety lights, to a clever footrest built into the frame for kids just learning to ride, the bike's curvy design gives it a lower center of gravity which makes mastering the two-wheel balancing act a little easier. And at just under seven pounds kids can easily lift it over curbs or other obstacles they're too small to tackle.
The only catch? A $2,000 price tag that will probably have parents refusing to let their kids actually ride the Petitpierre so that it can be handed down for generations.
In a boost to California's endangered amphibians, researchers released about 100 mountain yellow-legged froglets into the wild this week.
The diminutive frogs were bred and raised in captivity for a year before they were released on Wednesday (June 12) into a creek at the James San Jacinto Mountains Reserve. This is the first time frogs of this species have been reintroduced into the wild, said researcher Frank Santana, of the San Diego Zoo Institute for Conservation Research.
"Right away, they were exhibiting natural behaviors," Santana said in a video from the San Diego Zoo."They swam away, they did these natural anti-predator-behaviors, they went to the bottom of the pool to try to blend in with the substrate ? I think they're well positioned to survive."
Some of the frogs were outfitted with radio telemetry backpacks, which will allow researchers to pinpoint the animals' location and track their wellbeing, Santana added.
The frogs once thrived in streams in parts of the San Gabriel, San Bernardino and San Jacinto mountains in Southern California, but they experienced a precipitous decline over the last several decades; by 2003, there were estimated to be fewer than 200 individuals.
Mountain yellow-legged frogs (Rana muscosa) are listed as endangered by the U.S. Fish and Wildlife Service, and they continue to face environmental threats, including predatory trout introduced to their habitats and the deadly fungal infection chytridiomycosis, which has devastated amphibian populations worldwide.
Follow Megan Gannon on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on LiveScience.com.
Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
VATICAN CITY (AP) -- The Vatican put a new coin on sale last week to commemorate its historic papal transition. Too bad overseas collectors won't be able to buy it for months.
The Associated Press has learned that the Vatican still hasn't fully resolved an embarrassing shutdown in credit card services, despite announcing four months ago that systems were back up. The impact has been far worse than the Vatican ever let on, costing the Holy See lost sales at a time when Pope Benedict XVI's shock resignation and Pope Francis' surprise election laid the groundwork for a bonanza in Vatican-minted papal memorabilia.
It's all emblematic of the continued troubles plaguing the Holy See's financial system, rocked by allegations of incompetence and corruption. But the new president of the Vatican bank, while acknowledging the delays and losses stemming from the credit card shutdown, is brushing off the fiasco.
"So sales will be up in the second half of the year," Ernst von Freyberg told the AP in an interview, laughing.
The truth is, however, that the credit card woes represent yet another headache for the Vatican as it works to improve its reputation internationally through a painful transition to financial transparency in the fight against money laundering.
In an interview this week, von Freyberg revealed that he was weighing whether to introduce some sort of tax reporting obligations on the bank ? known as the Institute for Religious Works ? to stem accusations that it's a tax haven.
"It may well be that having done a thorough legal review," von Freyberg said, "I come to the conclusion that we should pay more proactive attention to it."
The credit card debacle began Jan. 1 when Italy's central bank compelled Deutsche Bank Italia to stop providing electronic payment services to the Holy See. The Bank of Italy cited the lack of an EU-required banking regulatory framework in Vatican City.
The shutdown meant visitors to the Vatican Museums had to use cash to pay for tickets, audio guides and coffee table books on Michelangelo. It was a costly inconvenience given that museum revenues are the top money-maker for the Vatican, bringing in euro 91.3 million in 2011. The Vatican's other money-making initiatives were similarly affected: Its supermarket, pharmacy and duty-free department store were cash-only. So was its Philatelic and Numismatic Office, which issues commemorative and circulating stamps and coins for collectors and tourists alike.
"A disaster. A disaster. A disaster!" lamented Mauro Olivieri, the head of the coin and stamp office, which in 2012 was the Vatican's third-place money-maker with some euro 20 million in revenues. "The year 2013 has been what I call the 'annus horribilis.'"
The first half of 2013 should have been a windfall for Olivieri, given the world's attention was fixed on the Vatican for a solid month, from Benedict XVI's historic Feb. 11 announcement that he would retire at the end of the month, to the March 13 election of the first Jesuit pope and first pontiff from the Americas, Francis.
Such historic occasions are sought-after by coin and stamp collectors, who lined up in droves at temporary sales points in St. Peter's Square to buy the commemorative "Sede Vacante" stamps that were issued as soon as Benedict retired Feb. 28.
