Series in Microelectronics
edited by Wolfgang
Design of Nanorod-LEDs using
2013. 140 pages. € 64.00.
Gallium nitride based light emitting diodes (LEDs) have been established as powerful devices applicable for general lighting. The further development towards higher efficiencies is retarded by an efficiency droop at high injection currents. Furthermore the lack of highly efficient green emitters prohibits the fabrication of high-brightness white LEDs without lossy wavelength converters.
This dissertation deals with the design of a novel kind of LEDs, that is expected to overcome the aforementioned restrictions: the nanorod approach.
In the first part, the advantages of nanorod LEDs are outlined. Semiconductor physics with a focus on the anisotropic static and electronic properties of gallium nitride based LEDs are discussed extensively. A novel Auger model accounting for this anisotropy is introduced. Furthermore, a connection between Auger recombination and carrier leakage is proposed as a sophisticated explanation for efficiency droop.
The second part of the dissertation deals with physics-based simulations of two different nanorod designs: the core-shell approach, that is expected to find a remedy for efficiency droop, and monolithic white emitters as an alternative for wavelength-converted LEDs. The simulations employ an in-house developed transport simulator with the capability to include quantisation effects in quantum regions.
A final comparison of the analysed designs concludes the thesis.
Marcus Deppner was born in Halberstadt, Germany, in 1984. In 2009 he finished his studies in electrical engineering at the Otto von Guericke University Magdeburg, Germany, graduating as Dipl.-Ing. Subsequently he joined the Computational Electronics and Photonics Group at the University of Kassel. In 2013 he completed his doctorate on the computational modelling and physics-based simulation of III-nitride nanorod-LEDs.
Keywords: LED, Nanorod-LEDs
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