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.

Potential 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.