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.
Existing transistors act as electronic switches, altering current flow through a semiconductor by controlling the bias voltage across the channel region. A new electronic component, called a source-gated transistor, has been developed in the U.K. and exploits physical effects such as the Schottky barriers at metal-semiconductor contacts. This innovation could improve the reliability of future digital circuits used within flexible gadgets.
From super-lubricants, to solar cells, to the fledgling technology of valleytronics, there is much to be excited about with the discovery of a unique new 2-D semiconductor, rhenium disulfide, by researchers at Lawrence Berkeley National Laboratory’s Molecular Foundry. Rhenium disulfide, unlike molybdenum disulfide and other dichalcogenides, behaves electronically as if it were a 2-D monolayer even as a 3-D bulk material.
Researchers from North Carolina State Univ. have developed a new processing technique that makes light-emitting diodes (LEDs) brighter and more resilient by coating the semiconductor material gallium nitride (GaN) with a layer of phosphorus-derived acid.
Changing the texture and surface characteristics of a semiconductor material at the nanoscale can influence the way that neural cells grow on the material. The finding stems from a study performed by researchers at North Carolina State Univ., the Univ. of North Carolina at Chapel Hill and Purdue Univ., and may have utility for developing future neural implants.
Organic solar cells are a compelling thin-film photovoltaic technology in part because of their compatibility with flexible substrates and tunable absorption window. Belgium-based chipmaker imec has set a new conversion efficiency record of 8.4% for this type of cell by developing fullerene-free acceptor materials and a new multilayer semiconductor device structure.
A new study by Berkeley Lab researchers shows that nearly 90% of the electrons generated by a hybrid material designed to store solar energy in hydrogen are being stored in the target hydrogen molecules. Interfacing the semiconductor gallium phosphide with a cobaloxime catalyst provides an inexpensive photocathode for bionic leaves that produce energy-dense fuels from nothing more than sunlight, water and carbon dioxide.
Experts from the Univ. of Buffalo (UB), helped by colleagues from two Chinese universities, have developed an optical "nanocavity" that could help increase the amount of light absorbed by ultrathin semiconductors. The advancement could lead to the creation of more powerful photovoltaic cells and improvements in video cameras and even hydrogen fuel, as the technology could aid the splitting of water using energy from light.
Light-emitting diodes (LEDs) are durable and save energy. Now, researchers have found a way to make LED lamps even more compact while supplying more light than commercially available models. The key to this advance are a new type of transistors made of the semiconductor material gallium nitride.
In physics, there's small, and then there's nullity, as in zero-dimensional. Univ. of Cincinnati researchers have reached this threshold with a special structure, zero-dimensional quantum dots, that may someday lead to better ways of harnessing solar energy, stronger lasers or more sensitive medical diagnostic devices.
JILA physicists used an ultrafast laser and help from German theorists to discover a new semiconductor quasiparticle, a handful of smaller particles that briefly condense into a liquid-like droplet. Quasiparticles are composites of smaller particles that can be created inside solid materials and act together in a predictable way.
Associated with unhappy visits to the dentist, “cavity” means something else in the science of optics. An arrangement of mirrors that allows beams of light to circulate in closed paths, or cavities, help us build laser and optical fibers. Now, a research team pushed the concept further by developing an optical “nanocavity” that boosts the amount of light that ultrathin semiconductors absorb.
An undesired effect in thin film amorphous silicon solar cells has puzzled the scientific community for the last 40 years. This effect, known as light-induced degradation, is responsible for reducing solar cell efficiency over time. Researchers in Germany have recently demonstrated that tiny voids within the silicon network are partly responsible for 10 to 15% efficiency loss as soon as they are used.
European scientists from both academia and industry have begun an ambitious new research project focused on an alternative approach to extend Moore's Law. The research project, coordinated IBM Research in Zurich and called COMPOSE³, is based on the use of new materials to replace today's silicon, and on taking an innovative design approach where transistors are stacked vertically, known as 3-D stacking.
Researchers at Tyndall National Institute in Ireland have produced the first ever atom-by-atom simulation of nanoscale film growth by atomic layer deposition (ALD), a thin-film technology used in the production of silicon chips. The accomplishment required the acquisition of the complete set of hundreds of ALD reactions at the quantum mechanical level.
New research hints that nanodevices in microcircuits can protect themselves from heat generation through the transformation of nanotransistors into quantum states. The finding, demonstrated in nanoscale semiconductors devices, could boost computing power without large-scale changes to electronics.
Researchers have tried a variety of methods to develop detectors that are responsive to a broad range of infrared light, but these methods have all faced limitations. Now, a new system developed by researchers at five institutions could eliminate many of those limitations. The new system works at room temperature and provides a broad infrared response.
The goal of fabricating fixed-size one-dimensional silica structures and being able to precisely control the diameter during growth has long eluded scientists. Now, Oak Ridge National Laboratory researchers Panos Datskos and Jaswinder Sharma have demonstrated what they describe as the addressable local control of diameter of each segment of the silica rod.
There are examples of art imitating nature all around us, from Monet to Chihuly, but when physicist Latika Menon peered under the electron microscope last fall, she discovered the exact opposite in gallium nitride nanowires that bore an uncanny resemblance to artistic pots found in her native India. Menon has begun to control these shapes, which will make the nanowires significantly more promising for use in advanced devices.
By applying pressure to a semiconductor, researchers have been able to transform a semiconductor into a “topological insulator” (TI), an intriguing state of matter in which a material’s interior is insulating but its surfaces or edges are conducting with unique electrical properties. This is the first time that researchers have used pressure to gradually “tune” a material into the TI state.
Transistors, the workhorses of the electronics world, are plagued by leakage current. This results in unnecessary energy losses, which is why smartphones and laptops, for example, have to be recharged so often. Researchers have recently shown that this leakage current can be radically reduced by “squeezing” the transistor with a piezoelectric material. Using this approach, they have surpassed the theoretical limit for leakage current.