Frequency response of GaAlAs light-emitting diodes

The frequency response of epitaxial GaAlAs single-heterojunction light-emitting diodes was investigated as a function of active-layer hole-concentration and diode area. The modulation bandwidth can be considerably increased by high doping, but an upper limit is imposed by the space-charge capacitance of the diode. Further improvement of the frequency characteristics can be realized by reduction of the diode area. The highest 3-dB modulation bandwidth achieved in this investigation was 100 MHz.