High-throughput nanoparticle analysis in a FEG-SEM using an inexpensive multi-sample STEM-ADF system

Nanotechnology research requires the routine use of characterization methods with high spatial resolution. These experiments are rather costly, not only from the point of view of the expensive microscopes, but also considering the need of a rather specialized equipment operator. Here, we describe the construction of an inexpensive and simple device that allows the analysis of nanoparticle in a FEG-SEM; images can be generated at high magnifications (ex. x500.000) and with nanometric resolution. It is based on the acquisition of transmitted electrons annular dark field (TE-ADF) signal; the systems can carry up to 16 TEM samples and, it is compatible with SEM sample exchange air-lock. Performance test have shown the measured ADF signal showed the atomic number and thickness dependence for transition metal nanoparticle about 10 nm in diameter. Also, the signal quality is high enough that the determination of the histogram of size distribution can be performed using a conventional image processing software, for gold particles in the range of 2-10 nm in diameter. The developed ADF device allows a much faster and cheaper high spatial resolution imaging of nanoparticle samples for routine morphological characterization and, provides an invaluable high throughput tool for an efficient sample screening.