EPSRC Manufacturing Fellowship in Gallium Nitride

Lead Research Organisation: CARDIFF UNIVERSITY
Department Name: Sch of Engineering

Abstract

Gallium Nitride (GaN) based optoelectronic devices have the potential to revolutionise our society. They are more efficient and more robust than the alternative device technologies used today and therefore last longer and deliver significant energy savings. For example, GaN LEDs can be used to replace compact fluorescent and incandescent light bulbs in our homes and places of work. Such LED light bulbs have the potential to reduce by up to 50% the energy we use for lighting. Since about 20% of all the electricity we generate is used for lighting applications this would save the equivalent of about 8 power stations worth of electricity in the UK each year. Another, potentially even larger area where Gallium Nitride could have a significant impact is power electronics. Power electronic devices are found in electric cars, power supplies for laptop, and the control systems for mains electricity. Since GaN power electronics can handle more power, operate at higher voltages and are again significantly more efficient than other semiconductor technologies, it is estimated that by switching to GaN power electronics it may be possible to save up to £1 trillion each year in global energy costs.

From these examples it is clear that GaN devices can significantly help to reduce our demand for energy and therefore our Carbon footprint. However, for this potential to be realised, research still needs to be done to deliver the promised performance of these devices and to reduce their manufacturing cost so that they are widely accepted.

Production of semiconductor devices involves the manufacture of thousands or even millions of devices simultaneously on a circular wafer. One of the developments which has allowed the low cost and pervasive nature of Silicon electronics today are the economies of scale that can be achieved when large diameter wafer are used. A key step therefore in the manufacturing of low cost GaN devices is the development of high quality GaN layers grown onto large diameter Silicon wafers. This will allow the high volume production techniques that have been developed for the Silicon electronics industry to be applied for GaN devices reducing their cost by up to 80%.

Research carried out in this fellowship will provide new knowledge about how to grow and control GaN device layers. This will allow the promise of these devices to be realised enabling higher efficiencies, new applications and growth on large diameter Silicon substrates (upto 200mm). By carrying out this research in close collaboration with UK industry, the developments will be focused towards real products and address some of the real world challenges associated with delivering high performance and reliable devices. This will also ensure that the research supports the developing GaN device manufacturing base in the UK and can contribute to the commercial exploitation of GaN technology.

Planned Impact

Gallium Nitride (GaN) devices have the potential to address some of the major challenges currently facing society. The high efficiency with which GaN can convert electrical energy in to light and control electrical energy means that such devices can reduce electricity consumption by 10's of percent, contributing to reduced carbon emissions and saving billions of pounds. Thus the research to be carried out in this fellowship will contribute to many of the Government led initiatives in the UK and across the world aimed at reduced energy usage, improved energy security and reduced green house gas emission. By contributing to the delivery of efficient GaN devices, the outputs of this research will tackle these goals and have an impact on how policy makers plan to address issues such as the integration of renewable energy sources and delivery of environmentally friendly transport policies.
There are a significant number of companies in the UK currently developing products based on GaN. For example Plessey, NXP, International Rectifier and IQE(Europe) are all actively developing GaN technologies. Through my links to these industries the improvements in GaN materials technology delivered by this fellowship will be rapidly available for incorporation in to future and existing projects allowing results to be exploited on very short timescales, i.e. less than 1 year in some cases. Additionally, there are a number of supply industries which support these manufacturing capabilities such a Laytec UK who produce in-situ growth monitoring systems, Aixtron UK who manufacture MOCVD growth systems and Oxford Instruments who build GaN processing tools. I already have established links with many of these commercial organisations as a result of my current research activates. This fellowship will provide opportunities to strengthen and widen these interactions, contributing to the whole GaN technology supply chain in the UK. Existing interactions with these industries include both collaborative development projects and testing of measurement systems in a manufacturing environment. Close links with these commercial activities are important for the delivery of devices compatible with real world applications since many of the manufacturing and reliability issues can only be addressed by performing trials in a volume production environment with the highly reproducible processes that this delivers. Here my intimate knowledge of the volume production facilities at Plessey and future access to these offer a unique opportunity to bridge the gap between research and manufacturing.
Apart from companies involved directly with GaN materials and devices there are also a large number of organisations developing system level products based on GaN technologies. These include >100 companies developing lighting products (Luminaires) based on GaN LEDs. The Cambridge centre for GaN already has links and provides advice to some of these companies, for example Forge Europa, and along with my own contacts, this fellowship position within the University will provide me with more freedom to interact with these organisations without the limitations of specific commercial interests.

Through the delivery of more efficient lighting and power systems and contributing to the delivery of government policy, this fellowship will also have an impact on the general population both in the UK and globally. This will be seen through improved quality of life enabled by the tackling of climate change and reduction of fuel poverty. A direct benefit to the population of the UK will be seen through reduced energy bills as more efficient lighting and power control systems are made available in our homes and businesses. It is possible that such benefits could begin to be seen within the 5 year period of this fellowship as the commercial take up of GaN devices accelerates.

