A new compact electron detector with REELS, EPES and elastic peak imaging capabilities for SEM

Abstract

A new energy analyser to be used as add-on in SEM with multiple operating modes is described. It uses a high energy resolution of the retarding field to combine high energy resolution with high sensitivity and small size in order to fit inside the microscope vacuum chamber. The electron optical transmission of retarding mesh is obtained from computer simulations of the electron trajectories and a general formula for calculating the energy resolution is deducted. The analyser can perform as secondary electron detector for scanning imaging with energy filtering capability. The elastic peak is fully energy resolved so that recoil energy losses of light elements are measured and mapped. REELS measurements are shown to illustrate the high dynamic range and sensitivity of the system. The analyser is also sensitive to photons when the analyser energy is set above the primary beam energy, thus repelling all electrons and the detector gain increases correspondingly. Cathodoluminescent sample areas are mapped and soft X-rays are detected increasing the detector sensitivity up to single photon detection.