Nitrides for the 21st century
Lead Research Organisation:
University of Cambridge
Department Name: Materials Science & Metallurgy
Abstract
Our research has the potential to save millions of lives, save energy, save carbon emissions and enable totally secure communications. It is based on gallium nitride, which is probably the most important new semiconductor since silicon. Unlike silicon, gallium nitride emits brilliant light when a small electric current is passed through it. We can produce light of any colour (for example blue, green, yellow, red) by adding more and more indium to gallium nitride. On the other hand, if we add aluminium to gallium nitride we can produce ultra-violet light. Gallium nitride based light emitting diodes (LEDs) and laser diodes are already in widespread use, for example as LED traffic lights and as Blu-ray laser diodes for the latest DVD players. If we coat a blue LED with a yellow-emitting phosphor then a cool white light is produced, and such white LEDs are used as front bicycle lights, flashlights, backlighting for mobile phones, etc,The aim of this Platform Grant is to underpin our research in a number of key areas. Gallium nitride produces light so efficiently that if we could use white gallium nitride based LEDs for home and office lighting we could save 15% of all electricity used, reduce carbon emissions from power stations by 15% and close eight large power stations. However, high-power white LEDs are too expensive for home and office lighting, and the quality of the white light is too poor to be acceptable. Gallium nitride based LEDs are currently grown on two-inch diameter sapphire wafers. We are developing their growth on six-inch silicon wafers. If successful, this will reduce the cost of each LED by a factor of ten, which will make white LEDs cheap enough for home and office lighting. Some challenging new science in required for this, but we are world leading in this research. We are also planning to produce high quality white light, like natural sunlight, by developing new green and red phosphors, and we will tailor the wavelength of our LEDs to maximise the excitation of these new phosphors. We also plan to eliminate phosphors totally, which will further improve the efficiency, and produce white light by mixing blue, green, yellow and red LEDs. Currently green and yellow LEDs have relatively poor efficiency, for reasons which are not totally clear, and we plan to solve this problem. Solving both the problems of cost and quality will yield low-cost high-efficiency high-quality lighting for our homes and offices, with the substantial energy and carbon savings referred to above.Deep ultra-violet radiation stops bacteria and viruses from reproducing and hence essentially kills them. Aluminium gallium nitride LEDs at present emit in the deep-UV, but their efficiency is too low to be useful. We propose to make highly-efficient LEDs emitting in the deep-UV. These could be used to purify drinking water in the developing world. Over one billion people in the world do not have access to drinkable water, and drinking impure water kills more people in the world than AIDS. Our research could lead to literally millions of lives being saved. The LEDs operate at typically 4 Volts and so can be powered by solar cells, ideal for the developing world. Additionally such deep-UV LEDs could be used in a flashlight to shine on hospital walls, floors and bedding to kill superbugs.We plan to develop a novel gallium nitride based light source called a single photon emitter, which emits a single photon on demand. This would be used for sending totally secure messages. For example a mobile phone, with a single photon emitter, could send a message to a cash machine for you to obtain money, with no possibility of anyone obtaining your bank details, PIN number, etc. Our research therefore promises substantial benefits to the health, wealth, wellbeing and security of our society.
