Boron Nitride - Page 11

Researchers from Rice University and the Oak Ridge National Laboratory (ORNL) found a new method to control the growth of uniform atomic layers of molybdenum disulfide (MDS), a semiconductor together with graphene can be used to make 2D electronic devices. Unlike graphene, MDS has a band gap.

The researchers goal is to create large MDS sheets (using CVD) and then use it together with graphene and the insulator hexagonal boron nitride (hBN) to form field-effect transistors, integrated logic circuits, photodetectors and flexible optoelectronics. MD5 isn't flat - it's actually a stack, with a layer of molybdenum atoms between two layers of sulfur atoms. It's a challenge to actually bind these three materials together.

A worldwide team of researchers (from the US and Japan) managed to observe Hofstadter’s butterfly fractal pattern for the first time. This pattern was predicted by Douglas Hofstadter back in 1976 - and it emerges when electrons are confined to a two-dimensional sheet, and subjected to both a periodic potential energy and a strong magnetic field.

To create the periodic potential energy, the researchers used an effect called a moiré pattern that arises naturally when graphene is placed on a flat boron nitride substrate. Mapping the graphene energy spectrum (by measuring the electronic conductivity of the samples at very low temperatures in extremely strong magnetic fields, up to 35 Tesla) showed the predicted fractal pattern. The actual mapping can be seen below:

Researchers from the Universities of Manchester and Nottingham developed a new ultra-fast bi-stable graphene transistor. They say that such transistors may enable new medical imaging and security devices.

A bi-stable transistor means that it can spontaneously switch between two electronic states. This new device is made from two layers of graphene separated by a boron nitride insulating layer. By applying a small voltage, you can tune the electron clouds in the graphene layers which induces the electrons so they move at high speed between the layers (by quantum tunneling over the thin insulating layer). This emits high-frequency electromagnetic waves (in the range between radar and infra-red).

Researchers are using Boron Nitride nanosheets to soak up organic pollutants such as industrial chemicals or engine oil. It turns out that this material (which is similar to graphene and sometimes referred to as "white graphene") is better than Graphene for this task.

Boron Nitride have an great area-to-weight ratio which means that they can soak a lot of material compared to their size (up to 33 times its own weight, depends on the pollutant it is soaking) . The researchers use porous sheets (sheets with holes in them) and these exhibit high "selective absorption and adsorption".

The UK's Engineering and Physical Sciences Research Council (EPSRC) awarded the University of Nottingham with £1.3 million (just over $2 million) that will be used to buy a new molecular beam epitaxy (MBE) system. This new system will enable the growth of high quality, large area layers of graphene and boron nitride.

Researchers from the University plan to study new materials based on graphene and boron nitride for electronic and optoelectronic applications.

Researchers from the University of Manchester discovered that sandwiching graphene between boron nitride layers can produce highly-accurate capacitors. Such capacitors could be cheaper and easier to fabricate compared to traditional transistors.

The researchers used quantum capacitance spectroscopy to investigate the exceptional properties of graphene, as this measurements shows better accuracy.

Graphene Laboratories is expanding their product line, and now they offer new 2D graphene-like materials. The new materials include liquid suspensions of atomically thin molybdenum disulfide (MoS2), tungsten disulfide (WS2) both transition metal dichalcogenides (TMD’s) and boron nitride (BN).

The new materials are available at Graphene Lab's online store.

Scientists from the University of Manchester, including Nobel prize-winner Professor Andre Geim constructed a multi-layer graphene structure made by placing individual sheets one on top of the other. This 'cake' like structure behaves like a nanoscale electric transformer - which could be used to make new electronic transistors and photonic detector devices.

In the new device, electrons moving in one metallic layer pull electrons in the second metallic layer by using their local electric fields. The layers are only separated by a tiny (few interatomic) distance - much shorter than anything done before. To achieve this structure they used just four atomic layers of boron nitride to serve as an electric insulator.

Researchers from Cornell University have managed to pattern single atom films of graphene and boron nitride, an insulator, without the use of a silicon substrate. They are using a technique they call patterned regrowth, and they say this could lead towards substrate-free, atomically thin circuits. These will be so thin that they could be transparent and flexible, and yet have great electrical performance.

Patterned regrowth uses the same basic photolithography technology used in silicon wafer processing, and it allows graphene and boron nitride to grow in perfectly flat, structurally smooth films. The researchers first grew graphene on copper and used photolithography to expose graphene on selected areas, depending on the desired pattern. They filled that exposed copper surface with boron nitride, the insulator, which grows on copper and fills the gaps. Then you simply peel off the entire structure.

Researcher from MIT discovered that graphene's basic properties (chemical reactivity, electrical conductivity and others) can vary dramatically based on the substrate material it is placed on. When placed on silicon dioxide, graphene becomes functionalized when exposed to certain chemicals, but when the substrate is boron nitride, the graphene is inert to the same chemicals.

The research, funded by the US Office of Naval Research, means that you can control the graphene ability to create chemical bonds - using different underlying materials.