A cathodoluminescence detection system for TEM/STEM

The ability to correlate near-atomic resolution TEM images of defects with their cathodoluminescence (CL) spectra holds promise as a powerful technique for the study of the electronic structure of defects in semiconductors. We have constructed a CL detection instrument fitted to a Philips 400T electron microscope, similar to that described by Roberts, as shown in Fig. 1. The instrument uses an ellipsoidal mirror for light collection allowing operation in the TEM, STEM and REM modes in a relatively clean vacuum, and is compatible with the ELS and EDS modes. The ellipsoidal mirror was designed to collect the maximum amount of emitted light within the limitations of the spacing between the specimen holder and the upper pole piece of the twin lens, as shown in Fig. 2 and 3. The length of the major axis is 61.2 mm and that of the minor axis is 12.1 mm.