Planned Impact
As agreed with EPSRC Impact Summary is not required
Publications
Amari H
(2011)
Accurate calibration for the quantification of the Al content in AlGaN epitaxial layers by energy-dispersive X-ray spectroscopy in a Transmission Electron Microscope
in Journal of Physics: Conference Series
Amari H
(2012)
Measurement of the Al content in AlGaN epitaxial layers by combined energy-dispersive X-ray and electron energy-loss spectroscopy in a transmission electron microscope
in physica status solidi c
Ashraf H
(2010)
Reduction of the dislocation density in HVPE-grown GaN epi-layers by an in situ SiNx treatment
in Journal of Crystal Growth
Badcock T
(2013)
Carrier Density Dependent Localization and Consequences for Efficiency Droop in InGaN/GaN Quantum Well Structures
in Japanese Journal of Applied Physics
Badcock T
(2012)
Exciton confinement in narrow non-polar InGaN/GaN quantum wells grown on r -plane sapphire
in physica status solidi (b)
Badcock T
(2011)
Properties of surface-pit related emission in a -plane InGaN/GaN quantum wells grown on r -plane sapphire
in physica status solidi c
Badcock T
(2014)
Low temperature carrier redistribution dynamics in InGaN/GaN quantum wells
in Journal of Applied Physics
Badcock T
(2011)
Modification of carrier localization in basal-plane stacking faults: The effect of Si-doping in a -plane GaN
in physica status solidi (b)
Badcock T
(2010)
Effect of overgrowth conditions on the optical properties of lateral epitaxially overgrown a -plane GaN
in physica status solidi c
Badcock T
(2011)
The effect of indium concentration on the optical properties of a -plane InGaN/GaN quantum wells grown on r -plane sapphire substrates
in physica status solidi (a)
Badcock T
(2014)
Dynamics of carrier redistribution processes in InGaN/GaN quantum well structures
in physica status solidi c
Badcock T
(2013)
Evidence for Dark States in the Temperature Dependent Recombination Dynamics of InGaN/GaN Quantum Wells
in Japanese Journal of Applied Physics
Badcock T
(2009)
Optical polarisation anisotropy in a -plane GaN/AlGaN multiple quantum well structures
in physica status solidi c
Badcock T
(2012)
Recombination mechanisms in heteroepitaxial non-polar InGaN/GaN quantum wells
in Journal of Applied Physics
Badcock T
(2010)
Carrier dynamics in non-polar GaN/AlGaN quantum wells intersected by basal-plane stacking faults
in physica status solidi c
Badcock T
(2011)
The Effect of Dislocation Density and Surface Morphology on the Optical Properties of InGaN/GaN Quantum Wells Grown on r-Plane Sapphire Substrates
in Japanese Journal of Applied Physics
Badcock T
(2010)
Characterising the degree of polarisation anisotropy in an a -plane GaN film
in physica status solidi c
Barnard J
(2010)
The role of rough surfaces in quantitative ADF imaging of gallium nitride-based materials
in Journal of Physics: Conference Series
Bennett S
(2010)
Atom probe extended to AlGaN: three-dimensional imaging of a Mg-doped AlGaN/GaN superlattice
in physica status solidi c
Bennett S
(2009)
Atom Probe Tomography Studies of GaN-Based Semiconductor Materials
in Microscopy and Microanalysis
Bennett S
(2011)
Atom probe tomography assessment of the impact of electron beam exposure on InxGa1-xN/GaN quantum wells
in Applied Physics Letters
Bennett S
(2012)
Atom probe tomography characterisation of a laser diode structure grown by molecular beam epitaxy
in Journal of Applied Physics
Bennett S
(2010)
Mg dopant distribution in an AlGaN/GaN p-type superlattice assessed using atom probe tomography, TEM and SIMS
in Journal of Physics: Conference Series
Bennett SE
(2011)
Atom probe tomography and transmission electron microscopy of a Mg-doped AlGaN/GaN superlattice.
in Ultramicroscopy
Bennett SE
(2010)
Imaging dislocations in gallium nitride across broad areas using atomic force microscopy.
