Double-heterostructure GaAs/GaAlAs light-emitting diodes ͑LEDs͒ have been fabricated with the emitter regions beryllium doped to 2ϫ10 19 and 7ϫ10 19 cm Ϫ3. The 7ϫ10 19 cm Ϫ3 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 W/mA. The 2ϫ10 19 cm Ϫ3 emitters have internal quantum efficiencies as high as 80%, but a reduced cutoff frequency. The external quantum efficiency reaches 10 W/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.
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