Title :
40% efficient thin-film surface-textured light-emitting diodes by optimization of natural lithography
Author :
Windisch, Reiner ; Dutta, Barun ; Kuijk, Maarten ; Knobloch, Alexander ; Meinlschmidt, Stefan ; Schoberth, Stefan ; Kiesel, Peter ; Borghs, Gustaaf ; Döhler, Gottfried H. ; Heremans, Paul
Author_Institution :
IMEC, Leuven, Belgium
fDate :
7/1/2000 12:00:00 AM
Abstract :
In conventional light-emitting diodes (LEDs), the external efficiency is limited by total internal reflection at the semiconductor-air interface. The problem can be overcome by the concept of the nonresonant cavity LED, which is an LED with a textured top surface and a rear reflector. The surface is textured using natural lithography. A monolayer of randomly positioned polystyrene spheres acts as a mask for dry etching. We present details about the optimization of the parameters of the texturing process for GaAs/AlGaAs LEDs. The studied parameters are the size of the spheres, the distribution of the spheres on the surface and the etching depth. Using optimized texturing conditions, we have realized un-encapsulated top-emitting oxide-confined GaAs/AlGaAs nonresonant cavity LEDs with an external quantum efficiency of 40%
Keywords :
III-V semiconductors; aluminium compounds; gallium arsenide; light emitting diodes; lithography; masks; sputter etching; surface texture; 40 percent; GaAs-AlGaAs; III-V semiconductors; dry etching; etching depth; external quantum efficiency; mask; natural lithography; nonresonant cavity; randomly positioned polystyrene spheres; rear reflector; textured top surface; thin-film surface-textured light-emitting diodes; un-encapsulated top-emitting oxide-confined devices; Gallium arsenide; Light emitting diodes; Lithography; Optical reflection; Optical surface waves; Rough surfaces; Substrates; Surface roughness; Surface texture; Transistors;
Journal_Title :
Electron Devices, IEEE Transactions on