in The Review of scientific instruments
| Description | We have developed a new low-cost way of growing gallium nitride on 6-inch diameter silicon which will substantially reduce the cost of energy-efficient LED lighting. This was highlighted by the then science minister, David Willetts, in his report "Eight Great Technologies", published in 2013. We filed two patents on our work, in 2011 and in 2013 . Both have been granted. The UK company Plessey acquired our technology in 2012 and are now manufacturing such GaN LEDs, based on our technology, at their factory in Plymouth. This is the first ever manufacturing of GaN LEDs in the UK and the first commercially available GaN LEDs on silicon in the world. In 2014, Plessey sold over 2 million LEDs based on our technology. All other commercial white LEDs are grown on small-diameter sapphire or SiC substrates, which are expensive. Our low-cost high-efficient LEDs grown on large-area (150 mm diameter) silicon should enable their widespread use in home and office lighting, which will save the UK 10% of electricity, a saving of £2 billion per year. It will also save 10% of carbon emissions from power stations. In September 2015, Plessey raised £30 million from the Deutsche Bank and £30 million from other investors to enable them to expand their production. They are currently employing over 100 people in Plymouth manufacturing our LEDs. So our EPSRC funded research is generating manufacturing jobs and wealth in the UK. Our research has had impact across the LED supply chain. We have helped Aixtron (factories in the UK and Germany) to sell their growth reactors by advising them on their future requirements. We helped the UK SME Forge Europa (manufacturing in Ulverston, Cumbria) to solve a major problem they were having with the reliability of some LEDs which were being incorporated into their products. February 2019 addition. Plessey continue to manufacture LEDs in Plymouth, Devon. Their latest products, launched in 2018, are microLEDs. Each microLED is as small as 1 micron. This is the smallest in the world. This world-leading product is based on the GaN-on-Silicon technology developed in this grant, which Plessey acquired. It gives Plessey a competitive advantage in microLEDs. Such microLEDs are exceptionally bright and may be used in next-generation smart watches, smart phones, TVs, etc. A display screen made from microLEDs is visible in bright sunlight. March 2020 addition. Plessey has made significant advances with its microLEDs based on the GaN-on-silicon technology developed on this grant. Last year it had achieved blue and green emission. In the last 12 months it has achieved red emission. These are the world's first GaN-on-silicon red LEDs, and Plessey issued a press release in December 2019 about this. So Plessey now has blue, green and red micro LEDs for displays. This is a disruptive, game-changing technology for the next generation of Augmented Reality (AR) head-mounted displays, sports watches, mobile phone screens, etc. The displays are so bright they can be seen in bright sunlight, and their power consumption is very low. They are poised to replace LCD and OLED displays, since they are much brighter and have lower power consumption. In 2019, Plessey partnered with Vuzix, a leading supplier of smart glasses and AR, and Plessey is now licencing the technology to partners to manufacture on a commercial scale, to make a mass market product. This is all based on the work funded through this award. Added in March 2021. In 2020, Facebook chose Plessey as a partner for its microLED displays for AR, etc. A joint press release was issued. This is a huge achievement for Plessey. Again, all based on the research funded through this award. |
| Exploitation Route | The UK company Plessey has already commercialized our research, as outlined above. Aixtron (UK and Germany) have already acknowledged our help to them in achieving many £millions of sales. Forge Europa (Cumbria) acknowledges our help in solving a major LED reliability problem they had. See above. Humphreys spun-out two companies, CamGaN and Intellec, to exploit the GaN-on-silicon LEDs developed on this grant. These companies were then acquired by Plessey, which manufactured these LEDs and is now focussing its work on microLEDs based on our technology, as described above. Plessey is manufacturing in the UK, in Plymouth. |
| Sectors | Aerospace, Defence and Marine,Chemicals,Construction,Creative Economy,Digital/Communication/Information Technologies (including Software),Education,Electronics,Energy,Environment,Healthcare,Leisure Activities, including Sports, Recreation and Tourism,Manufacturing, including Industrial Biotechology,Transport |
