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

Achieving a high internal quantum efficiency in $\mathrm{GaAs}∕\mathrm{AlGaAs}$ 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 $\mathrm{GaAs}∕\mathrm{AlGaAs}$ 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 $0.1\mathrm{A}∕{\mathrm{cm}}^2$ . An optical up-converter was fabricated using wafer-fusion technology by integrating the optimized $\mathrm{GaAs}∕\mathrm{AlGaAs}$ LED with an $\mathrm{InGaAs}∕\mathrm{InP}$ photodetector. The internal up-conversion quantum efficiency was measured to be 76%.