Boron Nitride - Page 10

Researchers from Berkeley Lab and the University of California (UC) Berkeley developed a method to open a bandgap in a graphene boron-nitride (GBN) heterostructure using visible light. Using this so called "photo-induced doping" of the GBN the researchers created pn junctions and other useful doping profiles while preserving the material’s remarkably high electron mobility.

Using visible light is very promising as this technique is very flexible and (unlike electrostatic gating and chemical doping) does not require multi-step fabrication processes that reduce the graphene's quality. Using this method, one can make and erase different patterns easily.

Researchers from the University of Manchester demonstrated that when growing graphene on a hexagonal substrate (hBN, or hexagonal Boron-Nitride, in that case), small changes in the crystal structure can open a band-gap in the graphene. The researchers also demonstrated that a graphene grown on the hBN can exist in an alternative structure in which the band gap is much smaller.

The lattice structure of hBN (also called white graphene) is quite similar to graphene. When you place the graphene on top of the hBN, a moiré superlattice is created. The periodic potential associated with this superlattice causes a number of new and interesting electronic phenomena to occur in graphene, including Hofstadter's butterfly, which has been shown before.

Researchers from Italy's Institute of Organic Synthesis and Photoreactivity (ISOF) developed a new way to analyze the production process of 2D materials (such as BN or graphene). The new suggested process can be used for process control of 2D and composite materials produced via exfoliation.

The researchers explain that today there are many different methods and production processes used to produce graphene. But it is difficult today to compare the quality of these materials. The new suggested method may help to better understand these different materials and standardize their quality.

Researchers from Brown University have shown that it is possible to create a graphene-like 2D material from Boron. This new materiel (termed Borophene) may prove to be an even better conductor than graphene.

Boron has one fewer electron than carbon so it cannot form a honeycomb lattice. But now it turns out that you can make a cluster of 36 Boron atoms (shown on the left in the image above) called B36 that looks like a disc with a hexagonal hole in the middle. This B36 can be used to form an extended planar 2D graphene-like material.

Researchers from the University of Twente have looked into graphene's behavior when it is placed on boron nitride. It turns out that if the graphene is placed in a certain angle over the BN, it opens a bandgap. If it is placed in a random angle, the band gap will not open.

The researchers also discovered that if the graphene/BN structure is placed on copper, that can be contacted with other devices, a charge distribution (dipole layer) is also formed on the interface between copper and boron nitride.

Researchers from MIT developed a new process that can transfer graphene directly onto a variety of flexible substrates using a lamination process that does not require an intermediate "glue" step. The new process does not leave any residues that can affect the graphene like in other transfer processes. The new method can also be used for other materials, such as boron nitride.

The process starts by synthesizing graphene flakes on both sides of a copper foil sheet. Then the flakes are sandwiched between the target flexible surface and a protective paper layer. This structure is placed between two plastic (PET) sheets. This goes into a lamination machine in which the temperature can be controlled, and the components bond together. The plastic film and paper where removed and this leaves a copper foil with graphene and the target substrate. The copper was dissolved (or etched away) using a copper etchant.

Researcher from Columbia University demonstrated that it is possible to electrically contact an atomically thin graphene (or any 2D material) only along its edge (rather than contacting it from the top). This new architecture enabled a new assembly technique that prevents interface contamination. This new assembly process resulted in the cleanest graphene ever made. They say that the new edge-contact geometry actually provides a more efficient contact without the need for complex processing.

This research work solved two graphene problems - contamination and contact. Having contacts just at the edges virtually eliminates external contamination. To achieve this breakthrough, the researchers fully encapsulated a single graphene sheet in a sandwich of thin insulating boron nitride crystals, employing a new technique in which crystal layers are stacked one-by-one.

Aixtron reported today that the company is involved with several European graphene research projects. In fact, Aixtron says they are a key-partner in several EU projects. First of all, Aixtron is leading Production Work Package in the Graphene Flagship, EU's $1 billion graphene drive.

In the GRAFOL project, Aixtron applies their scaling know-how to develop large scale equipment for wafer-based graphene and continuous production of foil-based graphene for transistors and transparent conductive films. In another project called MEM4WIN Aixtron employs their batch-based deposition technology to improve the throughput of graphene production for smart windows.

Researchers from Rice University have discovered that hexagonal Boron Nitride (h-BN, which has a similar structure to graphene and is sometimes referred to as "white graphene") may be used as a very effective anti-rust metal coating that can prevent the metal from oxidizing at very high temperatures (up to 1,100 degrees Celsius). Even while layer of h-BN may be enough to be used as a protective coating.

The researchers made small sheets of h-BN on nickel foil using CVD. They say that the process should be scalable for industrial production. The researchers also tested growing h-BN on graphene, and transferring h-BN sheets to copper and steel.

Veeco Instruments announced that the University of Nottingham in the UK purchased two GENxplor R&D Molecular Beam Epitaxy (MBE) Systems for its School of Physics and Astronomy. The University will use the systems to grow high-quality large-area graphene and boron nitride for electronic and optoelectronic applications.

Veeco's MBE systems can deposit epitaxial graphene layers on substrates up to 3" in diameter. The company says that their vertical chamber technology enables them to build smaller MBE systems - up to 40% smaller than the competition. The MBE is an open architecture that provides convenient access to effusion cells and e-beam sources.