Publications

10 25 50
 
Description The research funded on this grant has allowed development of the growth and Characterisation of GaN-based device structures. Key findings are in two areas; firstly in the area of GaN high power electronic devices which offer higher frequency, higher power and higher efficiency operation compared to conventional device technologies. The second area is in the growth of cubic-GaN. This has the potential to overcome some of the challenges with conventional GaN LEDs and will allow higher efficiency green LEDs to be developed to give better displays and LED light bulbs
Exploitation Route The cubic phase of GaN is not as well understood as the standard hexagonal phase. The process that has been developed to grow high quality cubic GaN films has already allowed new collaborations to be established with the universities of Manchester and Strathclyde to study this material. Along side this a spin-out company called Kubos Semiconductors has been formed to commercially exploit the technology to develop efficient green LEDs
Sectors Digital/Communication/Information Technologies (including Software)

Electronics

Energy

 
Description Research carried out in to the growth of the cubic form of Gallium Nitride (GaN) has lead to the formation of a spin out company, Kubos Semiconductors Ltd. Kubos will take forward the exploitation of the cubic GaN technology to allow commercial benefit to be realized from the production of efficient green LEDs. In 2024 Kubos continues to develop cubic GaN technology and is now targeting the microLED displays market where cubic GaN has the potential to significantly improve display performance. Kubos has raised more than £2.5M in private funding and has plans to employ a further 4 people based on the latest investment round.
First Year Of Impact 2017
Sector Digital/Communication/Information Technologies (including Software),Electronics,Energy
Impact Types Economic

 
Description DCMS visit to South Wales Semiconductor Cluster
Geographic Reach National 
Policy Influence Type Contribution to a national consultation/review
Impact The input provided contributed to the development of the UK semiconductor strategy published in May 2023
 
Description EPSRC Platform grant
Amount £4,325,358 (GBP)
Funding ID EP/P00945X/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 01/2017 
End 12/2021
 
Description EPSRC responsive mode funding
Amount £988,856 (GBP)
Funding ID EP/R010250/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 02/2018 
End 01/2021
 
Description Fast Switching Zincblende GaN LEDs
Amount £473,432 (GBP)
Funding ID EP/W034956/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 12/2022 
End 11/2025
 
Description The Energy Entrepreneurs Fund
Amount £483,000 (GBP)
Funding ID EEF6084 
Organisation Department for Business, Energy & Industrial Strategy 
Sector Public
Country United Kingdom
Start 09/2018 
End 09/2020
 
Title Data supporting review paper on cubic GaN 
Description Previously unreported data included in the review paper entitled " Cubic GaN and InGaN / GaN Quantum wells" corresponding to Figure 1 and 5 of that paper. Figure 1 shows the emission wavelengths for quantum well widths between 2 and 10 nm. Figure 5 compares the photoluminescence spectra from epilayers of hexagonal and cubic GaN. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://figshare.manchester.ac.uk/articles/dataset/Data_supporting_review_paper_on_cubic_GaN/1961447...
 
Title Data supporting review paper on cubic GaN 
Description Previously unreported data included in the review paper entitled " Cubic GaN and InGaN / GaN Quantum wells" corresponding to Figure 1 and 5 of that paper. Figure 1 shows the emission wavelengths for quantum well widths between 2 and 10 nm. Figure 5 compares the photoluminescence spectra from epilayers of hexagonal and cubic GaN. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://figshare.manchester.ac.uk/articles/dataset/Data_supporting_review_paper_on_cubic_GaN/1961447...
 
Title Dataset - the effect of thermal annealing on the optical properties of Mg-doped zincblende GaN epilayers.xlsx 
Description Data contained in the file are from time integrated and time resolved photoluminescence spectroscopy and X-ray diffraction measurements that characterise the effect of thermal annealing on the optical properties of Mg-doped zincblende GaN epilayers. For more information, including methodology, see article. 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
URL https://figshare.manchester.ac.uk/articles/dataset/Dataset_-_the_effect_of_thermal_annealing_on_the_...
 
Title Dataset - the effect of thermal annealing on the optical properties of Mg-doped zincblende GaN epilayers.xlsx 
Description Data contained in the file are from time integrated and time resolved photoluminescence spectroscopy and X-ray diffraction measurements that characterise the effect of thermal annealing on the optical properties of Mg-doped zincblende GaN epilayers. For more information, including methodology, see article. 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
URL https://figshare.manchester.ac.uk/articles/dataset/Dataset_-_the_effect_of_thermal_annealing_on_the_...
 
