Transistors Made Of 2-D Materials - C&EN Global Enterprise (ACS

May 12, 2014 - “Flexible and transparent transistors are important for future flexible smart devices,” he says. In two new studies, the research t...
2 downloads 3 Views 395KB Size
NEWS OF TH E WEEK

PFIZER CHASES MERGER DEAL

PFIZER PROMISES TO … ◾ Establish corporate and tax residence in England ◾ Locate European business and regulatory headquarters in the U.K. ◾ Employ 20% or more of its eventual R&D workforce in the U.K.

◾ Put key scientific leadership in place in the U.K. ◾ Complete AstraZeneca R&D campus in Cambridge, England ◾ Maintain manufacturing in Macclesfield, England

Technology committees, respectively, will hear from the companies, trade unions, and government officials about the potential impact of what could be the largest foreign takeover of a U.K. firm. The hearing will be “an opportunity to scrutinize the pledges on research and development being made” and “pose questions about how the government will ensure that these commitments are met,” according to Science Committee Chair Andrew Miller. Well-known for postacquisition job cutting, Pfizer eliminated 2,000 positions when it closed its Sandwich, England, site in 2011. AstraZeneca accounts for about 2.5% of exports and employs 7,000 people in the U.K. “The life sciences industry is of paramount importance to the U.K. as part of the government’s industrial strategy,” Secretary of State for Business, Innovation & Skills Vince Cable told the House of Commons on May 6. “We are committed to ensuring that we are at the forefront of life sciences research and development, with high-quality jobs, manufacturing, and decision making in the U.K.” Although a merger decision is “ultimately a matter for the shareholders of both companies,” Cable suggested that the government might be able to use its powers, if not blocked by the European Commission, to assess if the deal is in the public interest. Doing so would be “a serious step, and not one that should be taken lightly,” he added.—ANN THAYER

ACQUISITIONS: Drug firm pursues AstraZeneca despite rejections and U.K. concerns FIZER IS STILL pushing to create a tax-advan-

P

taged U.K.-based drug giant even after AstraZeneca rejected its latest $106 billion takeover offer. To bolster Pfizer’s position, CEO Ian C. Read has promised British Prime Minister David Cameron that the company will keep significant operations in the U.K. The company also is highlighting the benefits of a merger in a new infographic on its merger-related website. AstraZeneca is countering by making its case for independence. In a call with analysts last week, CEO Pascal Soriot emphasized that the firm “now has the right size, focus, and team to deliver on one of the most exciting pipelines in the pharmaceutical industry.” AstraZeneca, like Pfizer, has been struggling with declining sales. Both Read and Soriot will have to provide even more answers. At meetings on May 13 and 14, the U.K. Parliament’s Business, Innovation & Skills and Science &

TRANSISTORS MADE OF 2-D MATERIALS ELECTRONICS: The fast, ultrathin

devices could enable sharp, low-power flexible displays

WO INDEPENDENT RESEARCH groups report

T

the first transistors built entirely of two-dimensional electronic materials, making the devices some of the thinnest yet. The transistors, just a few atoms thick and hence transparent, could lead to bright, bendable, high-resolution displays. Both groups’ devices signal important progress, says Deji Akinwande, an electrical engineer at the University of Texas, Austin, who was not involved in either study. “Flexible and transparent transistors are important for future flexible smart devices,” he says. In two new studies, the research teams, one at Argonne National Laboratory and the other at the University of California, Berkeley, used 2-D materials to make all three components of a transistor: a semiconductor, a set of electrodes, and CEN.ACS.ORG

6

ACS NANO

Built on a silicon wafer, an ultrathin transistor made with 2-D materials uses graphene for electrodes, molybdenum disulfide as its semiconductor layer, and boron nitride as an insulator.

an insulating layer to keep the other two parts separated in some areas. Such all-2-D transistors are smaller than their silicon-based counterparts and would allow for a super-high density of pixels in next-generation displays. Saptarshi Das, Anirudha V. Sumant, and their colleagues at Argonne made flexible transistors using graphene for the electrodes, tungsten diselenide (WSe2) for the semiconductor, and hexagonal boron nitride as the insulator (Nano Lett. 2014, DOI: 10.1021/ nl5009037). Electrons travel in the devices about 100 times faster than in amorphous silicon devices used to drive today’s flat-panel displays. The transistors’ high electron mobility means the devices can switch faster. Switching speed dictates a display’s refresh rate and is necessary for high-quality video, especially 3-D video. The UC Berkeley group, led by electrical engineer Ali Javey, made similar transistors, except they used molybdenum disulfide (MoS2) as the semiconductor (ACS Nano 2014, DOI: 10.1021/nn501723y). Their transistors have an electron mobility about 70 times higher than that of amorphous silicon devices. All-2-D transistors have one major limitation, says Vitaly Podzorov, a physicist at Rutgers University: No good methods currently exist for making large-area films of WSe2 and MoS2. In both studies, the research teams exfoliated flakes of the materials from crystals using Scotch tape. Nevertheless, Podzorov says, these two proof-of-concept demonstrations show the promise of 2-D transistors.—PRACHI PATEL, special to C&EN

MAY 12, 2014