Graphenea - Page 5

An international team of scientists collaborating in the Graphene Flagship project has developed a graphene-based transistor that reportedly outperforms previous state-of-the-art ones. The team utilized a thin top gate insulator material to optimize operational properties like maximum oscillation frequency, cutoff frequency, forward transmission coefficient, and open-circuit voltage gain, realizing devices that show prospect of using graphene in a wide range of electronic applications.

Graphene lack of a bandgap hinders its use in electronics since it causes an inability to switch the transistors off, effectively rendering the 0 state in digital logic inaccessible. However, many analog applications do not require a bandgap; The team explains that the only undesired side-effect of using GFETs in analog circuits is a poor saturation of the drain current, which prevents high-gain operation. The researchers have now succeeded in improving saturation by optimizing the dielectric material (AlOx) that is used to electrically insulate the top gate of the GFET. An improved quality of gate dielectric resulted in strong control over carriers in the graphene channel, yielding overall performance benefits.

Researchers from the ICFO have developed the first graphene-QDs-CMOS integrated camera, capable of imaging visible and infrared light at the same time. The camera may be useful for many applications like night vision, food inspection, fire control, vision under extreme weather conditions, and more.

The imaging system is said to be based on the first monolithic integration of graphene and quantum dot photodetectors, with a CMOS (complementary metal-oxide semiconductors) read-out integrated circuit. The implementation of such a platform in applications other than microcircuits and visible light cameras has been impeded by the difficulty to combine semiconductors other than silicon with CMOS, an obstacle that has been overcome in this work.

Researchers from the University of Hamburg and Graphenea have succeeded in upscaling high-quality graphene devices to the 100-micron scale and beyond. By perfecting CVD graphene production, transfer and patterning processes, the team managed to observe the quantum Hall effect in devices longer than 100 micrometers, with electronic properties on par with micromechanically exfoliated devices.

The work started from graphene grown by chemical vapor deposition (CVD) on a copper substrate. Since graphene on metal is not useful for applications in electronics, the material is usually transferred onto another substrate before use. The transfer process has proven to be a challenge, in many cases leading to cracks, defects, and chemical impurities that reduce the quality of the graphene.

Scientists from IEMN-CNRS, Graphenea, and Nokia have demonstrated flexible graphene transistors with a record high cut-off frequency of 39 GHz. The graphene devices, made on flexible polymer substrates, are stable against bending and fatigue of repeated flexing.

The graphene field effect transistor (GFET) is made from high quality CVD grown graphene with a carrier mobility of ~2500 cm2 V-1 s-1 on a flexible Kapton substrate with a thin alumina dielectric spacer in the channel region. The use of such sophisticated and optimized materials leads to the record high frequency performance as well as stability against bending. The GFET reportedly continues to operate even after 1,000 bending cycles and can be flexed to a radius of 12 mm with a cutoff frequency shift of up to 10%.

Researchers from Graphenea, Thales, CNRS, the University of Cambridge and GERAC have announced the development of a stable platform for manufacturing electronic devices made of graphene. Graphene field effect transistors (GFETs) made using this platform are shown to be stable against atmospheric influences and uniform in their properties across a batch of more than 500 devices.

The researchers reported on a statistical analysis and consistency of electrical performance of GFETs on a large scale. The devices were protected and passivated with two protective layers that ensured that the conductance minimum characteristic of electrical transport in graphene is visible most of the time and that it fluctuates very little from device to device. The intrinsic charge doping was below 5x1011 cm-2. In addition, this approach removed the hysteresis effect that usually degrades graphene device performance in air. Importantly, the devices were also stable in time, with unchanged performance over the course of one month.

Graphenea, a company focused on the production of high quality graphene for industrial applications, has announced a significant price reduction. The price of CVD films has dropped 15% on average this January, and the price of graphene oxide (GO) is being reduced by 30% on average.

CVD films are being offered on the copper substrates that they are grown on, in sizes ranging from 10x10 mm to 4 inch diameter. The same high quality graphene films are also available on SiO2/Si, quartz, PET, suspended on TEM grids and cavities, and on custom substrates as required. For customers wishing to do their own transfer, CVD graphene is also available on polymer films for easy transfer.

The Fraunhofer Institute FEP and other partners at EU GLADIATOR project developed a functional flexible OLED lighting device based on graphene electrodes. This device is 2 x 1 cm in size - much larger the previous prototype developed as part of that project last year.

The graphene electrodes were produced in a CVD-based process. The graphene was deposited on a copper film, covered with a flexible polymer carrier and then the copper was etched away.

Project GRAMOFON, a 3.5 year project that started in October 2016, aims to establish a process for efficient CO2 capture by innovative adsorbents based on modified graphene aerogels and MOF materials. The EU will contribute nearly €4.2 million to the project.

The key objectives of GRAMOFON projects are:

• to develop and prototype a new energy and cost-competitive dry separation process for post-combustion CO2 capture based on innovative hybrid porous solids Metal organic frameworks (MOFs) and Graphene Oxide nanostructures.
• to optimize the CO2 desorption process by means of Microwave Swing Desorption (MSD) and Joule effect, that will surpass the efficiency of the conventional heating procedures.

Graphenea launched a new graphene transfer procedure, which they call "Easy Transfer". The CVD graphene maker says this is the easiest way to transfer mono layer graphene onto any substrate. The Easy Transfer process avoids metal etching and any hazardous chemical handling, and the thin film manipulation is done at Graphenea's plant.

Easy Transfer is available in 1x1 cm and 1x1 inch sizes, and can be used to cut lead time and research work. Companies are welcome to send their substrates to Graphenea for coatings. The price for this process is $80 for 1x1cm and $120 for 1x1 inch.

Graphenea, the Spain-based graphene producer, has teamed up with scientists from the Delft University of Technology in the Netherlands to design graphene-based "mechanical pixels" that could, among other applications, be someday used as colored pixels in e-readers and other low-powered screens.

In these "graphene balloons", a double layer of graphene (two atoms thick) is deposited on top of circular indents cut into silicon. The graphene membranes enclose air inside the cavities, and the position of the membranes can be changed by applying a pressure difference between the inside and the outside. When the membranes are closer to the silicon they appear blue; when the membranes are pushed away they appear red.