Investigation of the influence of several diode parameters on the light-delay time in large-area SH-junction LED´s

The influence of several diode parameters on the light-delay time of large-area Si/Zn doped GaAs-GaAlAs SH-junction LED´s has been investigated experimentally. Beside the dominant influence of the depletion-layer capacitance, the extrapolated saturation current, the series resistance, and the non-linearity of the transfer function between diode current and light output have to be considered to explain the observed spread of delay times at low and medium pulse currents. An analytical expression for the delay time in terms of four or five diode parameters which are easily measurable at low frequencies is given. A satisfactory agreement between calculated and measured results for low and medium pulse currents is achieved only if the nonlinearity between light emission and current is included in the analysis. This effect has not been discussed in previous publications.