| URL | http://www.gan.msm.cam.ac.uk |
| Description | The overall economic and societal impact of the research has been substantial. First, there is the direct exploitation of our research in the UK by Plessey. This is detailed below in the "Key Findings" section. Let me give some additional information. One of the PDRAs employed on this grant, David Wallis, led a team of three of my PDRAs (Plessey employed them all) in transferring to Plessey in 2012 the GaN LEDs on large area Silicon technology developed on this grant and on earlier EPSRC grants. This team of three of my PDRAs transferred this technology from my university GaN growth system to the Plessey commercial-scale growth system in only eight weeks (we had been told that it would take at least two years!). This has resulted in the world first of Plessey being the first company in the world to have GaN-on-Si LEDs commercially available, in 2013. In 2014 they sold over 2 million such LEDs. They are employing over 100 people to do this in the unemployment blackspot of Plymouth. I believe this is a great good news story for the EPSRC! We have also substantially helped the company Aixtron to increase its sales and Forge Europa to solve a key LED reliability problem, as mentioned in the "Key Findings" section below. We have performed all this exploitation work while performing world-class basic research on GaN based materials and devices, as evidenced by our large number of well-cited publications and also invited talks at international conferences. Second, we have spent a huge amount of time promoting the importance of GaN LEDs for saving energy and carbon emissions. We have given public lectures, schools talks, advised local councils, had meetings at BIS, spoken many times with the then Science Minister, David Willetts, and had two meetings with the then Prime Minister, David Cameron at Number 10. We believe that this has all helped the UK to start to change its lighting in homes, offices and streets to LED lighting. This change is accelerating and in the next 5-10 years I confidently expect GaN LED lighting to become the dominant form of lighting in the UK. When this happens, the UK will save 10% of all electricity use, 10% of carbon emissions from power stations and over £2 billion per year in electricity costs. In addition, we would not need to build about 10 new power stations. Consumers fitting LED lighting will save on their electricity bills, and save on replacing light bulbs because LEDs are so long lasting. LED lighting is increasingly being used in all new buildings because of the energy savings. Hence the construction industry is also being influenced. These are major economic and societal benefits that our EPSRC-funded research has helped to enable. February 2019 update. I believe it is now totally clear that GaN LED lighting will become the dominant form of home and office lighting in the world. For example, many supermarkets only sell LED light bulbs, all of them are made from GaN. Plessey continues to manufacture LEDs in the UK, at Plymouth, its latest products being microLEDs, based on our GaN-on-silicon technology, which are world leading (see below). Plessey sells LED chips to other companies to use in light bulbs, etc., and they are used in many sectors, listed below. A few months before the end of this grant Humphreys started discussions with an Indian student, Priti Gupta, about coming to Cambridge to work on GaN/graphene devices. Further information will be given in my report on the next grant, Lighting the Future. March 2020 update. MicroLEDs are a fast-emerging display technology because they are extremely bright and can be seen bright daylight, a problem with existing displays in sports watches and mobile phone screens. Existing microLEDs use a pick-and-place technology in which individual microLEDs are assembled into a display one-by-one. This slow process is not viable for manufacturing. The Plessey process, based on the GaN-on-silicon LEDs developed on this grant, overcomes this problem by using monolithic microLED multiple emitters on a single chip. This is the only monolithic microLED solution in the world, and it is based on the science and technology funded on this EPSRC grant. In the last 12 months Plessey have partnered with other companies to make a mass-market product. The date our GaN-on-silicon LEDs were first manufactured by Plessey was in 2014, as given below. The date the microLEDs were first materialised was 2019/2020. |
| First Year Of Impact | 2014 |