"Linn's Stamp News," the largest U.S. weekly on stamp news and the market, featured the four-stamp "Sede Vacante" collection on the front page of its March 18 editions.
But anyone who placed an order through the Vatican to buy the stamps electronically received word that credit card systems were down and orders couldn't be processed, even though the Vatican had announced two weeks earlier that the shutdown had been resolved.
So the order forms, thousands of them, piled up in boxes in Olivieri's offices.
Finally, on May 27 ? five months after the shutdown ? credit card sales resumed for stamps and coins, but the damage was done. The office is months behind schedule, with a backlog dating to November.
Overseas collectors who have long put up with the Vatican's antiquated way of handling orders ? through a time-consuming and labor-intensive subscription and order process rather than simple e-commerce ? said it was almost the final straw.
"They don't seem to run it like a business," said Henry Gitner, the main U.S. stamp dealer and retailer who years ago stopped buying directly from the Vatican because of the difficulties he encountered. "The only way to get guaranteed delivery ... is to literally have someone there buy it and ship it, and then you're paying a 10-15 percent commission."
In the U.S. alone, stamp collecting is a $1 billion a year industry, according to Linn's. Gitner estimated that a complete set of Vatican-issued stamps could run to around $8,000.
Olivieri said he had no idea how much had been lost, saying only that "undoubtedly" there were losses. Asked if the losses could reach millions, he said he couldn't say and that he had simply informed his superiors that 40 percent to 50 percent of his revenue comes from credit card sales.
"The Vatican had an enormous problem because this happened to the entire Vatican, not just to us: Think about the January sales at the duty-free store: a block on credit cards during the January sales? People coming here during sales with euro 600,000-700,000 in cash? Who comes with that? They come with credit cards."
The Vatican had announced Feb. 12 that Swiss firm Aduno Group had restarted credit card services in the Vatican. But only on-site "point of sales" terminals restarted then. E-commerce was something else entirely and it took until the end of May for the Vatican to adjust its web interfaces with Aduno's virtual terminals, said Karin Broder, an Aduno spokeswoman.
While visitors to the Vatican Museums can now buy their tickets online to avoid the lengthy lines, the e-commerce bookshop is still down, according to the museum website. Customers are asked to email requests instead.
Requests for comment from the Vatican Museums were not answered.
When asked why the Vatican didn't find a solution earlier, von Freyberg said simply "I hope that the next time we will not be caught like this. If you find yourself in such a situation, it certainly has a long story before it."
Von Freyberg said the aim now is to mend relations with the Bank of Italy and move forward on the Vatican's path of transparency.
"I'm very confident that I'll get it done," he said in an interview in his large office inside the Vatican bank. "And let's talk again ... and then either you have a human disaster story or I can offer you a glass of spumante (sparkling wine)."
For his part, Francis ? who has made clear he wants a church "of the poor and for the poor" ? this week gave another clue to his thoughts on finance.
"St. Peter didn't have a bank account," he said in a homily.
___
Follow Nicole Winfield at www.twitter.com/nwinfield
SAN FRANCISCO (AP) ? Apple is throwing out most of the real-world graphical cues from its iPhone and iPad software, like the casino-green "felt" of its Game Center app, in what it calls the biggest update since the iPhone's launch in 2007.
The new operating system, called iOS 7, strives for a clean, simple, translucent impression. Apple is redesigning all its applications and icons to conform to the new look, driven by long-time hardware design chief Jony Ive.
Apple demonstrated the new software at the Worldwide Developers Conference in San Francisco on Monday. The new design direction was widely expected and will show up on iPhones, iPad and iPod Touches this fall, the company said.
The software uses simple graphical elements in neon and pastel colors. Gone is the effort to make the icons looks like three-dimensional, embossed objects. Interface designers call the new guiding principle "flat," but on the iPhone's main screen, the background image will move subtly with the movement of the device, creating an illusion of depth. Other screens include plenty of white space.
The software has "a whole new structure that is coherent and is applied across the entire system," Ive said in a recorded presentation. "The design recedes, and in doing so, elevates your content."
While design modifications could help Apple distinguish its devices from rival phones and tablets, the company risks alienating longtime users.
Raluca Budiu, a senior researcher specializing in usability at the Nielsen Norman Group, said the so-called "flat" design can confuse users, because it can offer fewer signals about where to tap or click. That's been the case, she said, with Windows 8, which has a very "flat" design. Budiu said it's too early to say if it will be an issue with iOS.
