Graphene-based transistors show promise for optical technologies

Apr 18, 2017

Researchers at Purdue University, the University of Michigan and Pennsylvania State University have combined graphene with a (comparatively much larger) silicon carbide substrate, creating graphene field-effect transistors which can be activated by light. This may lead to the development of highly sensitive graphene-based optical devices, an advance that could bring applications from imaging and displays to sensors and high-speed communications.

GFETs show promise for optical technologies image

A typical problem of graphene-based photodetectors is that they have only a small area that is sensitive to light, limiting their performance. “In typical graphene-based photodetectors demonstrated so far, the photoresponse only comes from specific locations near graphene over an area much smaller than the device size,” the team said. “However, for many optoelectronic device applications, it is desirable to obtain photoresponse and positional sensitivity over a much larger area”. The researchers tackled exactly this in their new work.

Graphene Flagship team creates transistors printed with graphene and other layered materials

Apr 09, 2017

Graphene Flagship researchers from AMBER at Trinity College Dublin, in collaboration with scientists from TU Delft, Netherlands, have fabricated printed transistors consisting entirely of layered materials. The team's findings are said to have the potential to cheaply print a range of electronic devices from solar cells to LEDs and more.

The team used standard printing techniques to combine graphene flakes as the electrodes with other layered materials, tungsten diselenide and boron nitride as the channel and separator to form an all-printed, all-layered materials, working transistor.

The Graphene Flagship develops graphene-based neural probes

Mar 29, 2017

Researchers from the Graphene Flagship have developed a new graphene-based device able to record brain activity in high resolution while maintaining excellent signal to noise ratio (SNR). Based on graphene field-effect transistors, the flexible devices have to potential to open up new possibilities for the development of functional implants and interfaces.

Graphene-enabled neural probes by the Graphene Flagship image

Neural activity is detected through the electric fields generated when neurons fire. These fields are highly localized, so having ultra-small measuring devices that can be densely packed is important for accurate brain readings. The graphene-based probes are reportedly competitive with state-of-the-art platinum electrode arrays and have the benefits of intrinsic signal amplification and a better signal-to-noise performance when scaled down to very small sizes. This will allow for more densely packed and higher resolution probes, vital for precision mapping of brain activity. The inherent amplification property of the transistor also removes the need for a pre-amplification close to the probe – a requirement for metal electrodes.

Improved graphene-based transistors to detect disease-causing genes

Feb 26, 2017

Researchers in India and Japan have developed an improved method for using graphene-based transistors to detect disease-causing genes.

GFETs to detect harmful genes image

The team improved sensors that can detect genes through DNA hybridization, which occurs when a 'probe DNA' combines with its complementary 'target DNA.' Electrical conduction changes in the transistor when hybridization occurs. The improvement was done by attaching the probe DNA to the transistor through a drying process. This eliminated the need for a costly and time-consuming addition of 'linker' nucleotide sequences, which have been commonly used to attach probes to transistors.

Graphenea, Nokia and IEMN-CNRS collaborate to create high-frequency graphene transistors on flexible substrates

Feb 21, 2017

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.

Graphenea and Nokia create impressive GFET image

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%.