| Sector | Aerospace, Defence and Marine,Chemicals,Construction,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Environment,Leisure Activities, including Sports, Recreation and Tourism,Manufacturing, including Industrial Biotechology,Culture, Heritage, Museums and Collections,Retail,Transport |
| Impact Types | Societal,Economic |
| Description | Beyond Blue:New Horizons in Nitrides (Platform Grant Renewal) |
| Amount | £979,288 (GBP) |
| Funding ID | EP/M010627/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2015 |
| End | 01/2020 |
| Description | Free-standing wurtzite AlGaN substrates for DUV devices |
| Amount | £688,438 (GBP) |
| Funding ID | EP/K008323/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 08/2013 |
| End | 01/2017 |
| Description | Programme Grant: Lighting the Future |
| Amount | £6,361,650 (GBP) |
| Funding ID | EP/I012591/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 12/2010 |
| End | 11/2015 |
| Description | Sharp Laboratories Of Europe Ltd |
| Amount | £27,000 (GBP) |
| Funding ID | RG50526 |
| Organisation | Sharp Laboratories of Europe Ltd |
| Sector | Private |
| Country | United Kingdom |
| Start | 11/2006 |
| End | 09/2010 |
| Description | Silicon compatible GaN Power Electronics (Programme Grant) |
| Amount | £6,196,718 (GBP) |
| Funding ID | EP/K014471/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 03/2013 |
| End | 02/2018 |
| Description | Study of semi-polar and non-polar nitride based structures |
| Amount | £560,766 (GBP) |
| Funding ID | EP/J003603/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2012 |
| End | 12/2014 |
| Title | GaN LEDs on silicon |
| Description | This is a new low-cost method for growing GaN LEDs |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2012 |
| Provided To Others? | Yes |
| Impact | Plessey is manufacturing LEDs in the UK based on our technology |
| Description | Aixtron |
| Organisation | Aixtron Limited |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | We grew world class GaN device structures on our Aixtron reactor(s), thus increasing Aixtron sales. |
| Collaborator Contribution | They donated to us a senior scientist for 25% of his time. They provided free servicing and maintenance of our growth reactor. |
| Impact | Increased sales of Aixtron growth reactors. |
| Description | Forge Europa (International Headquarters |
| Organisation | Forge Europa |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Expertise. Solving a major problem with the reliability of some Forge Europa LEDs |
| Collaborator Contribution | Advice. Testing. Market forecasts. |
| Impact | Improved reliability and lifetimes of Forge Europa LED based products. |
| Description | Plessey collaboration |
| Organisation | Plessey Semiconductors Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | We developed a new low-cost high-efficiency method for making GaN LEDs. we set up two companies which Plessey acquired. Plessey also hired 3 of my post-docs to transfer the technology and as permanent hirings. We continue to collaborate with Plessey, providing them with advice. We also provided them with two growers for a period of three months when their main grower left in 2016. |
| Collaborator Contribution | Plessey process LED structures that we grow and we exchange information. The processing of our wafers is very important for our research. |
| Impact | Plessey are manufacturing GaN-on-Si LEDs at Plymouth based on our technology. This is the first and only manufacturing of GaN LEDs in the UK. Plessey had the first commercially available GaN LEDs on large area Si in the world, based on our Cambridge technology, funded by the EPSRC. Plessey raised £30 million from the Deutsche Bank and £30 million from other investors in 2015 to expand their GaN-on-Si LED manufacturing. The are employing over 100 people in Plymouth in LED manufacturing. They are manufacturing millions of LEDs per year. Materials Science, Physics, Chemistry, Electronics. |
| Start Year | 2010 |
| Description | Thomas Swan Scientific Equipment Ltd |
| Organisation | Thomas Swan and Co Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | The collaboration ceased when Thomas Swan Scientific Equipment was taken over by Aixtron, and we then collaborated with Aixtron. |
| Collaborator Contribution | Thomas Swan donated us a growth reactor in 2000. |
| Impact | Many publications which showed the excellence of the Thomas Swan growth reactor. |
| Title | SEMICONDUCTOR MATERIAL |
| Description | The present invention relates to a semiconductor wafer comprising: a substrate; a first Al Ga N layer on the substrate; a second Al Ga N layer on the first Al Ga N layer; a Ga N layer on the second Al Ga N layer; and a plurality of crystalline Ga N islands between the first and second Al Ga N layers. |
