Physics of GaN Quantum Well Structures

Lead Research Organisation: University of Manchester
Department Name: Physics and Astronomy


Over the last fifteen years Light Emitting Diodes (LEDs) have revolutionised lighting. This has been achieved because GaN quantum well structures emit blue light very efficiently, enabling the manufacture of LED lighting that will replace incandescent and compact fluorescent bulbs. This will have a significant impact on global energy use. For example the use of LED light bulbs could reduce the global amount of electricity used for lighting by 50%. In the US alone this would eliminate the need for 133 new power stations (1 GW each), corresponding to 255 million tons of CO2, and save $115 billion of electricity costs ("The Promise of Solid State Lighting for General Illumination", OIDA Report for the US Department of Energy, 2000). Yet GaN promises even more if the range of available wavelengths is broadened. In particular, greater energy savings can be achieved with bulbs that have separately controllable blue and green LEDs, to better match the solar spectrum. However, the maximum external quantum efficiency is 20 % for green LEDs compared to 70 % for blue LEDs. To overcome this problem requires detailed studies of the underlying physics of the light emission processes.

In this project the student will undertake laser spectroscopy of a range of epilayers and QW structures whose properties will be targeted at understanding the relation between recombination efficiency, crystal structure and carrier localisation to enable the production of high efficiency green LEDs. This work is part of a collaboration between the School of Physics and Astronomy in Manchester and the Materials Science Department at the University of Cambridge. The student will be based in the Photon Science Institute in Manchester and will collaborate with the group in Cambridge who grow the QW structures and undertake electron microscopy and x-ray.

The work in the project will contribute to the major themes of physical sciences, energy, and manufacturing the future, specifically addressing the area "Photonic Materials and Metamaterials".


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