High-efficiency 650 nm thin-film light-emitting diodes
 
High-efficiency 650 nm thin-film light-emitting diodes ■
 
Cathleen Rooman, Cathleen Rooman, Cathleen Rooman, Reiner Windisch, Reiner Windisch, Reiner Windisch, M. Dhondt, M. Dhondt, M. Dhondt, I. Moerman, I. Moerman, I. Moerman, P. Mijlemans, P. Mijlemans, P. Mijlemans, Barun Dutta, Barun Dutta, Barun Dutta, Gustaaf Borghs, Gustaaf Borghs, Gustaaf Borghs, Roger Vounckx, Roger Vounckx, Roger Vounckx, Maarten Kuijk, Maarten Kuijk, Maarten Kuijk, P. Heremans, P. Heremans, P. Heremans
 
Abstract ■

The external quantum efficiency of planar light-emitting diodes (LED's) can be increased significantly by the approach of a non-resonant cavity (NRC) LED, which consists of texturing the top surface and applying a rear reflector. We demonstrate this approach for the first time on 650-nm InGaP/AlInGaP LED's. The LED's are fabricated using the processing techniques developed previously for 860-nm GaAs/AlGaAs NRC-LED's, which include wet thermal oxidation for the formation of a current aperture. With un-encapsulated NRC-LED's, we report an external quantum efficiency of 24\% for an emission wavelength of 655 nm. This is an 11-fold increase of the external quantum efficiency, as compared to conventional devices. Furthermore,, the efficiency is demonstrated to increase to 31\% by on-wafer encapsulation of the LED's. This results in an optical output power of 4 mW for a drive current of 7 mA