Title Research data supporting "Defect structures in (001) zincblende GaN/3C-SiC nucleation layers" 
Description The data file "facet angle AFM" contains the full datasets of facet angles measured by AFM of a nominally 3 nm-thick annealed GaN NL grown on 3C-SiC. The individual islands have been approached by front of the AFM tip along the fast scan direction, which was along [110] (along the short axis of the islands). Linescans have been taken parallel to fast scan direction in direction of the approaching tip. Angles have been measured between the facets and the surrounding surface. To determine the facet angle of the other site of the islands, the sample has been rotated by 180° prior to another AFM measurement. 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
URL https://www.repository.cam.ac.uk/handle/1810/321510
 
Title Research data supporting "Investigation of wurtzite formation in MOVPE-grown zincblende GaN epilayers on AlxGa1-xN nucleation layers" 
Description The data consists of Scanning transmission electron microscopy based Energy-dispersive X-ray spectroscopy measurements. Data consists of the information from the Line profile obtained across the AlGaN (x=0.29) nucleation layer for different elements such as Si Ka, Pt Ma, Ga La, Al Ka. The second file (dm3 file) is a cross-sectional HRTEM image (zone axis = [110]) of the zb-GaN epilayer on GaN NL grown over 3C-SiC, shown in figure 1 of the associated publication (https://doi.org/10.1063/5.0077186). 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://www.repository.cam.ac.uk/handle/1810/337300
 
Title Research data supporting [Design of step-graded AlGaN buffers for GaN-on-Si heterostructures grown by MOCVD] 
Description The dataset includes all the data used for the quantitative analysis in the associated article. The sample numbers are the same as in the article, and all the quantities have the same units that are used in the article (e.g., GPa for stress, µm for thickness, arc-secs for HRXRD FWHMs etc.). In particular, the stress-thickness (abbreviated 'St_thick', 'ST', or 'Stress_thick' in the column header) versus thickness (abbreviated 'Thick' or 'Layer_Thick') data for each layer includes both experimentally collected data (abbreviated 'Expt') and fitted data (abbreviated 'Fit'). The data for the AlN, the complete AlGaN buffers, and the GaN layers for each wafer are tabulated in separate files. All the other files include only experimental data from the measurements described in the article. 
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://www.repository.cam.ac.uk/handle/1810/345095
 
Title Quantum Wires in Cubic group III Nitrides 
Description GaN-related structures in the cubic/zincblende phase are known as a promising alternative to the more widely-known wurtzite/hexagonal GaN semiconductors, and may be used to achieve improved efficiencies for long-wavelength (including Green amber and red) LEDs. Semiconductors, such as those comprising GaN, are known to give rise to photo-luminescent and electro-luminescent properties, where such semiconductors may be used in LED or photo-diode devices. Group-Ill nitride semiconductors generally offer a wide range of optoelectronic applications including LEDs, and laser diodes emitting in the blue, green, and red spectral region. However, conventional LED sources still require separate polarisation filters when used in display technology, which inherently reduces the transmission of light, and thus reduces efficiency of the system. Thus, it would be advantageous to obtain a polarised light source for use in LD or LCD displays, or other such devices requiring a polarised light source. 
IP Reference PC928981GB 
Protection Patent / Patent application
Year Protection Granted 2019
Licensed Yes
Impact This patent application has been licenced to a spin-out company called Kubos Semiconductors Ltd. kubos is currently futher developing this technology and IP to allow commercial exploitation.
 
Title ZINCBLENDE STRUCTURE GROUP III-NITRIDE 
Description A process to grow cubic Gallium Nitride (GaN) stuctures compatible with producing devices such as LEDs and LASERS 
IP Reference Singapore (SG) Patent No: 11201908884Q 
Protection Patent / Patent application
Year Protection Granted 2021
Licensed Yes
Impact This patent application has lead to the formation of a spin-out company called Kubos Semiconductors limited. To date this company has 3 employees and has raised >£1.4M in private capital. Kubos is engaged with several multinational companies to further develop this technology
 
Company Name Kubos Semiconductors 
Description Kubos Semiconductors commercialises and develops technology designed to produce efficient, affordable LEDs, based on IP from Anvil Semicoductors Ltd. 
Year Established 2017 
Impact Kubos Semiconductors Ltd has to date raised >£1.4M in private funds and has been awarded an Energy Entrepreneurs Fund grant of £490k to fund development of cubic GaN technology and develop its business
Website http://www.kubos-semi.com
 
Description Presentation at Manufacturing 2075 event at university of Cranfield 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Approx 40 school children attended the presentations and then participated in workshops to discuss manufacturing requirements for the future. This increased their awareness of STEM activities in Manufacturing and prompted them to consider how the manufacturing of future products could be improved
Year(s) Of Engagement Activity 2017
URL https://www.cranfield.ac.uk/events/manufacturing-2075-landing/manufacturing-2075--2017-virtual-sympo...
 
Description Public presentation for the school of physical sciences at university of Cardiff 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact This presentation was part of a series of talks which is intended to expose the research activities at the university of Cardiff to a broad audience
Year(s) Of Engagement Activity 2017