Nitrides for the 21st century
Lead Research Organisation:
University of Manchester
Department Name: Physics and Astronomy
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.
People |
ORCID iD |
| Philip Dawson (Principal Investigator) |
Publications
Davies M
(2016)
A comparison of the optical properties of InGaN/GaN multiple quantum well structures grown with and without Si-doped InGaN prelayers
in Journal of Applied Physics
Davies M
(2015)
A study of the inclusion of prelayers in InGaN/GaN single- and multiple-quantum-well structures Inclusion of prelayers in InGaN/GaN single and multiple QWs
in physica status solidi (b)
Kundys D
(2016)
A study of the optical and polarisation properties of InGaN/GaN multiple quantum wells grown on -plane and -plane GaN substrates.
in Science and technology of advanced materials
Badcock T
(2013)
Carrier Density Dependent Localization and Consequences for Efficiency Droop in InGaN/GaN Quantum Well Structures
in Japanese Journal of Applied Physics
Hammersley S
(2015)
Carrier distributions in InGaN/GaN light-emitting diodes Carrier distributions in InGaN/GaN LEDs
in physica status solidi (b)
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
(2010)
Characterising the degree of polarisation anisotropy in an a -plane GaN film
in physica status solidi (c)
Davies M
(2016)
Comparative studies of efficiency droop in polar and non-polar InGaN quantum wells
in Applied Physics Letters
Badcock T
(2014)
Dynamics of carrier redistribution processes in InGaN/GaN quantum well structures Dynamics of carrier redistribution processes in InGaN/GaN quantum well structures
in physica status solidi (c)
Hammersley S
(2016)
Effect of electron blocking layers on the conduction and valence band profiles of InGaN/GaN LEDs Effect of electron blocking layers on the conduction and valence band profiles of InGaN/GaN LEDs
in physica status solidi (c)
Davies M
(2014)
Effects of an InGaN prelayer on the properties of InGaN/GaN quantum well structures Effects of an InGaN prelayer on the properties of InGaN/GaN quantum well structures
in physica status solidi (c)
Hammersley S
(2015)
Effects of quantum well growth temperature on the recombination efficiency of InGaN/GaN multiple quantum wells that emit in the green and blue spectral regions
in Applied Physics Letters
Schulz S
(2010)
Electronic and optical properties of nonpolar a -plane GaN quantum wells
in Physical Review B
Badcock TJ
(2010)
Electronic structure of a-plane GaN/AlGaN quantum wells
in Physica Status Solidi
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
(2012)
Exciton confinement in narrow non-polar InGaN/GaN quantum wells grown on r-plane sapphire
in physica status solidi (b)
Davies M
(2013)
High excitation carrier density recombination dynamics of InGaN/GaN quantum well structures: Possible relevance to efficiency droop
in Applied Physics Letters
Zhu D
(2012)
High-efficiency InGaN/GaN quantum well structures on large area silicon substrates High-efficiency InGaN/GaN QW structures on large area Si substrates
in physica status solidi (a)
Dunn A
(2016)
Investigating efficiency droop in InGaN/GaN quantum well structures using ultrafast time-resolved terahertz and photoluminescence spectroscopy Investigating efficiency droop in InGaN/GaN quantum well structures using ultrafast time-resolved terahertz and photoluminescence spectroscopy
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
(2012)
Modification of carrier localization in basal-plane stacking faults: The effect of Si-doping in a -plane GaN Modification of carrier localization in basal-plane stacking faults
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)
Schulz S
(2015)
Structural, electronic, and optical properties of m -plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory
in Physical Review B
Hammersley S
(2011)
Study of efficiency droop and carrier localisation in an InGaN/GaN quantum well structure
in physica status solidi (c)
Humphreys CJ
(2017)
The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem.
in Ultramicroscopy
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
Davies M
(2014)
The effects of Si-doped prelayers on the optical properties of InGaN/GaN single quantum well structures
in Applied Physics Letters
Oliver R
(2013)
The impact of gross well width fluctuations on the efficiency of GaN-based light emitting diodes
in Applied Physics Letters
Massabuau F
(2014)
The impact of substrate miscut on the microstructure and photoluminescence efficiency of (0001) InGaN quantum wells grown by a two-temperature method
in Journal of Crystal Growth
Massabuau F
(2014)
The impact of trench defects in InGaN/GaN light emitting diodes and implications for the "green gap" problem
in Applied Physics Letters
Dawson P
(2016)
The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells
in Journal of Applied Physics
| Description | The continuity of funding has enabled us to make significant advances in the following areas: 1. Understanding of the reduction in efficiency of GaN based LEDs at high drive currents. 2. Obtaining a comprehensive understanding of the role of field controlling layers in InGaN LEDs. 3. We have undertaken a program of research on GaN based structures in which the electric field which limits the efficiency is reduced. 4. Obtained more detailed understanding of the light generation processes in polar and non polar InGaN quantum wells. |
| Exploitation Route | The results of our work are available to the UK manufacturers of LEDS enabling them to be more competitive in this demanding market. |
| Sectors | Digital/Communication/Information Technologies (including Software),Education,Electronics,Energy |
| Description | Beyond blue |
| Amount | £464,496 (GBP) |
| Funding ID | EP/M010627/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2015 |
| End | 12/2020 |
| Description | Lighting the Future |
| Amount | £6,330,270 (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 | Study of semi-polar and non-polar nitride based structures for opto-electronic device applications |
| Amount | £385,382 (GBP) |
| Funding ID | EP/J001627/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 09/2011 |
| End | 07/2014 |
| Description | Collaboration with Tyndall Insitute |
| Organisation | University College Cork |
| Department | Tyndall National Institute |
| Country | Ireland |
| Sector | Academic/University |
| PI Contribution | Input to theory work done at Tyndall Institute |
| Collaborator Contribution | Theoretical input to program |
| Impact | Significant number of papers |
| Start Year | 2009 |
| Description | Light for life |
| Form Of Engagement Activity | Participation in an open day or visit at my research institution |
| Part Of Official Scheme? | Yes |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | Active engagement in making the general public aware of the consequences of our research. We have been asked to give repeat performances, most notably at the event "jodrell Live", which attacts many thousands of visitors. |
| Year(s) Of Engagement Activity | 2011,2012,2013,2014 |
| Description | Sci Bar talk |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Talk to organisation which aims to inform public of latest scientific research |
| Year(s) Of Engagement Activity | 2015 |