Graphene Semiconductors: Introduction and Market status - Page 3

A joint research team of Korean scientists from the Korea Research Institute of Standards and Science (KRISS) and Hungarian scientists from the Center of Natural Sciences developed a new way of producing graphene nanoribbons, to be used as a semiconductor element. The graphene nanoribbon is between 2 to 10 nm in size with edge frame form that can be controlled at room temperature. Its production was achieved by using a technology called scanning tunneling lithography (STL), where the scientists succeeded in cutting the shape of the nanoribbon edge as they wished.

In addition, the research team discovered a phase transition phenomenon changing the graphene nanoribbon either to semiconductor or metal depending on increase or decrease in their width, which raised the possibility for its commercialization.

Manchester University's graphene Nobel laureate Sir Andre Geim, together with Leonid Levitov from MIT discovered that electrons in a graphene superlattice move at a controllable angle to applied fields - this is like sailboats that sail diagonally to the wind.

A graphene superlattice is made from a sheet of graphene aligned on top of a sheet of boron nitride. This material behave as a semiconductor (unlike graphene itself which is a superconductor). The researchers found that the electrons in the new material behave as neutrinos that acquired a notable mass. This effect has no known analog in particle physics.

IBM developed a new method to use graphene as a substrate for single-crystalline semiconductor film growth. Graphene will be less expensive than current single-crystalline wafers used in such production methods, as it can be reused indefinitely.

IBM says that growing a 4" GaN film today requires a 4" SiC substrate wafer which is destroyed using the process. The SiC costs about $3,000. Graphene can be used to replace the SiC and will be much cheaper in the long run. Graphene is also useful as it is flexible and can be better adapted for films that need to be transferred to a flexible substrate.

Researchers from the University of Arizona discovered how to change the crystal structure of graphene with an electric field. This unique technique may enable graphene transistors - and electronics and microprocessors applications.

The researchers used trilayer graphene, in which the top layer can be placed in two different ways - either the atoms are placed on the atoms of the bottom layer or with a slight offset (so the atoms are placed on the space between the bottom layer atoms). In a tri-layer graphene sheet, this happens naturally and actually the two stacking configurations exist together with a sharp boundary between them.

Researchers from the University of Luxembourg developed a new materiel which resembles graphene but is made from "traditional semiconductor materials". This so-called "artificial graphene" could be useful in many applications, including electronics, optics, solar cells, lasers and LEDs.

The artificial graphene has the same honeycomb structure as graphene, but it uses nanometer-thick semiconductor crystals instead of carbon atoms. The material's properties can be tuned by changing the size, shape and chemical nature of those nano crystals.

Researchers from Purdue University developed a new graphene-like 2D material from phosphorus. They call the new material phosphorene and they say that this is the first native 2D p-type semiconductor, making it more useful than graphene to make transistors.

Together with MoS₂ (a 2D n-type semiconductor), it is now possible to build switches made from 2D materials. Graphene in its basic form is a superconductor and so is less suited to make transistors.

Researchers from Korea's Institute for Basic Science (IBS) developed a new way to synthesize single-layer molybdenum disulphide (MoS₂) using a gold catalyst. This new method allows MoS₂ to be synthesized within a large area and any desired geometrical shape, and to be produced in the form of a semiconductor device.

The researched used the principle that a surface alloy is formed through the separation of molybdenum atoms and mixing them with gold when a chemical compound containing molybdenum is injected onto the surface of gold.

A few month ago we reported on Carbyne, a chain of carbon atoms linked either by alternate triple and single bonds or by consecutive double bonds, which was found to be twice as strong as graphene. Carbyne is difficult to synthesize (it does not exist in nature, but it may exist in interstellar space) but a few years ago researchers managed to make carbyne chains up to 44 atoms long in solution.

Now researchers from Rice University have performed more theoretical calculations on this new material. They say that a Carbyne nano-rod (also called nano-ropes) is pretty much like a very thin (one-atom wide) graphene ribbon. When you twist this nano-rod, you change the band gap of the material.

Researchers from the University of Vienna managed to assemble a new structure of high-quality metal silicides (nickel, cobalt and iron) coated with a graphene sheets. Using angle-resolved photoemission spectroscopy (ARPES), the researchers studied the electronic properties of this new material.

It was found that the graphene protects the silicides against oxidation, while barely interacting with the silicides themselves. The unique properties of the graphene are widely preserved. This means that this new composite material is a good way to incorporate graphene with existing metal silicide technology, which will hopefully enable the usage of graphene in applications such as semiconductor devices, spintronics, photovoltaics and thermoelectrics.

Researchers from Australia discovered that molybdenum oxides can be used to improve graphene’s charge-carrying capabilities. This can results in devices that are smaller and/or enable faster data transfer.

The researchers created new sheets of this hybrid material using exfoliation. Those sheets are 11 nanometers thick and can be turned into a semiconductor (to fabricate transistors for example). The final device features an electron mobility greater than 1,100 cm²/Vs - higher than the current standard for low dimensional silicon.