Many of today’s semiconductor technologies hinge upon the absorption of light. Absorption is critical for nano-sized structures at the interface between two energy barriers called quantum wells, in which the movement of charge carriers is confined to two dimensions. Working with the semiconductor indium arsenide, a team of researchers has discovered a quantum unit of photon absorption that should be general to all 2-D semiconductors.
From solar cells to opto-electronic sensors to lasers and imaging devices, many of today’s semiconductor technologies hinge upon the absorption of light. Absorption is especially critical for nano-sized structures at the interface between two energy barriers called quantum wells. Now, for the first time, a simple law of light absorption for 2-D semiconductors has been demonstrated.
A collaboration of scientists from the Univ. of Minnesota and the National Renewable Energy Laboratory have developed a new method to use an ionized gas, called nonthermal plasma, to produce silicon nanocrystals and cover their surfaces with a layer of chlorine atoms. This method allows production of stable silicon inks without organic ligand molecules and also greatly enhances conductivity.
Combining experiment and theory, Cornell Univ. researchers have shown that when grown in stacked layers, graphene produces some specific defects that influence its conductivity. Previously it was thought that when perfectly stacked in layers, graphene would be defect-free. Instead, it ripples. The finding could influence efforts to make graphene act like a semiconductor.
Andrew Greytak, a chemist at the University of South Carolina, is leading a research team that’s making the process of synthesizing quantum dots much more systematic. His group recently detailed an effective new method for purifying cadmium selenide nanocrystals with well-defined surface properties. The advance required the adoption of gel-permeation chromatography.
A team led by Rice University chemist James Tour has built a 1-kilobit rewritable device with diodes that eliminate data-corrupting crosstalk. This chip, which uses cheap, plentiful silicon oxide to store data, shows it should be possible to surpass the limitations of flash memory in packing density, energy consumption per bit and switching speed.
An unlikely material, cubic boron arsenide, could deliver an extraordinarily high thermal conductivity—on par with the industry standard set by costly diamond. The discovery that the chemical compound of boron and arsenic could rival diamond surprised the team of theoretical physicists. But a new theoretical approach allowed the team to unlock the secret to boron arsenide's potentially extraordinary ability to conduct heat.
In the constant push for smaller transistors, researchers have been investigating oxides with higher K, or dielectric constant, values. Materials such as germanium, hafnium, and titanium are being investigated for this role, but many prototypes leak electrons. At the National Synchrotron Light Source, x-rays are being used to probe the electronic behavior of a germanium-based transistor structure that could offer a solution.
Researchers in Switzerland have designed prototype for an image sensor based on the semiconducting properties of molybdenite. Their sensor only has a single pixel, but it needs five times less light to trigger a charge transfer than the silicon-based sensors that are currently available.
Through-focus scanning optical microscopy, a technique developed several years ago at NIST for improving optical microscopes, now has been applied to monitoring the next generation of computer chip circuit components, potentially providing the semiconductor industry with a crucial tool for improving chips for the next decade or more.
The world’s most advanced extreme-ultraviolet microscope is about to go online at Lawrence Berkeley National Laboratory, and the queue of semiconductor companies waiting to use it already stretches out the door. The much-anticipated SHARP microscope will provide semiconductor companies with the means to push their chip-making technology to new levels of miniaturization and complexity.
At the IEEE Photovoltaic Specialists Conference in Tampa, Fla. last week, National Renewable Energy Laboratory scientist Myles Steiner announced a world record of 31.1% conversion efficiency for a two-junction solar cell under one sun of illumination. The achievement edges the previous record of 30.8% by Alta Devices.
Silicon can accept ten times more lithium than the graphite used in the electrodes in lithium-ion batteries, but silicon also expands, shortening electrode life. Looking for an alternative to pure silicon, scientists in Germany have now synthesized a novel framework structure consisting of boron and silicon, which could serve as electrode material.
Researchers in Munich, Germany, have recently published work that describes experiments in which inexpensive semiconductor lasers have produced high-energy light pulses as short as 60 picoseconds without the drawbacks of previous approaches in terms of power consumption and device size. They say the new technique, based on the use of a new Fourier domain mode-locked laser, could open the door to subpicosecond pulses.
High-performance thermoelectric materials that convert waste heat to electricity could one day be a source of more sustainable power. But they need to be a lot more efficient before they could be effective on a broad scale in places like power plants or military bases, researchers say. A University of Michigan researcher has taken a step toward that goal.
Leaders of the National Science Foundation (NSF) and the Semiconductor Research Corporation (SRC), the world's leading university-research consortium for semiconductors and related technologies, this week announced 18 new projects funded through a joint initiative to address research challenges in the design of failure-resistant circuits and systems.
Researchers at North Carolina State University have developed a new technique for creating high-quality semiconductor thin films at the atomic scale—meaning the films are only one atom thick. The technique can be used to create these thin films on a large scale, sufficient to coat wafers that are two inches wide, or larger.
From the high-resolution glow of flat screen televisions to light bulbs that last for years, light-emitting diodes (LEDs) continue to transform technology. Their full potential, however, remains untapped. A contentious controversy surrounds the high intensity of indium gallium nitride, with experts split on whether or not indium-rich clusters within the material provide the LED's remarkable efficiency.
From powerful computers to super-sensitive medical and environmental detectors that are faster, smaller, and use less energy—yes, we want them, but how do we get them? In research that is helping to lay the groundwork for the electronics of the future, University of Delaware scientists have confirmed the presence of a magnetic field generated by electrons which scientists had theorized existed, but that had never been proven until now.
University of Utah metallurgists have used an old microwave oven to produce a nanocrystal semiconductor rapidly using cheap, abundant, and less toxic metals than other semiconductors. X-ray crystallography, electron microscopy, and atomic spectroscopy all helped confirm that the CZTS (copper, zinc, tin, and sulfur) semiconductor was suitable for use in a solar cell.
Thermoelectric materials can be used to turn waste heat into electricity or to provide refrigeration without any liquid coolants, and a research team from the University of Michigan has found a way to nearly double the efficiency of a particular class of them that's made with organic semiconductors.
An international team of researchers has recently succeeded in both initializing and reading nuclear spins—which are relevant to qubits for quantum computers—at room temperature. With the help of a spin filter developed in 2009, the team has produced a flow of free electrons with a given spin in a material.
Wake Forest University's Organic Electronics group has developed an organic semiconductor “spray paint” that can be applied to large surface areas without losing electric conductivity. The new spray-deposition method has the advantages of drop casting, spin coating, and prior spray-on techniques: It can applied to large surfaces of any medium, retaining electrical performance.
A team of electrical engineers from Columbia University has generated a record amount of power output—by a power of five—using silicon-based nanoscale CMOS technology for millimeter-wave power amplifiers. Power amplifiers are used in communications and sensor systems to boost power levels for reliable transmission of signals over long distances as required by the given application.
Unlike the building blocks of conventional hard disk drives and memories, resistive memory cells (ReRAM) are active electrochemical components. In these cells, ions generate voltage on electrodes in a similar manner to a battery. Researchers in Europe have conducted an extensive study of ReRAMs, also described as memristors, and have found previously undiscovered sources of voltage in these devices.