Impulse Excitation of GaP Electroluminescent Diodes

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Abstract
This paper introduces an impulse technique, utilizing either electrical or optical excitation, capable of giving new information concerning the properties of luminescent systems. An analysis is included for both types of excitation and experimental results utilizing electrical excitation are reported. In particular it is shown that minority carrier lifetime in the active electroluminescent region can be evaluated directly. The technique is applied to red emitting GaP (Zn–O) electroluminescent diodes excited with short, <2 nsec, current pulses. The resulting time‐dependent luminescent response is then interpreted using a phenomenological model previously evolved. This model assumes that bound exciton radiation dominates the luminescent process at room temperature, where the experiments were carried out. Utilization of this theory allows the extraction of several of the important parameters of the radiative and nonradiative recombination processes. Minority carrier lifetimes between 3 to 10 nsec have been deduced for particular diodes, in good agreement with values previously reported. In addition, the experimental results can be interpreted as placing an upper bound on the hole equilibration time which is sufficiently small that it permits a significant simplification of the recombination kinetics in GaP.