Graphene has to show maturity before CMOS integration, say panel at Photonics Europe

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Greg Blackman reports from a workshop on graphene commercialisation at SPIE Photonics Europe in Brussels 

Broadband light detectors, gas sensors and EUV pellicles could be among the first devices made from graphene, a panel of experts concluded during a workshop about the carbon-based 2D material at SPIE Photonics Europe in Brussels. The conference and exhibition took place from 4 to 7 April.

Integration in CMOS production lines, however, will take a number of years, Paul Hedges, CEO of Applied Nanolayers, warned during the discussion. He said that graphene has to be shown to be scalable in CMOS fabs, as well as being orders of magnitude higher performance than existing technology in order to make the material commercially viable.

Graphene in its purest form is a single layer of carbon atoms, and has material properties that make it desirable for numerous applications, from flexible electronics and batteries, to displays and photosensors. The European Commission has invested €1 billion into research on the material as part of its 10-year Graphene Flagship project. As yet, though, work on graphene remains mainly scientific, with large corporations not investing because it is yet to be proven in terms of industrial implementation.

There are more niche areas where graphene is showing promise, however. Applied Nanolayers, which grows wafer-scale graphene by chemical vapour deposition (CVD), is working on graphene pellicles for EUV lithography machines that Hedges said could be a commercial product within one and a half years.

Broadband detectors made from graphene for applications like hyperspectral imaging could be a reality within four years, according to Bjarke Jørgensen, head of research at Danish company Newtec, while Cedric Huyghebaert at Imec envisioned a similar timeframe for gas sensors.

Newtec, which manufactures machines for the food industry, is developing graphene-based gas sensors and broadband detectors for use in its systems.

Jørgensen commented that companies should be looking to develop niche applications in more of an open platform at the moment, since there is not much investment in graphene technology from large semiconductor firms. He drew a parallel with the Linux platform and its success, saying that a similar transparent way of conducting graphene research would open up the material to new applications.

Huyghebaert, who is team leader at Imec’s graphene group, commented that there needs to be some maturity in terms of integrating the technology into CMOS lines before 2D materials will start to become attractive.

Imec is ultimately working on monolithic CMOS graphene integration with other photonic applications stacked on top. Huyghebaert said that, at the moment, only far back end of line integration is possible, because the quality of today’s graphene doesn’t outperform existing technology by a significant amount.

Christoph Stampfer at RWTH Aachen University also commented that researchers should be looking at the broad spectrum of 2D materials, not just graphene, since if one 2D material can enter semiconductor foundries, then so will graphene.

Stampfer presented results from research into ultra-high mobility graphene devices made with chemical vapour deposition on reusable copper. He said the key to fabricating high quality graphene was the flatness of the substrate. The work at RWTH Aachen University used boron nitride stacks, which could be made extremely flat.

The other panellists taking part in the discussion were Stijn Goossens at ICFO, the Institute of Photonic Sciences located near Barcelona, Spain, and Daniel Neumaier at AMO, a non-profit SME that spun out of RWTH Aachen University.

Goossens has been working on a hybrid light detector made from graphene and colloidal quantum dots, along with flexible sensors for measuring heart rate, while AMO has been working on graphene for high frequency electronics, among other applications.

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Further information:

SPIE Photonics Europe