| Description |
Nitride based ultra-violet (UV) light emitting diodes (LEDs) have attracted great interest due to their potential applications in the fields of water purification, phototherapy and solid state lighting. Although advances have been made in the epitaxy and fabrication technologies of these devices, low external quantum efficiency is observed for LEDs emitting in the UV-B and UV-C regions. Hence for the optimization of deep UV LEDs, extraction of light is an important issue. In this talk two methods to improve the light extraction will be presented. Firstly, the use of novel geometries, e.g. interdigitated finger contacts, to ensure uniform current injection, decreased series resistance, and improved heat extraction will be discussed. Secondly, a nanopixel contact LED design, consisting of an array of Pd ohmic contact pixels and an overlying Al reflector layer, for enhanced light extraction will be presented. Based on this design a two fold increase in the light output, compared to large area Pd contacts has been demonstrated.
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