PLroomIt’s long been known that the unique properties of III-nitride semiconductor materials make them ideally suited to microelectronics and optoelectronics. But they also have a critical role to play in addressing some of the major global challenges through advances in energy efficient lighting, solar power generation, water purification and environmental protection.

One of these materials – Gallium Nitride (GaN) – offers a more efficient, thermally and chemically stable alternative to silicon and other compound semiconductors in both Photonics and Electronics, however, achieving the crystal quality, scalability and cost effectiveness of GaN is key to bridging the gap between fundamental research and large-scale manufacturing. Over the last 10 years the Centre for GaN Materials and Devices has developed a number of advanced MOVPE (Metalorganic vapour-phase epitaxy) overgrowth and novel nanofabrication techniques in order to address this manufacturing challenge.

Research activities within the Centre have applications that could directly address current climate change issues. These include:

Solid-state light sources

EL Emission photos of (a) green, (b) yellow-green, (c) yellow, and (d) amber LEDs, taken at 5, 20, and 100 mA.

Solid-state lighting (SSL) is a semiconductor technology that converts electricity into light with no energy loss. We’re already benefiting from the significant energy savings of LEDs and group III-nitrides are the only semiconductors that emit light efficiently at short wavelengths.

The Centre is looking to use semiconductors to create not only extremely efficient solid-state lighting sources but also digitalized applications – smart lighting and Light Fidelity (Li-Fi). Projects include Hybrid White Light Emitters (a combination of III-nitride based inorganic materials with organic semiconductors) and semi-polar LEDs for ultrafast visible light communications and opto-genetic applications.
Schematic illustration of our HEMT-LED device
Solar hydrogen generation by water splitting using an InGaN/GaN device

Solar cells and solar hydrogen generation

The chemical stability, high efficiency and widely tuneable bandgap of nitride materials make III-nitride semiconductors ideal for solar energy applications. This can be in the form of solar cells (electrical devices that convert the energy of light directly into electricity) or photoelectrodes for solar powered hydrogen generation (water splitting). Hydrogen is a potential renewable, low-carbon fuel source. Our advances in nanostructure fabrication enhance the conversion efficiency of a variety of photovoltaic and photoelectrode devices.

UV-LEDs

Optical sterilization using Ultra-violet (UV)-Light Emitting Diodes (LEDs) is a chemical-free, safe and cost-effective method of obtaining clean water. The harmful particulates in vehicle exhaust can be decomposed by using an optical catalyst under the illumination of UV LEDs. With a focus on the next generation of non-polar or semi-polar GaN the Centre’s research is paving the way for devices with the high response time needed for emerging technologies such as UV LEDs, non-line-of-sight communications and other telecommunication applications.

UV_6
International collaboration

The Centre is part of the Joint Research Centre for Wide Bandgap Semiconductor Technologies – a collaboration between the University of Sheffield and Nanjing University in China. It brings together Chinese and UK expertise in designing novel semiconductor materials and device technologies. Central to this research is the design of different crystal orientations for LEDs producing sunlight-quality bulbs that are ‘farmed’ as much as manufactured.

“One of the targets for the joint research is to achieve a novel and ultra-high efficiency white solid-state lighting, which will replace the conventional lighting sources. It will massively save energy, electricity consumption, and help lead to a very clean, sustainable and energy-consumption-efficient world in the next 10 – 50 years. It is definitely unique work in terms of our approach and ideas.” Professor Tao Wang, Director of the Centre for GaN Materials and Devices

More about the Centre

With world-class facilities for the advanced research of III-nitrides – from epitaxy to extensive material characterisation and device testing – and a large, dedicated team of research staff, PhD students and technical staff the Centre is one of the largest GaN research groups in the UK. Other exciting areas of research include on-chip integration of electronics and photonics and developing III-nitride micro-LEDs for next-generation displays.

The Centre for GaN Materials and Devices can offer the full project life cycle for industry collaboration – from future trends analysis, design, advanced epitaxy growth, device fabrication and devices characterisation to testing. The Centre is also part of the 7-year EPSRC Future Compound Semiconductor (CS) Manufacturing Hub, and the recently funded EPSRC Centre for Doctoral Training in Compound Semiconductor Manufacturing.

Find out more about The Centre for GaN Materials and Devices at http://gancentre.group.shef.ac.uk and follow us @GaNCentre.

Research into III-Nitride semiconductors help tackle global climate change challenges