GHz bandwidth GaAs light-emitting diodes

Double-heterostructure GaAs/GaAlAs light-emitting diodes (LEDs) have been fabricated with the emitter regions beryllium doped to ${\text{2×10}}^{19}$ and ${\text{7×10}}^{19} {\mathrm{cm}}^{\mathrm{-3}}.$ The ${\text{7×10}}^{19} {\mathrm{cm}}^{\mathrm{-3}}$ doped emitters have an internal quantum efficiency of 10% and an optical modulation bandwidth of 1.7 GHz. The steady-state optical output power versus the input current shows an external efficiency of 2.5 μW/mA. The ${\text{2×10}}^{19} {\mathrm{cm}}^{\mathrm{-3}}$ emitters have internal quantum efficiencies as high as 80%, but a reduced cutoff frequency. The external quantum efficiency reaches 10 μW/mA. These high-speed LEDs are produced by reducing the radiative lifetime to 100–250 ps without significantly degrading internal quantum efficiency. The current results on heavily beryllium-doped LEDs exhibit, to the best of our knowledge, the highest external efficiencies to date for such high doping and efficiencies close to that observed for lower-doped LEDs.