Further scanning electron microscope studies of GaP electroluminescent diodes

Abstract

In green- and yellow-emitting GaP light-emitting diodes (LEDs) both charge collection (CC), i.e. barrier electron voltaic effect current, and cathodoluminescence (CL) signals were recorded as linescan traces across the p-n junctions. A CL dip was observed in every case, corresponding to the CC peak. This effect could be quantitatively interpreted in terms of the competitive origin of the CC and CL signals. The absence of dips from the CL linescan traces of red LEDs can be explained in terms of the saturation of the CL in these diodes at the beam power levels used in the SEM.