Budiu noted that iOS users seem quite happy with the current iOS, which is easier to use than Google Inc.'s Android, its only big competitor.
Apple made a rare, major stumble with last year's iOS update, when it replaced Google's Maps application with its own navigation app. The underlying data for Apple's Maps was spottier and less accurate than Google's, users found. The Maps fracas didn't diminish the demand for iPhones, however.
Microsoft radical makeover of the Windows operating system in October provides a stronger example of the dangers of software revamps. Windows 8 was meant to give the company a stronger presence on tablet computers, but it ended up confusing many people who had become accustomed to using the old operating system on traditional desktops and laptops. Research firm IDC blamed Windows 8 for accelerating a decline in PC sales.
Among other changes, Apple's new iOS system will update apps automatically. It will store Web passwords online in Apple's syncing service, iCloud, making them available across devices. The AirDrop feature will allow sharing of big files with Apple-equipped people in the same room.
Apple took a jab at its rival, Samsung Electronics Co., which had been touting its Galaxy phones as better than iPhones because they sport near-field communication chips that allow people to share files by bumping phones together.
"No need to wander around the room bumping your phone with others," said Craig Federighi, senior vice president for software engineering.
The company also stepped up its rivalry with Google, maker of the Android software on Samsung and other phones. Apple said the Siri virtual assistant will use searches from Microsoft's Bing, Google's rival. Apple also is bringing its mapping service to desktops and laptops to compete with Google Maps and others.
The Cupertino, Calif., company is also launching a Pandora-like Internet radio service, iTunes Radio. It will be built into the Music app and stream music for free. There will be advertising, except for people who pay $25 a year for the iTunes Match online music storage.
Apple was a pioneer of online music sales and is still a leader in that field, but streaming services such as Pandora and Spotify have emerged as popular alternatives to buying. Pandora relies on its users being connected to the Internet at all times and plays songs at random within certain genres for free.
Last month, rival Google Inc. started an on-demand subscription music service called All Access that gives subscribers the ability to pick and choose specific songs and albums from a catalog of millions for playback on computers, tablets and smartphones in exchange for a monthly fee.
Apple updates its iOS operating system every year and doesn't charge for the updates. The new operating system will be available for the iPhone 4 and later models, and on the iPad 2 and later models, including the Mini. The launch of the new software traditionally coincides roughly with the launch of the year's new iPhone model.
Also at the conference, which runs through Friday, Apple revealed that it's switching from its more than decade-long practice of naming its Mac operating system updates after big cats. Instead, it's paying homage to the geography of its home state. Federighi says the next version of Mac OS X will be called Mavericks, after an undersea rock formation that produces big waves near Half Moon Bay, Calif.
The new operating system will extend battery life and shorten boot-up times, Federighi told the audience of software developers. The system improves support for multiple displays and imports the tab concept from Web browsers to the Finder file-organizer.
The software update will include iBooks for the first time, giving people who buy e-books from Apple a way to display them on the computer screen in addition to the iPhone and iPad. Competing e-book vendors such as Amazon and Barnes & Noble have cross-platform applications already.
There have been nine OS X versions named after big cats. The latest was Mountain Lion, released last year.
"We do not want to be the first software release in history to be delayed by a lack of cats," Federighi joked.
He said the new software will be out in the fall.
Apple also revealed a complete revamp of the Mac Pro, the boxy desktop model that's the work horse of graphics and film professionals. The new model is a black cylinder, one eighth the volume of the old box.
The current Mac Pro is the only Mac with internal hardware that can easily be modified and expanded by the user, but that possibility disappears with the new model. The company is adopting the same compact, one-piece design present in the Mac Mini and iMac.
The new Mac Pro will be the first Mac to be assembled in the U.S. in many years. CEO Tim Cook promised last year that the company would start a production line in the U.S., but didn't say where. Apple said the new computer will launch later this year.
2-D electronics take a step forwardPublic release date: 10-Jun-2013 [ | E-mail | Share ]
Contact: Mike Williams mikewilliams@rice.edu 713-348-6728 Rice University
Rice, Oak Ridge labs make semiconducting films for atom-thick circuits
HOUSTON (June 10, 2013) Scientists at Rice University and Oak Ridge National Laboratory (ORNL) have advanced on the goal of two-dimensional electronics with a method to control the growth of uniform atomic layers of molybdenum disulfide (MDS).
