Near-field detection cathodoluminescence investigations

To make near-field detection cathodoluminescence investigations with a resolution in the nanometre regime feasible, a scanning near-field optical microscope (SNOM) has been implemented in the chamber of a scanning electron microscope. Two different modes of operation which can yield complementary information on the specimen can be carried out in our set-up. In the first mode, the SNOM probe position remains unchanged while the primary electron beam is scanned in raster fashion over the sample surface. In the second mode, the sample is homogeneously irradiated by the electron beam while being raster scanned underneath the SNOM probe. Whereas in the first mode specimen properties such as diffusion lengths are accessible, the achievable spatial resolution in the second mode depends only on the size of the aperture at the apex of the SNOM probe. A spatial resolution of well below 50 nm has been achieved on bulk YAG specimens in the second mode using commercially available probes.