Graphene Semiconductors: Introduction and Market status - Page 4

Researchers from the University of Wisconsin-Milwaukee developed a new material called Graphene Monoxide (GMO) which is semiconducting. It's also may be easier to scale up compared to Graphene. This new material can provide the key towards graphene based electronics. The researchers say that they discovered GMO by chance...

In their experiments, the team heated Graphene Oxide in a vacuum, to reduce oxygen. But the results surprised them - the the carbon and oxygen atoms in the layers of GO became aligned, transforming themselves into an ordered semiconductor - the GMO.

Korean researchers fabricated a stretchable, transparent graphene-based transistor. They say that the new to transistor overcomes some of the problems faced by transistors made of conventional semiconductor materials - which simply cannot be made stretchable and transparent on substrates such as rubber slabs or balloons.

To make the transistor, the researchers synthesized single layers of graphene and then stacked them layer by layer on copper foil. Using photolithography and etching techniques, the researchers patterned some of the transistor’s essential elements, including the electrodes and semiconducting channel, onto the graphene. After transferring these components onto a stretchable rubber substrate, the researchers printed the remaining components gate insulators and gate electrodes onto the device using stretchable ion gel.

Finish researchers developed a new hybrid material which combines graphene nanoribbons and Single-Walled Carbon Nanotubes (SWNT). They call this GNR@SWNT - and they say that its synthesis is simple. The graphene nanoribbons should keep their unique properties inside the nanotubes, and they will be protected and aligned.

Nanoribbons can be either metallic or semiconductor (depending on their width and type) and the SWNTs can be either metallic, semiconducting (depending on their chirality) or insulating (when chemically modified). So you can create GNR@SWNT in six combinations which creates all sort sof interesting applications - transistors, solar cells, radio signal transmitters and more.

According to James Meindl (from the Georgia Institute of Technology) graphene will only become a viable alternative once CMOS semiconductor manufacturing will reach 7 nanometer - which will happen around 2024 (according to Moore's law).

Meindl believes that the most likely usages of graphene is switches - and he's working on 15 nanometer-wide ribbons that could rival silicon.

Researchers from the University of Manchester (in partnership with other scientists at the Universities of Moscow, Nijmegen and Lancaster) published some new information about the interactions between electrons in bilayer graphene.

The researchers utilized superior quality bilayer graphene instruments that were fabricated by suspending graphene sheets in vacuum (this method could remove majority of the unnecessary scattering methods of electrons in graphene, thus improving the electron to electron interaction effect).

Researchers from the National Institute of Standards and Technology (NIST) have shown that the electronic properties of two layers of graphene vary on the nanometer scale - not only in the strength of the electric charges between the two layers but they also actually reverse in sign to create randomly distributed puddles of alternating positive and negative charges.

This means that bi-layer graphene (two stacked graphene sheets) acts more like a semiconductor that a single sheet. A band gap may also form on its own due to variations in the sheets' electrical potential caused by interactions among the graphene electrons or with the substrate.

Researchers from the University of Illinois used a dry deposition method they developed to deposit pieces of graphene on semiconducting substrates and on the electronic character of graphene at room temperature they observed using the method. The reported their finding in a paper titled "Separation-Dependent Electronic Transparency of Monolayer Graphene Membranes on III-V Semiconductor Substrates".

The paper gives insight into a "understanding substrate-graphene interactions toward integration into future nanoelectronic devices". The project investigated the electronic character of the underlying substrate of graphene at room temperature and reports on "an apparent electronic semitransparency at high bias of the nanometer-sized monolayer graphene pieces observed using an ultrahigh vacuum scanning tunneling microscope (UHV-STM) and corroborated via first-principles studies." This semitransparency was made manifest through observation of the substrate atomic structure through the graphene.

A group of scientists from Germany, China and the US has created a Graphene-based transistor composed of 13 benzene rings. This molecule (called Coronene) shows an improved electronic band gap, a property which may help to overcome one of the central obstacles to applying graphene technology for electronics.

The team's new approach to make graphene is bottom up—building up the graphene, molecular piece by piece. To do this, Tao relies on the chemical synthesis of benzene rings, hexagonal structures, each formed from 6 carbon atoms. "Benzene is usually an insulating material, " Tao says. But as more such rings are joined together, the material's behavior becomes more like a semiconductor.

Researchers from UCLA has created a new Graphene nanostructure called Graphene nanomesh (GNM). The new structure is able to open up a band gap in a large sheet of graphene to create a highly uniform, continuous semiconducting thin film that may be processed using standard planar semiconductor processing methods.

The nanomesh can have variable periodicities, defined as the distance between the centers of two neighboring nanoholes. Neck widths, the shortest distance between the edges of two neighboring holes, can be as low as 5 nanometers. This ability to control nanomesh periodicity and neck width is very important for controlling electronic properties because charge transport properties are highly dependent on the width and the number of critical current pathways.

IBM Researchers has opened a bandgap for graphene field-effect transistors (FET) that could someday rival complementary metal oxide semiconductor. This is one of the last roadblocks to commercialization of Graphene-based technology, according to IBM.

Graphene has a higher carrier mobility than Silicon, but lacks a band gap, which has kept the on-off ratio of graphene transistors dismally low—usually less than 10 compared to hundreds for silicon. Now IBM says that they have managed to create a tunable electrical bandgap (up to 130meV) for their bi-layer graphene FETs. And larger bandgaps are possible, too.