MDS, a semiconductor, is one of a trilogy of materials needed to make functioning 2-D electronic components. They may someday be the basis for the manufacture of devices so small they would be invisible to the naked eye.
The work appears online this week in Nature Materials.
The Rice labs of lead investigator Jun Lou, Pulickel Ajayan and Boris Yakobson, all professors in the university's Mechanical Engineering and Materials Science Department, collaborated with Wigner Fellow Wu Zhou and staff scientist Juan-Carlos Idrobo at ORNL in an unusual initiative that incorporated experimental and theoretical work.
The goals were to see if large, high-quality, atomically thin MDS sheets could be grown in a chemical vapor deposition (CVD) furnace and to analyze their characteristics. The hope is that MDS could be joined with graphene, which has no band gap, and hexagonal boron nitride (hBN), an insulator, to form field-effect transistors, integrated logic circuits, photodetectors and flexible optoelectronics.
"For truly atomic circuitry, this is important," Lou said. "If we get this material to work, then we will have a set of materials to play with for complete, complicated devices."
Last year, Lou and Ajayan revealed their success at making intricate patterns of intertwining graphene and hBN, among them the image of Rice's owl mascot. But there was still a piece missing for the materials to be full partners in advanced electronic applications. By then, the researchers were already well into their study of MDS as a semiconducting solution.
"Two-dimensional materials have taken off," Ajayan said. "The study of graphene prompted research into a lot of 2-D materials; molybdenum disulfide is just one of them. Essentially, we are trying to span the whole range of band gaps between graphene, which is a semimetal, and the boron nitride insulator."
MDS is distinct from graphene and hBN because it isn't exactly flat. Graphene and hBN are flat, with arrays of hexagons formed by their constituent atoms. But while MDS looks hexagonal when viewed from above, it is actually a stack, with a layer of molybdenum atoms between two layers of sulfur atoms.
Co-author Zheng Liu, a joint research scientist in Lou's and Ajayan's labs, noted the Yakobson group predicted that MDS and carbon atoms would bind. "We're working on it," he said. "We would like to stick graphene and MDS together (with hBN) into what would be a novel, 2-D semiconductor component."
"The question now is how to bring all the 2-D materials together," said co-author Sina Najmaei, a Rice graduate student. "They're very different species and they're being grown in very different environments."
Until recently, growing MDS in a usable form has been difficult. The "Scotch tape" method of pulling layers from a bulk sample has been tried, but the resulting materials were inconsistent, Lou said. Early CVD experiments produced MDS with grains that were too tiny to be of use for their electrical properties.
But in the process, the researchers noticed "islands" of MDS tended to form in the furnace where defects or even pieces of dust appeared on the substrate. "The material is difficult to nucleate, unlike hBN or graphene," Najmaei said. "We started learning that we could control that nucleation by adding artificial edges to the substrate, and now it's growing a lot better between these structures."
"Now we can grow grain sizes as large as 100 microns," Lou said. That's still only about the width of a human hair, but in the nanoscale realm, it's big enough to work with, he said.
Once the Ajayan and Lou teams were able to grow such large MDS arrays, the ORNL team imaged the atomic structures using aberration-corrected scanning transmission electron microscopy. The atomic array can clearly be seen in the images and, more importantly, so can the defects that alter the material's electronic properties.
"In order to improve the properties of 2-D materials, it's important to first understand how they're put together at a fundamental scale," Idrobo said. "Our microscopy facility at ORNL allows us to see materials in a way they've never been seen before -- down to the level of individual atoms."
Yakobson, a theoretical physicist, and his team specialize in analyzing the interplay of energy at the atomic scale. With ORNL's images in hand, they were not only able to calculate the energies of a much more complex set of defects than are found in graphene or BN but could also match their numbers to the images.
Among the Yakobson team's interesting finds was the existence, reported last year, of conductive subnano "wires" along grain boundaries in MDS. According to their calculations, the effect only occurred when grains met at precise 60-degree angles. The ORNL electron microscopy images make it possible to view these grain boundaries directly.
The Rice researchers see many possible ways to combine the materials, not only in two-dimensional layers but also as three-dimensional stacks. "Natural crystals are made of structures bound by the van der Waals force, but they're all of the same composition," Lou said. "Now we have the opportunity to build 3-D crystals with different compositions."
