One of the major road blocks to the design and development of new, more efficient solar cells may have been cleared. Researchers with the Lawrence Berkeley National Laboratory have developed the first ab initio method for characterizing the properties of “hot carriers” in semiconductors. Hot carriers are electrical charge carriers with significantly higher energy than charge carriers at thermal equilibrium.
Researchers have taken a major stride toward perfectly efficient lighting that is also relatively inexpensive and simple to make. The same material can also reveal the presence of water by changing color. Incandescent bulbs only turn 5% of the electricity they use into light, while fluorescent LEDs can produce light from up to 25% of the electrons that pass through them. Phosphorescent LEDs can turn every electron into a ray of light.
First developed five years ago at Rice Univ., silicon oxide memories are a type of two-terminal, “resistive random-access memory” (RRAM) technology that beats flash memory’s data density by a factor of 50. At Rice, the laboratory of chemist and 2013 R&D Magazine Scientist of the Year James Tour has recently developed a new version of RRAM that Tour believes outperforms more than a dozen competing versions.
Researchers at Pacific Northwest National Laboratory have developed a porous material to replace the graphite traditionally used in a battery's electrodes. Made from silicon, which has more than 10 times the energy storage capacity of graphite, the sponge-like material can help lithium-ion batteries store more energy and run longer on a single charge.
Using graphene ribbons just several atoms across, a group of researchers at the Univ. of Wisconsin-Milwaukee has found a novel way to “tune” the material, causing the extremely efficient conductor of electricity to act as a semiconductor. By imaging the ribbons with scanning-tunneling microscopy, researchers have confirmed how narrow the ribbon width must be. Achieving less than 10 nm in width is a big challenge.
Experiments aimed at devising new types of photodetectors have been triggered by the increasing use of optoelectronic devices. Researchers in China have proposed a new type of infrared photodetector made from zinc oxide and silicon. Its nanoporous nature, synthesized by a simple sol-gel method, allows it to be responsive to infrared wavelengths.
In semiconductor-based components, high mobility of charge-carrying particles is important. In organic materials, however, it is uncertain to what degree the molecular order within the thin films affects the mobility and transport of charge carriers. Using a new imaging method, researchers have shown that thin-film organic semiconductors contain regions of structural disorder that could inhibit the transport of charge and limit efficiency.
Engineers at the Univ. of Arkansas have designed integrated circuits that can survive at temperatures greater than 350 C—or roughly 660 F. The team achieved the higher performance by combining silicon carbide with wide temperature design techniques. In the world of power electronics and integrated circuits, their work represents the first implementation of a number of fundamental analog, digital and mixed-signal blocks.
At the 2014 Symposium on VLSI Technology in Triangle Park, N.C., researchers from the Univ. of California, Santa Barbara introduced the highest-performing class III-V metal-oxide semiconductor field-effect transistors (MOSFETs) yet demonstrated. The new MOSFETs exhibit, in an industry first, on-current, off-current and operating voltage comparable to or exceeding production silicon devices, while also staying relatively compact.
Crystal IS has introduced Optan, the first commercial semiconductor based on native aluminum nitride (AIN) substrates. Optan increases detection sensitivity from monitoring of chemicals in pharma manufacturing to drinking water analysis.
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."