Electronics, computing, and information technology

Researchers from the University of California San Diego have developed an innovative approach to multispectral photodetection by alternating layers of graphene and colloidal quantum dots. By carefully engineering the material stack, the researchers created photodetectors sensitive to different wavelength bands without additional optical components. The key innovation lies in using graphene monolayers as independent charge collectors at different depths within a quantum dot absorber layer.

Researchers from Florida State University, the University of California Santa Barbara, Tsinghua University in China, Leipzig University in Germany, and Stuttgart University in Germany have identified, for the first time, the existence of local collective excitations of #electrons, called #plasmons, in a #Kagome metal – a class of materials whose atomic structure follows a hexagonal pattern that looks like a traditional Japanese basket weave – and found that the wavelength of those plasmons depends upon the thickness of the metal.

Scientists from the Massachusetts Institute of Technology, Arizona State University, the U.S. Department of Energy’s Brookhaven National Laboratory, Sorbonne University in Paris, France, and Utrecht University in the Netherlands have reported new insights into exotic particles that are key to a form of magnetism that originates from ultrathin materials only a few atomic layers thick. The scientists identified the microscopic origin of these particles, known as excitons, and showed how they can be controlled by chemically “tuning” the material, which is primarily composed of nickel.

Physicists from Purdue University, Washington University in St. Louis, and the U.S. Department of Energy’s Sandia National Laboratories have levitated a fluorescent nanodiamond and spun it at incredibly high speeds (up to 1.2 billion times per minute). The fluorescent diamond emitted and scattered multicolor lights in different directions as it rotated. When illuminated by a green laser, the nanodiamond emitted red light, which was used to read out its electron spin states. An additional infrared laser was shone at the levitated nanodiamond to monitor its rotation.

Researchers from the University of California, Santa Barbara, The Ohio State University, and the University of Hong Kong have, for the first time, characterized the thermoelectric properties of high-quality cadmium arsenide thin films. The researchers created three high-quality films of varying thicknesses – 950 nanometers (nm), 95 nm, and 25 nm – and found that the thinner the material, the higher the thermoelectric sensitivity, resulting in more voltage in response to a temperature gradient, a response enhanced by seven times compared to the state-of-the-art material.

Researchers from the U.S. Department of Energy’s Los Alamos National Laboratory (LANL) and Lawrence Berkeley National Laboratory (LBNL) and Seoul National University in South Korea have developed a way to directly measure such materials' thermal expansion coefficient, the rate at which the material expands as it heats. Due to the thinness of two-dimensional materials, until now, measuring their thermal expansion could only be accomplished indirectly or with the use of a support structure called a substrate.

This video (with related transcript) describes the recent expansion of the semiconductor manufacturing sector in the United States and how community colleges and universities are providing the relevant training to help fill semiconductor manufacturing jobs. The video focuses on Arizona and features Taiwan Semiconductor Manufacturing Company (TSMC), which is building a semiconductor manufacturing facility in Phoenix, AZ, as well as Arizona State University, Rio Salado College, and Maricopa Community College. 

Researchers at Michigan State University have developed a new technique that combines atomic-scale imaging with extremely short laser pulses to detect single-atom defects that manufacturers add to semiconductors to tune their electronic performance. “This is particularly relevant for components with nanoscale structures,” said Tyler Cocker, a scientist who led this study. The technique is straightforward to implement with the right equipment, he added, and his team is already applying it to atomically thin materials, such as graphene nanoribbons.

Researchers from the U.S. Department of Energy's Princeton Plasma Physics Laboratory and the University of Delaware have provided new insights into the variations that can occur in the atomic structure of two-dimensional materials called transition metal dichalcogenides (TMDs). The researchers found that one of the defects, which involves hydrogen, provides excess electrons. The other type of defect, called a chalcogen vacancy, is a missing atom of oxygen, sulfur, selenium, or tellurium.

Researchers from the U.S. Department of Energy’s SLAC National Accelerator Laboratory and Argonne National Laboratory; Stanford University; Harvard University; Columbia University; Florida State University; and the University of California, Los Angeles, have discovered new behavior in an 50-nanometer-thick two-dimensional material, which offers a promising approach to manipulating light that will be useful for devices that detect, control or emit light, collectively known as optoelectronic devices.