"These are very different materials, with different electronic properties and band gaps. Putting one on top of the other would give us a new type of material that we call van der Waals solids," Ajayan said. "We could put them together in whatever stacking order we need, which would be an interesting new approach in materials science.
###
Co-authors of the Nature Materials paper are Rice research associate Xiaolong Zou, graduate students Gang Shi and Sidong Lei, and Wu Zhou at Oak Ridge National Laboratory.
The Welch Foundation, the National Science Foundation (NSF), the U.S. Army Research Office, the U.S. Office of Naval Research, the Nanoelectronics Research Corporation and the Department of Energy supported the work.
Lou is an associate professor of mechanical engineering and materials science. Ajayan is the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of mechanical engineering and materials science, chemistry and chemical and biomolecular engineering. Yakobson is the Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and a professor of chemistry.
Computations were performed on Rice's DAVinCI system and at the Cyberinfrastructure for Computational Research, both funded by NSF.
Read the abstract at: http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat3673.html
This news release can be found online at http://news.rice.edu/2013/06/10/2-d-electronics-take-a-step-forward/
Follow Rice News and Media Relations via Twitter @RiceUNews
Related Materials:
Artificially Stacked Atomic Layers: Toward New van der Waals Solids: http://pubs.acs.org/doi/abs/10.1021/nl301061b
Intrinsic Structural Defects in Monolayer Molybdenum Disulfide: http://pubs.acs.org/doi/abs/10.1021/nl4007479
N3L Research Group (Jun Lou): http://mems.rice.edu/~jlou/
Schematics and experimental images produced by Oak Ridge National Laboratory show defects at the 60-degree grain boundaries in two-dimensional samples of molybdenum disulfide. The defects are 5- and 7-atom dislocation cores; the numbers refer to locations where the atomic arrangements veer from regular six-atom hexagons. Their presence indicates a one-dimensional conductive "wire" that runs along the boundary. In the illustration, the molybdenum atoms are cyan and the sulfur atoms are orange and yellow. (Credit: Oak Ridge National Laboratory)
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2-D electronics take a step forwardPublic release date: 10-Jun-2013 [ | E-mail | Share ]
Contact: Mike Williams mikewilliams@rice.edu 713-348-6728 Rice University
Rice, Oak Ridge labs make semiconducting films for atom-thick circuits
HOUSTON (June 10, 2013) Scientists at Rice University and Oak Ridge National Laboratory (ORNL) have advanced on the goal of two-dimensional electronics with a method to control the growth of uniform atomic layers of molybdenum disulfide (MDS).
MDS, a semiconductor, is one of a trilogy of materials needed to make functioning 2-D electronic components. They may someday be the basis for the manufacture of devices so small they would be invisible to the naked eye.
The work appears online this week in Nature Materials.
The Rice labs of lead investigator Jun Lou, Pulickel Ajayan and Boris Yakobson, all professors in the university's Mechanical Engineering and Materials Science Department, collaborated with Wigner Fellow Wu Zhou and staff scientist Juan-Carlos Idrobo at ORNL in an unusual initiative that incorporated experimental and theoretical work.
The goals were to see if large, high-quality, atomically thin MDS sheets could be grown in a chemical vapor deposition (CVD) furnace and to analyze their characteristics. The hope is that MDS could be joined with graphene, which has no band gap, and hexagonal boron nitride (hBN), an insulator, to form field-effect transistors, integrated logic circuits, photodetectors and flexible optoelectronics.
"For truly atomic circuitry, this is important," Lou said. "If we get this material to work, then we will have a set of materials to play with for complete, complicated devices."
Last year, Lou and Ajayan revealed their success at making intricate patterns of intertwining graphene and hBN, among them the image of Rice's owl mascot. But there was still a piece missing for the materials to be full partners in advanced electronic applications. By then, the researchers were already well into their study of MDS as a semiconducting solution.
"Two-dimensional materials have taken off," Ajayan said. "The study of graphene prompted research into a lot of 2-D materials; molybdenum disulfide is just one of them. Essentially, we are trying to span the whole range of band gaps between graphene, which is a semimetal, and the boron nitride insulator."
MDS is distinct from graphene and hBN because it isn't exactly flat. Graphene and hBN are flat, with arrays of hexagons formed by their constituent atoms. But while MDS looks hexagonal when viewed from above, it is actually a stack, with a layer of molybdenum atoms between two layers of sulfur atoms.
