Researchers are reporting key milestones in developing new semiconductors to potentially replace silicon in future computer chips and for applications in flexible electronics. Findings are detailed in three technical papers, including one focusing on a collaboration of researchers from Purdue Univ., Intel Corp. and SEMATECH. The team has demonstrated the potential promise of a 2-D semiconductor called molybdenum disulfide.
Investigated heavily since the 1970s, solar cells have been the great unfulfilled promise for unlimited, almost free energy to power the world. The reasoning is solid: The Earth absorbs almost as much energy per hour than the entire human race uses in a single year.
The basic element of modern electronics, namely the transistor, suffers from significant current leakage. By enveloping a transistor with a shell of piezoelectric material, which distorts when voltage is applied, researchers in the Netherlands were able to reduce this leakage by a factor of five compared to a transistor without this material.
Research published in the Proceedings of the National Academy of Sciences makes it possible to predict how subjecting metals to severe pressure can lower their electrical resistance, a finding that could have applications in computer chips and other materials that could benefit from specific electrical resistance.
A team at Lawrence Berkeley National Laboratory found unexpected traces of water in semiconducting nanocrystals. The water as a source of small ions for the surface of colloidal lead sulfide nanoparticles allowed the team to explain just how the surface of these important particles are passivated, meaning how they achieve an overall balance of positive and negative ions.
Researchers are trying to develop solar-driven generators that can split water, yielding hydrogen gas that could be used as clean fuel. Such a device requires efficient light-absorbing materials that attract and hold sunlight to drive the chemical reactions involved in water splitting. Semiconductors are excellent light absorbers. However, these materials rust when submerged in the type of water solutions found in such systems.
In recent work at Brookhaven National Laboratory, semiconductor quantum dots (QDs) have been combined with graphene to develop nanoscale photonic devices that can dramatically improve our ability to detect light. The research has demonstrated that the thickness of the organic molecule layer that typically surrounds the QDs is crucial in attaining sufficiently high efficiency of light/energy transfer into the graphene.
Researchers have found that a particular species of quantum dots that weren't commonly thought to blink, do. So what? Well, although the blinks are short, even brief fluctuations can result in efficiency losses that could cause trouble for using quantum dots to generate photons that move information around inside a quantum computer or between nodes of a future high-security internet based on quantum telecommunications.
Inspired by fictional cyborgs like Terminator, a team of researchers at the Univ. of Michigan and the Univ. of Pittsburgh has made the first bionic particles from semiconductors and proteins. These particles recreate the heart of the process that allows plants to turn sunlight into fuel.
Modern supercapacitors store ten times less energy than a lithium-ion battery but can last a thousand times longer. The main drawback of supercapacitors, however, is the inability to cope with stresses such as pressure and vibration. Researchers have developed a new supercapacitor that operates flawlessly in storing and releasing electrical charge while subject to stresses or pressures up to 44 psi and vibrational accelerations over 80 g.
Using a material found in Silly Putty and surgical tubing, a group of researchers at the Univ. of California, Riverside Bourns College of Engineering have developed a new way to make lithium-ion batteries that will last three times longer between charges compared to the current industry standard. The innovation involves the development of silicon dioxide nanotube anodes.
A new approach to integrated circuits, combining atoms of semiconductor materials into nanowires and structures on top of silicon surfaces, shows promise for a new generation of fast, robust electronic and photonic devices. Engineers in California have recently demonstrated 3-D nanowire transistors using this approach that open exciting opportunities for integrating other semiconductors, such as gallium nitride, on silicon substrates.
A research team that figured out how to coat an organic material as a thin film wanted a closer look at why their spreadable organic semiconductor grew like it did. So Cornell Univ. scientists used their high-energy synchrotron x-ray source to show how these organic molecules formed crystal lattices at the nanoscale. These high-speed movies could help advance the technology move from the laboratory to mass production.
First proposed for memory in the 1970s, phase-change materials exhibit two metastable states which can store data when placed between two electrically conducting electrodes. IBM researchers in Zurich have recently used them as part of Project Theseus to develop a PCI-e card that melds flash memory with phase-change memory. The major improvement in speed interests IBM for Big Data applications.
Current approaches to flexible electronics, in which very thin semiconductor materials are applied to a thin, flexible substrate in wavy patterns and then applied to a deformable surface such as skin or fabric, are still built around hard composite materials that limit their elasticity. Researchers in California have made several discoveries, however, that could lead to electronics that are "molecularly stretchable."
The icing on the cake for semiconductor nanocrystals that provide a non-damped optoelectronic effect may exist as a layer of tin that segregates near the surface. One method of altering the electrical properties of a semiconductor is by introducing impurities called dopants. A team of researchers has demonstrated that equally important as the amount of dopant is how the dopant is distributed on the surface and throughout the material.
The drive to develop ultra-small and ultra-fast electronic devices using a single atomic layer of semiconductors, such as transition metal dichalcogenides, has received a significant boost. Researchers with Lawrence Berkeley National Laboratory have recorded the first observations of a strong nonlinear optical resonance along the edges of a single layer of molybdenum disulfide.
Researchers around the world have been working to harness the unusual properties of graphene, a 2-D sheet of carbon atoms. But graphene lacks one important characteristic that would make it even more useful: a property called a bandgap, which is essential for making devices such as computer chips and solar cells.
Molybdenite has been instrumental in research at the Federal Institute of Technology in Switzerland (EPFL), where scientists have used it to develop a computer chip, flash memory device and a photographic sensor. Now, they have again tapped into the electronic potential of MoS2 by creating diodes that can emit light or absorb it to produce electricity.
Although it is relatively cheap and easy to encode information in light for fiber optic transmission, storing information is most efficiently done using magnetism, which ensures information will survive for years without any additional power. But a new proposal by researchers would replace silicon used in these devices with plastic. Their solution converts magnetic information to light in a flexible plastic device.
One of the great problems in physics is the detection of electromagnetic radiation—that is, light—which lies outside the small range of wavelengths that the human eye can see. Think x-rays, for example, or radio waves. Now, researchers have discovered a way to use existing semiconductors to detect a far wider range of light than is now possible, well into the infrared range.
Nanoengineering researchers at Rice Univ. and Nanyang Technological Univ. in Singapore have unveiled a potentially scalable method for making one-atom-thick layers of molybdenum diselenide—a highly sought semiconductor that is similar to graphene but has better properties for making certain electronic devices like switchable transistors and light-emitting diodes.
Germanium monosulfide (GeS) is emerging as one of the most important class "IV–VI" semiconductor materials with potential in optoelectronics applications for telecommunications and computing. Adding a new element of control to preparation of this material, researchers in China have found a convenient way to selectively prepare GeS nanostructures, including nanosheets and nanowires, that are more active than their bulk counterparts
Interest in oxide-based semiconductor electronics has exploded in recent years, fueled largely by the ability to grow atomically precise layers of various oxide materials. One of the most important materials in this burgeoning field is strontium titanate, a nominally nonmagnetic wide-bandgap semiconductor, and researchers have found a way to magnetize this material using light, an effect that persists for hours at a time.
Until now, it has been hard to couple light generation into layered semiconductor systems. Scientists in Austria have recently solved this problem using metamaterials, which are able to manipulate light in the terahertz range due to their special microscopic structure. This represents the first combination of metamaterials and quantum cascade structures.