Borophene has a nearly perfect partner in a form of silver that could help the trendy two-dimensional material grow to unheard-of lengths.
A well-ordered lattice of silver atoms makes it possible to speed the growth of pristine borophene, the atom-thick allotrope of boron that so far can only form via synthesis by molecular-beam epitaxy (MBE).
By using a silver substrate and through careful manipulation of temperature and deposition rate, scientists have discovered they can grow elongated hexagon-shaped flakes of borophene. They suggested the use of a proper metal substrate could facilitate the growth of ultrathin, narrow borophene ribbons.
New work published in Science Advances by researchers at Rice and Northwestern universities, Nanjing University of Aeronautics and Astronautics and Argonne National Laboratory will help streamline the manufacture of the conductive material, which shows potential for use in wearable and transparent electronics, plasmonic sensors and energy storage.
That potential has fueled efforts to make it easier to grow, led by Rice materials scientist Boris Yakobson, a theorist who predicted that borophene could be synthesized. He and collaborators Mark Hersam at Northwestern and lead author Zhuhua Zhang, a Rice alumnus and now a professor at Nanjing, have now demonstrated through theory and experimentation that large-scale, high-quality samples of borophene are not only possible but also allow qualitative understanding of their growth patterns.
Electrical engineering researchers have boosted the operating temperature of a promising new semiconductor laser on silicon substrate, moving it one step closer to possible commercial application.
The development of an “optically pumped” laser, made of germanium tin grown on silicon substrates, could lead to faster micro-processing speed of computer chips, sensors, cameras and other electronic devices—at much lower cost.
“In a relatively short time period—roughly two years—we’ve progressed from 110 Kelvin to a record temperature of 270K,” said Shui-Qing “Fisher” Yu, associate professor of electrical engineering. “We are now very close to room-temperature operation and moving quickly toward the application of a material that can significantly increase processing speed with much less power consumption.”
Yu leads a multi-institutional team of researchers on developing a laser injected with light, similar to an injection of electrical current. The improved laser covers a broader wavelength range, from 2 to 3 micrometers, and uses a lower lasing threshold, while capable of operating at 270 Kelvin, which is roughly 26 Farenheit.
What makes something a crystal? A transparent and glittery gemstone? Not necessarily, in the microscopic world. When all of its atoms are arranged in accordance with specific mathematical rules, we call the material a single crystal. As the natural world has its unique symmetry, e.g., snowflakes or honeycombs, the atomic world of crystals is designed by its own rules of structure and symmetry. This material structure has a profound effect on its physical properties as well. Specifically, single crystals play an important role in inducing a material’s intrinsic properties to its full extent. Faced with the coming end of the miniaturization process that the silicon-based integrated circuit has allowed up to this point, major efforts have been dedicated to find a single crystalline replacement for silicon.
In the search for the transistor of the future, two-dimensional (2-D) materials, especially graphene, have been the subject of intense research around the world. Being thin and flexible as a result of being only a single layer of atoms, this 2-D version of carbon even features unprecedented electricity and heat conductivity. However, the last decade’s efforts for graphene transistors have been held up by physical restraints—graphene allows no control over electricity flow due to the lack of band gap. So then, what about other 2-D materials? A number of interesting 2-D materials have been reported to have similar or even superior properties. Still, the lack of understanding in creating ideal experimental conditions for large-area 2-D materials has limited their maximum size to just a few millimeters.
Nano-microfiber Composites For Filtration
Nanofibers prepared by molecular self-assembly are in general not self-supporting and therefore require stabilizing scaffold structures. In fact, a lot of research in the past has been done with supramolecular self-assembly of molecules forming a network of nanofibers used as organo/hydrogelators. But efforts to use them as a self-standing membrane or as free fibers were not strong. Therefore, the self-assembly of trisamides was also tried on a substrate, i.e., other microfiber nonwovens, leading to microenanofiber composites (Fig. 4.4) used for filtration (Weiss et al., 2016).
Creating two-dimentional materials large enough to use in electronics is a challenge despite huge effort but now, Penn State researchers have discovered a method for improving the quality of one class of 2-D materials, with potential to achieve wafer-scale growth in the future.
The field of 2-D materials with unusual properties has exploded in the 15 years since Konstantin Novoselov and Andre Geim pulled a single atomic layer of carbon atoms off of bulk graphene using simple adhesive tape. Although a great amount of science has been conducted on these small fragments of graphene, industrial-sized layers are difficult to grow.
Of the materials envisioned for next-generation electronics, a group of semiconductors called transition metal dichalcogenides are at the forefront. TMDs are only a few atoms thick but are very efficient at emitting light, which makes them candidates for optoelectronics such as light-emitting diodes, photodetectors, or single-photon emitters.