Boron Nitride

Researchers show that hydrodynamic electrons flow through materials without electrical resistance

Scientists from Israel's Weizmann Institute of Science, in collaboration with teams at Manchester University and UC Irvine,  have shown that an electronic fluid can flow through materials without any electrical resistance, thereby perfectly eliminating a fundamental source of resistance that forms the ultimate limit for ballistic electrons. This result could open the door to improved electronic devices that do not heat up as much as existing technologies.

When electrons flow in electrical wires, they lose part of their energy, which is wasted as heat. This heating is a major problem in everyday electronics. The heating occurs because electrical conductors are never perfect and have a resistance for the flow of electrical currents. Typically, this resistance originates from the scattering of the flowing electrons by imperfections in the host material. But it stands to reason that a perfect conductor, devoid of any imperfections, would have zero resistance. However, even if the conductor is perfectly clean and free from imperfections, the resistance does not vanish. Instead, a new source of resistance emerges, known as the Landauer-Sharvin resistance. In an electrical conductor, electrons flow in quantum channels, much like cars in highway lanes. Similar to highway lanes, each electronic channel has a finite capacity to conduct electrons, limited by the quantum of conductance. For a given conductor, the number of quantum channels is finite and determined by its physical width. Thus, even a perfect electronic device, devoid of any imperfections, will never have infinite conductance. It will always have resistance. In the absence of interactions between electrons, this Landauer-Sharvin resistance is unavoidable, putting a fundamental lower bound on the heating of computer chips, which becomes even more severe as transistors become smaller.

Read the full story Posted: Sep 14,2022

Researchers develop graphene-based foam composite for efficient water filtration

While graphene-based materials have potential as adsorbent materials, their performance can be hindered due to aggregation and a lack of control over their porosities and dimensions. The researchers in a recent study, from the University of Exeter, Kyushu University and the University of Oxford, have addressed this issue by developing a unique graphene material combined with a high porosity composite foam to combat aggregation.

Pharmaceuticals are among the most prominent emerging contaminants (ECs) in water systems. They may cause severe environmental consequences along with potential health problems. To successfully eradicate ECs from processed wastewater streams, effluent and drinking water purification facilities must adopt adequate tertiary treatment methods. Adsorption is regarded as a technology with great potential in water treatment as it is dependable and less expensive compared to reverse osmosis, oxidizing, microfiltration, ultrafiltration, ion exchange, etc.

Read the full story Posted: Jun 07,2022

Researchers succeed in synthesizing single layers of hexagonal boron nitride on graphene

A research team led by the University of Michigan has developed a reliable, scalable method for growing single layers of hexagonal boron nitride on graphene.

Graphene-hBN structures can power LEDs that generate deep-UV light, which is impossible in today's LEDs, said Zetian Mi, U-M professor of electrical engineering and computer science and a corresponding author of the study. Deep-UV LEDs could drive smaller size and greater efficiency in a variety of devices including lasers and air purifiers.

Read the full story Posted: Apr 24,2022

Researchers detect evidence of strong electron correlation in a trilayer graphene/hBN moiré superlattice

Researchers from MIT, Harvard University, University of California at Berkeley, Lawrence Berkeley National Laboratory, China's Shanghai Jiao Tong and Fudan Universities and Japan's National Institute for Materials Science have taken a significant step toward understanding electron correlations.

In their new study, the researchers revealed direct evidence of electron correlations in a two-dimensional material called ABC trilayer graphene. This material has previously been shown to switch from a metal to an insulator to a superconductor.

Read the full story Posted: Mar 22,2022

Redmi K50 e-sports version sports an advanced graphene-based cooling system

Graphene-based cooling systems are becoming quite popular in today's cellphones, with many companies using it in their models. A few examples are: realme's GT 2 series, ZTE's Axon 30, Xiaomi's Mi 10 Ultra, various Huawei phones and more.

