Growth of cubic gallium nitride on silicon wafers by MOCVD offers promise of lower cost, more efficient LEDs

Anvil Semiconductors and the Cambridge Centre for GaN at the University of Cambridge have successfully grown cubic GaN on 3C-SiC on silicon wafers by MOCVD. The underlying 3C-SiC layers were produced by Anvil using its patented stress relief IP that enables growth of device quality silicon carbide on 100mm diameter silicon wafers.  The process is readily migrated onto 150mm diameter wafers and potentially beyond without modification and is therefore suitable for large, industrial-scale applications.

The MOCVD growth trials at Cambridge, conducted under a project funded by Innovate UK, have resulted in single phase, cubic GaN.  The layers, characterised by XRD, TEM, photoluminescence and AFM, show promise for LED applications.

The availability of cubic GaN has the potential to remove the strong internal electric fields which plague conventional green LEDs and which impair recombination and make it difficult to address high internal quantum efficiency (IQE). Additionally, cubic GaN has a narrower bandgap and improved p-type electrical properties compared to the standard hexagonal GaN phase normally used for LEDs and therefore offers several advantages. The ability to produce cubic GaN from a readily commercialisable process on large diameter silicon wafers is clearly recognised as a key enabler for increasing the efficiency and reducing the cost of LED lighting.

The team intends to continue development to the point of fabricating sample LEDs before looking for an industry partner to help commercialise the technology.

Professor Sir Colin Humphreys, Professor and Director of Research, Department of Materials Science and Metallurgy commented: “This is a very promising development and fits well with our current research activities to develop state of the art LEDs. It has the potential to overcome many of the challenges currently seen for green devices and could contribute significantly to the ongoing solid state lighting revolution.”

Jill Shaw, CEO of Anvil Semiconductors added: “This is a very exciting result which potentially opens up the LED market for our 3C-SiC on silicon material. We will certainly be looking for partners to help us take this opportunity forward”.

About Anvil Semiconductors

Anvil Semiconductors which is backed by Business Angels and early stage VCs was established in August 2010 to develop unique silicon carbide power devices for the power electronics industry.

Power electronics and switches are used to switch and control power from AC line to DC conversion for applications as diverse as laptop computers or other consumer products to railway electric traction and the grid. In the modern world it is ubiquitous and plays a key role in improving the efficiency in energy utilisation of everyday products.

Anvil’s alternative approach to SiC switches offers significant improvements in efficiency whilst costing no more than their silicon competitors.  This approach involves growing a thin layer of 3 step cubic SiC (3C-SiC) on silicon substrates sufficient to build the active power devices.  In addition to the fundamental crystal growth expertise, Anvil has intellectual property (IP) relating to resolving the problem of the stress which is inevitable when growing SiC on silicon and which to date has prevented the widespread adoption of this technology.  The Anvil IP has been proven on 100mm diameter silicon wafers and can be readily migrated onto larger wafer diameters without modification.  More information on Anvil Semiconductors and its technology can be found at  www.anvil-semi.co.uk

About the Cambridge Centre for GaN

The Cambridge Centre for GaN, a world leading Group, is part of the Department of Materials Science and Metallurgy in the University of Cambridge and is led by Professor Sir Colin Humphreys. It has been actively involved in the development of GaN growth technologies for more than 15 years and is the leading group for GaN materials research in the UK. Through its current activities the Group supplies epitaxial layers to many groups involved in GaN research both in the UK and internationally. It has experience in the growth of GaN layers on to Sapphire, bulk SiC, bulk GaN and large area silicon substrates and in 2011 the intellectual property developed for GaN growth on silicon was acquired by Plessey Semiconductors, who are currently using this technology to manufacture LEDs commercially. The group has a range of EPSRC, EU and industrially funded programmes including a programme grant titled, “Lighting the Future”. This is focused on the development of LED structures in GaN and understanding the factors limiting their performance. The group also has projects developing GaN for a diverse range of applications, including electronics, lasers and single photon sources based around its state-of the art MOCVD growth reactors .