Frequency response of spontaneous mode electroluminescent diode at low injection levels

The expression for the emitted photon flux of a non coherent electroluminescent diode of flat geometry is determined. Analysis covers both steady-state and transient response; the latter is related to the area and edge emission, respectively, and found to be limited by the diode impedance, by transit time effects in the p and n regions, and by radiation absorption losses. The possibility of an increase of both the external quantum efficiency and modulation cutoff frequency is discussed applying the derived results to the GaAs electroluminescent diode.