| IP Reference | WO2014053831 |
| Protection | Patent application published |
| Year Protection Granted | 2014 |
| Licensed | Commercial In Confidence |
| Impact | This development will reinforce the GaN-on-Si technology developed in Cambridge centre for GaN, which provides an alternative way to achieve high performance GaN-on-Si LEDs. Commercial exploitation of this discovery is under discussion. |
| Title | SEMICONDUCTOR WAFER COMPRISING GALLIUM NITRIDE LAYER HAVING ONE OR MORE SILICON NITRIDE INTERLAYER THEREIN |
| Description | The present invention provides a semiconductor wafer comprising: a substrate layer; and a first GaN layer having one or more SiNx interlayers therein; and wherein in the first GaN layer at least one SiNx interlayer has GaN penetrated through one or more portions of said SiNx interlayer and preferably has a thickness of from 0.5 to 10nm. |
| IP Reference | WO2012066269 |
| Protection | Patent granted |
| Year Protection Granted | 2012 |
| Licensed | Yes |
| Impact | This patent was transferred to a Cambridge spin-out, CamGaN Ltd, for commercial exploitation of the technology described in the patent. CamGaN was later acquired by Plessey semiconductors in 2012. A portfolio of products based on the CamGaN technology has been launched by Plessey and has generated positive market feedback. |
| Company Name | CamGaN |
| Description | Set up to exploit GAN LEDs on 6 inch Silicon. |
| Year Established | 2010 |
| Impact | CamGaN was formed in 2010 to commercialise a novel technology (GaN LEDs on large-area (150 mm diameter) silicon) for the cost-effective manufacture of key components of high-brightness LEDs. This novel technology holds strong potential to dramatically reduce the cost of solid-state lighting devices that are rapidly replacing incandescent and fluorescent light bulbs. Plessey acquired CamGaN in 2012. In 2014 they manufactured over 2 million LEDS based on this technology. Recently they have raised £60m to expand production capacity and this will employ 400 more people in Plymouth. The widespread use of LED lighting in the UK will save 10% of all our electricity used and 10% of carbon emissions from power stations. We are continuing to develop this work on current EPSRC grants. See also my entry under my spin-out company Intellec. |
| Website | http://www.enterprise.cam.ac.uk/news/cambridge-spin-out-camgan-acquired-by-plessey/ |
| Company Name | INTELLEC LTD |
| Description | To further exploit our low-cost GaN LEDs on large area silicon. |
| Year Established | 2011 |
| Impact | Intellec and CamGaN were taken over by Plessey in 2012. Plessey are now manufacturing millions of LEDs each year based on our technology. They are manufacturing in the UK, in Plymouth. Over 100 people are employed by Plessey in the UK on manufacturing our LEDs. Plessey raised £30 million from Deutsche Bank and £30 million from other investors in September 2015 to expand their manufacturing capabilities. Humphreys is a member of the Plessey Advisory Board. We continue to work with them on a variety of EPSRC grants. See also the entry under my spin-out company CamGaN. |
| Website | http://www.endole.co.uk/profile/15411715/colin-john-humphreys |
| Description | BBC Breakfast TV and BBC Radio "You and Yours" |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | Interview of Prof Humphreys on BBC Breakfast TV, and on the BBC Radio "You and Yours" on low-cost LEDS sparked a lot of discussions Increased public awareness of LEDs |
| Year(s) Of Engagement Activity | 2009 |
| Description | Big Bang Fair (London) |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | Yes |
| Geographic Reach | National |
| Primary Audience | Schools |
| Results and Impact | Encouraged school pupils to study science Schools reported increased interest in science and increased numbers studying science |
| Year(s) Of Engagement Activity | 2013,2014 |
| Description | Chelterham Science Festival |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | Yes |
| Geographic Reach | National |
| Primary Audience | Schools |
| Results and Impact | More school pupils studying science Schools reported greater interest in science. |
| Year(s) Of Engagement Activity | 2013,2014 |
| Description | Talk to visiting school group (Communications using light) |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Schools |
| Results and Impact | An interactive talk on "Communication using Light" was delivered to a group of sixth formers visiting the department, incorporating elements on LiFi using LEDs and quantum communication using single photon sources. |
| Year(s) Of Engagement Activity | 2016 |