Optimized GaAs/AlGaAs light-emitting diodes and high efficiency wafer-fused optical up-conversion devices

Achieving a high internal quantum efficiency in GaAs/AlGaAs based light-emitting diodes (LEDs) for room-temperature operation at low current-density injection is crucial for applications such as optical up-converters based on the integration of LEDs and photodetectros. We report the experimental results as well as the theoretical analyses of the internal quantum efficiency of GaAs/AlGaAs LEDs as a function of the p-doping concentration of the active region for low current injection operation. By optimizing the doping concentration, we have achieved a close to 100% internal quantum efficiency for room-temperature operation of LEDs in the low injection current-density range, i.e., around 0.1 A/cm(2). An optical up-converter was fabricated using wafer-fusion technology by integrating the optimized GaAs/AlGaAs LED with an InGaAs/InP photodetector. The internal up-conversion quantum efficiency was measured to be 76%. (C) 2004 American Institute of Physics.