Graphene is made at industrial scale today using chemical vapor deposition (CVD) to grow the material from the bottom up on copper foils. CVD-grown graphene is polycrystalline and cannot shuttle electrons and positively charged holes as quickly as single-crystal material—and speed is essential for high-performance electronic devices. In addition, when the CVD flakes are transferred to insulating substrates to make devices, metal atoms often contaminate the graphene, and mechanical stress wrinkles it. The new technique gives centimeters-wide, wrinkle-free single sheets of graphene with no overlapping layers. Such high-quality graphene grown directly on an insulating surface should pave the way for high-performance electronics and optoelectronic devices made from graphene, according to Rodney S.
by Prachi Patel, special to C&EN | January 30, 2022
Entegris produces organometallic precursor chemicals that are deposited onto chip surfaces via chemical vapor deposition or atomic layer deposition, creating ultra-thin films. CMC supplies the slurries and polishing pads needed to smooth those films to be ultra-flat. Entegris comes back in the process with slurry containers and filtration devices as well as post-CMP cleaning chemicals, filters, and brushes.
by Michael McCoy | December 15, 2021
Iron-based MOFs containing azolate linkers, which are heterocycles with nitrogen atoms, exhibit some of the highest conductivities in this category. Another mechanism, known as the extended conjugation pathway, also involves bonds between the metal atoms and the linkers. But in this pathway, the organic linkers contain functional groups, such as diamines and dithiols, that are conjugated with the linker’s carbon core. Other pathways feature charge transport between adjacent molecular layers in a MOF. This so-called through-space pathway is common in MOFs with naphthalenes, anthracenes, and other aromatic groups. Each molecular layer of these MOFs stacks like playing cards via interactions between the π bonds in the MOF’s aromatic rings.
by Mitch Jacoby | November 28, 2021
PDH plants convert propane to propylene at temperatures of 600 °C or more, and these conditions generate sooty carbon deposits that quickly deactivate the catalysts. To solve these problems, researchers have spent decades developing the oxidative dehydrogenation of propane (ODHP), in which the hydrogen freed from propane is immediately combined with oxygen to create water.
by Mark Peplow, special to C&EN | March 24, 2021
Researchers now report an ultrafast way to peel graphene flakes up to a few atoms thick from graphite by using a high-temperature plasma spray process (ACS Nano 2021, DOI: 10.1021/acsnano.0c09451).Exfoliation techniques that involve lifting monolayers of carbon atoms from graphite yield very small amounts of graphene, sometimes with defects. Chemical vapor deposition (CVD), the leading method of mass-producing graphene, requires multiple steps and is expensive.Anup Kumar Keshri of the Indian Institute of Technology Patna and his team made graphene by loading graphite particles into a plasma spray gun, which melts powdered materials in a jet of plasma—a high-temperature gas of ions. The plasma spray ripped apart the graphite into graphene flakes; the researchers collected the resulting powder, put it in deionized water, and spun it in a centrifuge to remove unexfoliated clumps of graphite.Analysis with microscopy and spectroscopy methods showed that 85% of the graphene flakes were a single atomic layer and the rest had a few layers.
by Prachi Patel, special to C&EN | February 20, 2021
Roger Hannah and Neil Sheehan, public affairs officers for US Nuclear Regulatory Commission operations in the Southeast and Northeast US, respectively, confirm that the Turkey Point Nuclear Plant, 40 km south of Miami, and Peach Bottom Atomic Power Station, 80 km southeast of Harrisburg, recently received additional extensions that would allow them to continue operating for a total of 80 years each.
by Mitch Jacoby | September 20, 2020
In the past few years, he has become a specialist in atomic layer deposition (ALD), a surface coating technique for making nanostructured materials and electronic devices. Wojtecki also found time to study quantum computing—now he’s an IBM spokesperson on the subject—and he even invented a new method for decaffeinating coffee.
by Mitch Jacoby | August 14, 2020