REDMI K50 E-SPORTS uses graphene cooling systems image

Now, it seems that Redmi's K50 e-sports has joined this team, with a recent disassembly test that found that its heat dissipation system makes use of graphene films. The test also reported 3D high-power graphite, large-area double VC, and heat dissipation copper sheet + boron nitride.

Read the full story Posted: Feb 22,2022

Graphene and hBN nano-additives improve eco-friendly lubricant oils

Researchers from the University of Nevada have investigated the introduction of graphene nanoplatelets (GNPs) and hexagonal boron nitride (hBN) to canola oil to improve its tribological properties, as part of an effort to reduce the usage of lubricants based on petroleum as lubricants for reducing abrasion and friction.

Three nanoscale lubricating combinations were created by combining both GNP and hBN settings in varied ratios to get the best beneficial synergy. The team reports that lubrication quality and performance may be increased by using low-weight percentages of nanoparticle (NP) and microparticle additions. One benefit is that it has a reduced coefficient of friction (COF) and wearing.

Read the full story Posted: Jan 05,2022

Boron nitride assists in protecting graphene in order to achieve next-gen electronics

Researchers from AMO, Oxford Instruments, Cambridge University, RWTH Aachen University and the University of Wuppertal have demonstrated a new method to use plasma enhanced atomic layer deposition (PEALD) on graphene without introducing defects into the graphene itself.

Currently, the most advanced technique for depositing dielectrics on graphene is atomic layer deposition (ALD), which allows to precisely control the uniformity, the composition and the thickness of the film. The process typically used on graphene and other 2D materials is thermal water-based ALD, as it does not damage the graphene sheet. However, the lack of nucleation sites on graphene limits the quality of the dielectric film, and requires the deposition of a seed layer prior to ALD to achieve good results. Another approach is plasma enhanced atomic layer deposition (PEALD), which, when applied to growth on graphene, can introduce surface damage. This is what to team addressed in this recent work.

Read the full story Posted: Aug 09,2021

Researchers show that stretching can change the electronic properties of graphene

A research team led by the University of Basel has found that the electronic properties of graphene can be specifically modified by stretching the material evenly.

The researchers, led by Professor Christian Schönenberger at the Swiss Nanoscience Institute and the Department of Physics at the University of Basel, have studied how the material’s electronic properties can be manipulated by mechanical stretching. In order to do this, they developed a kind of rack by which they stretch the atomically thin graphene layer in a controlled manner, while measuring its electronic properties.

Read the full story Posted: Jun 29,2021

Researchers report a highly efficient graphene/hBN-based electro-absorption modulator

ICFO researchers led by Professor Frank Koppens, in collaboration with researchers from Universita di Pisa, CNIT, Ghent University-IMEC, and NIMS, have reported a novel electro-absorption (EA) modulator capable of showing a 3-fold increase in static and dynamic modulation efficiency while maintaining the high-speed, a value that surpasses those for previously reported graphene EA modulators.

 Electrical connections and schematic cross-section of an EA modulator with an hBNHfO2hBN dielectric image

To achieve this, the team of researchers developed a high-quality graphene-based electro-absorption modulator by combining high-quality graphene and a high-k dielectric, also used in microelectronics. The high quality of the graphene was achieved by integrating it with the 2d-material dielectric hexagonal boron nitride (hBN).

Read the full story Posted: Feb 16,2021

Scientists discover important new property of graphene

MIT researchers and colleagues have discovered a new and important electronic property of graphene. The work, which involves structures composed of atomically thin layers of materials that are also biocompatible, could usher in new, faster information-processing paradigms. One potential application is in neuromorphic computing, which aims to replicate the neuronal cells in the body responsible for everything from behavior to memories.

Graphene-based heterostructures continue to produce fascinating surprises. Our observation of unconventional ferroelectricity in this simple and ultra-thin system challenges many of the prevailing assumptions about ferroelectric systems and it may pave the way for an entire generation of new ferroelectrics materials, says Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics at MIT and leader of the work, which involved a collaboration with five other MIT faculty from three departments.

Read the full story Posted: Jan 27,2021