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Material contrast in scanning electron microscopy (SEM) is studied for several kinds of samples with an energy selective backscattered (EsB) electron detector using low voltage. The working conditions are optimized for every specimen and the contrast is quantified, in order to investigate the influence of the most important parameters on the performance: the primary beam voltage, the grid voltage of the EsB detector, and the working distance. Furthermore, strategies to avoid undesirable beam-induced sample damage like shrinkage in organosilicate glass (OSG) thin films or charging in polymer samples are discussed. in a OSG thin film on Si substrate after 3 min. scan with high magnification at Ep ¼ 20 kV. The EsB image (d) shows no shrinkage with Ep ¼ 1 kV.A. Garitagoitia Cid et al./Optimization of the SEM Working Conditions: EsB. Fig. 11. Blend of PS-PMMA with SiO 2 nanoparticles distributed on the surface. InLens images (a) and (c) shows charging and the polymers are not distinguishable. The corresponding EsB images (b) and (d) provide the material contrast between the PS (dark phase) and the matrix of PMMA. The SiO 2 nanoparticles can be clearly distinguished from the organic material.

Energy-filtered backscattered electron imaging in a scanning electron microscope is performed on a blend of zinc-phthalocyanine (ZnPc) and fullerene (C 60 ), whose morphology is characterized using a novel energy selective backscattered (EsB) electron detector in combination with low acceleration voltages for the primary electrons. Such blends are used as an active layer of organic solar cells in bulk heterojunction architectures. The key to optimizing the solar cell performance is understanding the morphology of the blend components. Comparing the results to TEM micrographs, the EsB detector allows for a simple and fast identification of the phases in the blend. The relevance of the findings for applying ZnPc-C 60 blends in solar cells is also discussed.