Ultraviolet light emitting diodes for solid state lightning

Research Project, 2012 – 2015

Solid state lighting has enormous energy savings potential with a large, associated reduction of greenhouse gas emissions. A requirement is the availability of sufficiently efficient white light LEDs, with sufficient light quality, at a sufficiently low cost. White light LEDs are constructed by coating a high brightness, short wavelength LED with a thin layer of phosphor for wavelength conversion. For both high conversion efficiency and a high color rendering index, the short wavelength LED should emit in the ultra-violet (UV). For high luminous efficacy of the white light LED, the UV-LED should have very high efficiency. While most AlGaN-based UV-LEDs today are produced by metal-organic vapor phase epitaxy (MOVPE), recent research has shown that efficient UV-LEDs can be produced by the more environmentally friendly molecular beam epitaxy (MBE) technique when growth proceeds under metal-rich conditions. It is the purpose of the project to explore the unique possibilities offered by metal-rich MBE for the growth of high quality Al-rich AlGaN layers and LED structures. The growth kinetics of MBE will also be explored for the growth of advanced AlGaN nanostructures for improved injection and radiative recombination efficiencies. Prototype LEDs will be fabricated and fully characterized.