arXiv subjects

J. P. Hoogenboom

Publications and source records attributed to J. P. Hoogenboom.

3 recordsLinked to original sources

arXiv2026

Fabrication and validation of a MEMS Electron Monochromator

Electron monochromators are essential components for many applications in electron microscopy but are often large and complex to operate instruments. In prior work, we presented a concept for monochromation using the fringe fields around miniature electrostatic elements. This concept could be realized with a compact monochromator design that requires tuning of only 7 power supplies. In this manuscript, we present the fabrication using MEMS technology and experimental testing of such a miniaturized monochromator. The fabrication scheme involves Bosch deep reactive ion etching to shape lens and deflector electrodes and focused ion beam milling to create nanoscale apertures in a silicon nitride membrane. All elements are then coated, precisely aligned and, after stacking, wire bonded to connect to external power supplies. We use the assembled prototype to measure the electron-beam energy spread in a scanning electron microscope demonstrating the energy filtering capability of the device. These results highlight the possibilities for making miniaturized electron optics instruments using alignment and stacking of different MEMS fabricated elements, representing an important step towards the development of compact, lightweight, high performance electron-beam instrumentation.

physics.ins-det↗

arXiv2026

Design and electron optics performance of a MEMS electrostatic electron monochromator

Monochromators are routinely used in Transmission Electron Microscopy and Electron Energy Loss Spectroscopy, to improve both spatial and energy resolution. State-of-the-art monochromators, however, are complex instruments that typically require additional electron optical correctors, limiting their implementation to the high-end, most expensive microscopes. Miniaturized monochromation relying on purely electrostatic fringe fields has recently been proposed as a means to realize a simpler and thereby more cost-effective and easier to operate high-resolution monochromator. Here, we present a design for such a compact, fully electrostatic fringe-field based monochromator. Our design consists of a superposition of an Einzel lens with a series of electrostatic deflectors and is entirely based on dimensions that can be realized with MEMS fabrication technology. Thanks to mild mechanical and electrostatic potential tolerances, the MEMS-fabricated electrodes can be passively aligned and only need seven regular power supplies. We present an analysis of spectral broadening due to diffraction in our monochromator design as well as particle simulations including stochastic Coulomb interactions. This analysis shows that our design can achieve a resolution of 19 meV while maintaining 128 pA of beam current and thus potentially achieve energy filtering comparable to state-of-the-art monochromators. Our MEMS monochromator could therefore bring the application of energy filtering into the domain of SEM and specifically allow higher resolution imaging in chromatic-aberration dominated low-voltage SEM.

physics.ins-det↗

arXiv2025

Basic considerations in the design of an electrostatic electron monochromator

Monochromators are an essential component in electron microscopy and spectroscopy for enhancing the spatial and energy resolution. However, its adoption in scanning electron microscopes remains limited because of its high cost and operational complexity. Through a thin-deflector analysis of an electrostatic homogeneous-field deflector, the extreme sensitivity of current monochromators to power supply drift and mechanical imperfections is demonstrated. These stringent alignment requirements for achieving optimal energy resolution often necessitate the use of additional correcting elements, adding to both cost and complexity. We demonstrate that the fringe-field deflector is instead less sensitive to these issues. Hence, a cost effective and simple monochromator design approach based on pure fringe fields is proposed. This monochromator does not need extra correcting elements and its optimal energy resolution is achieved by including momentary deceleration lenses surrounding the main deflector. This fully electrostatic design could be realized using MEMS technology, offering a simpler and more accessible approach for filtering beam energies.

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