Science

Tags:

Layered '2-D nanocrystals' promising new semiconductor

The two-dimensional layered semiconducting di-chalcogenides are emerging as promising candidates for post-Si-CMOS applications owing to their excellent electrostatic integrity and the presence of a finite energy bandgap, unlike graphene. However, in order to unravel the ultimate potential of these materials, one needs to investigate different aspects of carrier transport. In this Letter, we present the first comprehensive experimental study on the dependence of carrier mobility on the layer thickness of back-gated multilayer MoS2 field-effect transistors. We observe a non-monotonic trend in the extracted effective field-effect mobility with layer thickness, which is of relevance for the design of high-performance devices. We also discuss a detailed theoretical model based on Thomas-Fermi charge screening and interlayer coupling in order to explain our experimental observations. Our model is generic and, therefore, is believed to be applicable to any two-dimensional layered system.

47266.jpg
Researchers are developing a new type of semiconductor technology, pictured here, for future computers and electronics based on "two-dimensional nanocrystals." The material is layered in sheets less than a nanometer thick that could replace today's silicon transistors.

Tags:

Chloroform cleanup: just the beginning for palladium-gold catalysts: Federally funded research pays off with new process for environmental remediation

Researchers from Rice University, DuPont Central Research and Development and Stanford University have announced a full-scale field test of an innovative process that gently but quickly destroys some of the world's most pervasive and problematic pollutants. The technology, called PGClear, originated from basic scientific research at Rice during a 10-year, federally funded initiative to use nanotechnology to clean the environment.

47267.jpg
When chloroform-contaminated water is flowed through a column containing PGClear pellets, the palladium and gold in the pellets spurs a chemical reaction that breaks down chloroform into nontoxic methane and chloride salt.

Tags:

Where are the Best Windows Into Europa's Interior?

pia16921-640_0.jpg
This graphic of Jupiter's moon Europa maps a relationship between the amount of energy deposited onto the moon from charged-particle bombardment and the chemical contents of ice deposits on the surface in five areas of the moon (labeled A through E).

Tags:

U.S. Naval Research Laboratory Scientists “See” Flux Rope Formation for the First Time

CME-rope-pic-425x379.jpg
Models of flux ropes have been drawn by theorists in the past, but scientists had never before observed them at the time they formed.

Tags:

Blame it on the Rain (from Saturn's Rings)

pia16842-640_0_0.jpg
This artist's concept illustrates how charged water particles flow into the Saturnian atmosphere from the planet's rings, causing a reduction in atmospheric brightness.

Tags:

W3 star-forming region

W3_Herschel_small_0.jpg
The full image of the W3 region. Click on the image to see an annotated version, highlighting some of the key features.

Tags:

Interdisciplinary team demonstrates superconducting qualities of topological insulators: Findings may prove useful in search for elusive Majorana quasiparticle

Topological insulators (TIs) are an exciting new type of material that on their surface carry electric current, but within their bulk, act as insulators. Since the discovery of TIs about a decade ago, their unique characteristics (which point to potential applications in quantum computing) have been explored theoretically, and in the last five years, experimentally.

47247.jpg
Top left: SEM image of a typical device. Mechanically exfoliated Bi2Se3 thin film is colored as brown and contact metals consist of Ti(2.5nm)/Al(140nm). Top right: Hall data where red curve is longitudinal resistivity and blue curve is Hall carrier density as a function of gate voltage. Bottom figure: 2D plot of differential resistance as a function of gate voltage(x axis) and current(y axis). Purple region in the center corresponds to zero differential resistance (superconducting regime)

Tags:

Deep Space Applauds NASA Asteroid Initiative - Calls for Collaboration with Private Sector

NASA's new project to retrieve and study a small asteroid represents an opportunity to do things a new way in space, says Deep Space Industries. NASA's asteroid plans, if coupled with private sector initiatives, will be a great start to understanding both the threat and promise of space objects - saving taxpayer funds while also helping kick start a new U.S.-led commercial space industry.

47251.jpg

Tags:

Suzaku 'Post-mortem' Yields Insight into Kepler's Supernova

740048main1_kepler-670_0_0.jpg
This composite of images from NASA's Chandra X-ray Observatory shows the remnant of Kepler's supernova in low (red), intermediate (green) and high-energy (blue) X-rays. The background is an optical star field taken from the Digitized Sky Survey. The distance to the object is uncertain, with estimates ranging from 13,000 to 23,000 light-years, but recent studies favor the maximum range. This image spans 12 arcminutes or about 80 light-years at the greatest distance.

Tags:

Hubble Breaks Record in Search for Farthest Supernova

739211main1_sn_wilson673_1_0.jpg
This is a Hubble Space Telescope view of supernova SN UDS10Wil, nicknamed SN Wilson that exploded over 10 billion years ago. The small box in the top image pinpoints SN Wilson's host galaxy in the CANDELS survey. The image is a blend of visible and near-infrared light. The three bottom images, taken in near-infrared light demonstrate how the astronomers found the supernova. The image at far left shows the host galaxy without SN Wilson. The middle image, taken a year earlier, reveals the galaxy with SN Wilson. The supernova cannot be seen because it is too close to the center of its host galaxy. To detect the supernova, astronomers subtracted the left image from the middle image to see the light from SN Wilson, shown in the image at far right.

Could not connect2