Nanowires on graphene

CrayoNano has developed a novel technology that enables growth
of positioned and vertically aligned nanowires on graphene.

By growing AlGaN (aluminium gallium nitride) nanowires on graphene, graphene will be used both as a substrate and as a UV transparent electrode in order to achieve a high external efficiency.

CrayoNano’s unique device structure thus leads to reduced heat loss, and in addition reduced material consumption.

Nanowires enable improved crystal quality, which can improve operating lifetime, and reliability as reduced lifetime and reliability has been connected to high dislocation density in thin film devices. Dislocation density is the amount of structural failures in the crystal structure. Nanowire technology can also increase the effective area of the LED, relative to planar technology, increasing the amount of light generated.

The result is a flexible and extremely thin and lightweight epiwafer able to emit large amounts of light from a small area.

Graphene is experiencing tremendous attention worldwide. Semiconductor nanowires on graphene are expected to become the basis for new types of device systems, and ultimately change the semiconductor industry.

UVC LED Challenges and CrayoNano’s Solution

While traditional planar design has more issues with lattice mismatch that affects the crystal quality and efficiency,
AlGaN nanowires on graphene have high crystal quality and can accommodate strain without the formation of dislocations.

Today’s UVC LED solutions

CrayoNano’s solution

Transparent electrode and substrate issues

  • Traditional transparent top contacts like ITO cannot be used due to high amount of UVC light absorption. UVC LED suppliers are therefore emitting light through AlN or sapphire substrates.
  • AlN is very expensive, and needs extra process to thin the substrate.
  • Sapphire starts to absorb in UVC and needs a thick conductive AlN buffer.

Graphene as combined substrate and electrode

  • CrayoNano’s devices will be based on a unique method of growing AlGaN nanowires on graphene, where graphene will be used both as a substrate and a UVC transparent electrode in order to achieve a high external efficiency.
  • Graphene is transparent to all wavelengths, has a very low absorption and record high electrical and thermal conductivity that enable a high external efficiency.

Planar layered design

  • Traditional planar design has more issues with lattice mismatch that affects the crystal quality and efficiency.




Wall plug efficiency of commercially available UVC LEDs is therefore today only around 1-5%.

Nanowire based design

  • AlGaN nanowires on graphene have good crystal quality and can accommodate strain without the formation of dislocations.
  • Nanowires enables improved crystal quality, operating lifetime and reliability.


CrayoNano’s UVC LED technology has
the potential to achieve wall plug
efficiencies of 10-50% at a lowered cost
– similar to UVA LEDs.

The technology uses existing wafer fabrication processes and tools, enabling production of UVC LED chips with higher
efficiency at significantly lower cost, resulting in a reduced cost performance ratio [€/W] of a factor of >10 compared to current UVC technology.

Higher output - lower cost

The technology uses existing wafer fabrication processes and tools, enabling production of UVC LED chips with higher
efficiency at significantly lower cost, resulting in a reduced cost performance ratio [€/W] of a factor of >10 compared to current UVC technology.

Current UVC solutions

CrayoNano’s graphene UVC solution

Wall plug efficiency (WPE) =1–5 %

Technology enables a wall plug efficiency (WPE) = 10–50 %

100 mW of UVC output power needs about 3 W of electricity. 2.9 W is converted to heat.

100 mW UVC output power needs <1.2 W of electricity. Less than 1.1 W is converted to heat.

UVC LED companies are using expensive aluminum nitride (AlN) substrates or thick buffer layers.

A UVC LED made with CrayoNano technology with 2-3x efficiency improvement at one fourth of the cost of current planar UVC LEDs.

What is it with Graphene?

Graphene is a new high-tech material with several outstanding properties:

  • High transparency: Graphene is transparent to all wavelengths of light.
  • Record high conductivity: Higher conductivity than copper of similar thickness.
  • Flexible
  • Extremely thin and strong: Stronger than steel of similar thickness
  • Semiconductor substrate: Can be used as a substrate for growth of semiconductor nanowires

Graphene is not a semiconductor…
… but due to these unique properties, graphene is a new and novel semiconductor substrate that will enable radical new devices and applications.

CrayoNano has an extensive patent portfolio related to opto-electronic uses of graphene

Technical Resources and Publications

Our technology platform is protected through multiple patent families. Please find a list of technical articles on the underlying results here.