Co-author Zheng Liu, a joint research scientist in Lou's and Ajayan's labs, noted the Yakobson group predicted that MDS and carbon atoms would bind. "We're working on it," he said. "We would like to stick graphene and MDS together (with hBN) into what would be a novel, 2-D semiconductor component."
"The question now is how to bring all the 2-D materials together," said co-author Sina Najmaei, a Rice graduate student. "They're very different species and they're being grown in very different environments."
Until recently, growing MDS in a usable form has been difficult. The "Scotch tape" method of pulling layers from a bulk sample has been tried, but the resulting materials were inconsistent, Lou said. Early CVD experiments produced MDS with grains that were too tiny to be of use for their electrical properties.
But in the process, the researchers noticed "islands" of MDS tended to form in the furnace where defects or even pieces of dust appeared on the substrate. "The material is difficult to nucleate, unlike hBN or graphene," Najmaei said. "We started learning that we could control that nucleation by adding artificial edges to the substrate, and now it's growing a lot better between these structures."
"Now we can grow grain sizes as large as 100 microns," Lou said. That's still only about the width of a human hair, but in the nanoscale realm, it's big enough to work with, he said.
Once the Ajayan and Lou teams were able to grow such large MDS arrays, the ORNL team imaged the atomic structures using aberration-corrected scanning transmission electron microscopy. The atomic array can clearly be seen in the images and, more importantly, so can the defects that alter the material's electronic properties.
"In order to improve the properties of 2-D materials, it's important to first understand how they're put together at a fundamental scale," Idrobo said. "Our microscopy facility at ORNL allows us to see materials in a way they've never been seen before -- down to the level of individual atoms."
Yakobson, a theoretical physicist, and his team specialize in analyzing the interplay of energy at the atomic scale. With ORNL's images in hand, they were not only able to calculate the energies of a much more complex set of defects than are found in graphene or BN but could also match their numbers to the images.
Among the Yakobson team's interesting finds was the existence, reported last year, of conductive subnano "wires" along grain boundaries in MDS. According to their calculations, the effect only occurred when grains met at precise 60-degree angles. The ORNL electron microscopy images make it possible to view these grain boundaries directly.
The Rice researchers see many possible ways to combine the materials, not only in two-dimensional layers but also as three-dimensional stacks. "Natural crystals are made of structures bound by the van der Waals force, but they're all of the same composition," Lou said. "Now we have the opportunity to build 3-D crystals with different compositions."
"These are very different materials, with different electronic properties and band gaps. Putting one on top of the other would give us a new type of material that we call van der Waals solids," Ajayan said. "We could put them together in whatever stacking order we need, which would be an interesting new approach in materials science.
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Co-authors of the Nature Materials paper are Rice research associate Xiaolong Zou, graduate students Gang Shi and Sidong Lei, and Wu Zhou at Oak Ridge National Laboratory.
The Welch Foundation, the National Science Foundation (NSF), the U.S. Army Research Office, the U.S. Office of Naval Research, the Nanoelectronics Research Corporation and the Department of Energy supported the work.
Lou is an associate professor of mechanical engineering and materials science. Ajayan is the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of mechanical engineering and materials science, chemistry and chemical and biomolecular engineering. Yakobson is the Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and a professor of chemistry.
Computations were performed on Rice's DAVinCI system and at the Cyberinfrastructure for Computational Research, both funded by NSF.
Read the abstract at: http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat3673.html
This news release can be found online at http://news.rice.edu/2013/06/10/2-d-electronics-take-a-step-forward/
Follow Rice News and Media Relations via Twitter @RiceUNews
Related Materials:
Artificially Stacked Atomic Layers: Toward New van der Waals Solids: http://pubs.acs.org/doi/abs/10.1021/nl301061b
Intrinsic Structural Defects in Monolayer Molybdenum Disulfide: http://pubs.acs.org/doi/abs/10.1021/nl4007479
N3L Research Group (Jun Lou): http://mems.rice.edu/~jlou/
Schematics and experimental images produced by Oak Ridge National Laboratory show defects at the 60-degree grain boundaries in two-dimensional samples of molybdenum disulfide. The defects are 5- and 7-atom dislocation cores; the numbers refer to locations where the atomic arrangements veer from regular six-atom hexagons. Their presence indicates a one-dimensional conductive "wire" that runs along the boundary. In the illustration, the molybdenum atoms are cyan and the sulfur atoms are orange and yellow. (Credit: Oak Ridge National Laboratory)
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Public release date: 10-Jun-2013
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