Cathodoluminescence mapping with an energy-dispersive x-ray detector: principle, simulation and application

The observation of cathodoluminescent (CL) emission in a scanning electron microscope (SEM) offers a wealth of information as it allows to study the luminescence of materials on a nanoscale. In combination with elemental analysis (e.g. EDX), even more information can be extracted. Here we report on the use of the silicon detector, normally used for the energy-dispersive analysis of the characteristic x-rays, for the detection of (CL) light. Based on the working principle of an EDX detector we explain why this detector is sensitive to visible radiation. The response of the detector to the intensity of the CL light is highly non-linear. By using a purposely written software program, the detector behaviour was correctly simulated. We show that the signal in the low energy part of the EDX spectrum can readily be used to obtain CL mappings along with simultaneously recorded elemental mappings. This is illustrated on both powders and thin films. The main advantage of this method is that no additional software or hardware is required to obtain the mappings. Results are compared with CL mappings obtained by measuring the light output with a CCD-based spectrometer