Startup Aims to Replace Indium with Graphene

Article By : Nitin Dahad

Paragraf intends to bring graphene-based sensors to market, and will explore replacing expensive indium with graphene in electronic displays.

UK startup Paragraf has raised £12.8 million ($16 million) to get its graphene-based sensors to market. It has also received a grant of £500K from government body UK Research and Innovation to explore using graphene to replace the rare metal indium in electronics devices.

Paragraf is focused on delivering large-area graphene on various substrates, enabling production of mass-market scale graphene devices. The latest funding will help it commercialize its first product, a high sensitivity magnetic field detector that it says operates over temperature, field and power ranges that no other device can currently achieve.

In addition to its commercial activity, the company also received a grant from the British government’s research funding body to work with Queen Mary University in a year-long project to develop next-generation graphene for the replacement of Indium. The rare metal is on the EU Critical Materials List and is said to have an irreplaceable role in industry and society. The main use of indium is in indium tin oxide (ITO), widely used in solar panels, mobile phones and TV screens, within the displays, LEDs, OLEDs and touch panels. More than 90% of the display market uses ITO. Indium phosphide (InP) and indium gallium nitride (InGaN) are also a useful semiconductors with applications in photonics.

More than two-thirds of the world’s scarce indium reserves are in China, however, which currently produces over half of the world’s supply.

ITO is widely used because of its combination of properties — high electrical conductivity, high transparency and ease of deposition. However, because of its scarcity it is expensive (£360 per kg. By comparison, zinc costs only £4 per kg). ITO costs even more, £1,700 per kg, five times the price of silver. The global demand for ITO is £2.6 billion per year and rising. There is therefore an urgent need to replace ITO with something more sustainable.

Graphene, a sheet of carbon just one atomic layer thick, also has a remarkable combination of properties: high electrical conductivity, high transparency and high flexibility. But since its isolation in 2004 in the form of small flakes, only a few mm across, graphene has not been used commercially in electronic devices because of the difficulty in scaling up its size to be large enough for manufacturing.

Paragraf 8-inch graphene

An 8-inch graphene wafer from Paragraf (Image: Queen Mary University London)

However, Paragraf, which spun out of a research group at the University of Cambridge, has started producing graphene at up to eight inches in diameter, using a new CVD process. In the normal CVD process, graphene is grown on copper. The copper-contaminated graphene then has to be removed from the copper and transferred onto the desired substrate. But this process meant it has not been viable as an ITO replacement. The proposed next-generation graphene can be grown directly on substrates such as silicon and is free from metallic contamination. Replacing ITO by graphene could hence be transformational.

Paragraf has entered a collaboration agreement with Queen Mary University of London (QMUL), which will perform the basic graphene research, to study and develop a wide range of graphene devices. Other UK companies are supporting the project by donating materials upon which Paragraf will deposit graphene: IQE will supply test structures of GaAs electronic devices; Plessey Semiconductor will supply GaN/InGaN LEDs. Verditek will supply silicon solar cells. In addition, QMUL will grow OLEDs on Paragraf graphene. Forge Europa will perform accelerated reliability tests on the devices.

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