orientation map Au film composing

DTU Nanolab brings innovation into scanning electron microscopy

onsdag 06 maj 20
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Researchers from DTU Nanolab have developed a detector prototype for scanning electron microscopes (SEMs) that broadens their capabilities for materials' analysis.
“I work on improving a technique called Transmission Kikuchi Diffraction (TKD). Recently, we have achieved a significant performance enhancement of a TKD detector”, says Alice Bastos da Silva Fanta, Senior Researcher at DTU Nanolab.

The prototype detector is developed at DTU Nanolab in close collaboration with Bruker Nano GmbH who is about to commercialize the detector. “Both benefit from this collaboration” Alice B. S. Fanta underlines. “It gives us the opportunity to bring ideas forward effectively by combining our know-hows and resources.”

Optimal signals

Due to the Dr. Fanta´s development, the imaging capability of an on-axis transmission Kikuchi detector has radically improved.

“We faced several challenges when working with nanoparticles, because the detector must be in one position to image the particles, and then moved elsewhere to measure their orientation. This displacement of ~20 millimeters complicates the investigation, as it is often difficult to find the target particle again. Furthermore, for dynamic experiments where some parameter (e.g. temperature) is varied continuously, only either one of the signals could be collected.”

In other words, the difference between the two positions made it impossible to acquire images and diffraction signals simultaneously, limiting the capacity of the technique. Something had to change. “We proposed the idea of placing the imaging diode at the center of the detector screen, so that both signal could be captured simultaneously,” says Alice B.S. Fanta.

“We discussed this idea with our collaboration partner and they said: Go ahead – we will help you to make a prototype. We then realized a simple test to proof the concept: we glued one image diode in the middle of the screen and taped the necessary wirings around it – and it worked!” 

optimus tkd detector head schematic

“We now have optimized our prototype and it is operational for any sample. It is still a prototype, but it is just plug and play. For performing dynamic experiments, however, we needed a more sophisticated design. MEMS-chips (Micro-electro-mechanical-systems) for performing dynamic experiments in the TEM (transmission electron microscope) are commercial available, and show reliable and accurate results. However, they do not fit in the SEM. To adapt the instrumentation we develop a SEM holder for these TEM chips and now we got the full package: a detector that allows combining image and orientation map in one single experiments and the possibility to observe the microstructure behavior during dynamic experiments in the SEM with high accuracy and stability. 

New perspectives

The development of the detector will bring new perspectives, Alice B.S. Fanta believes: "SEMs are widely available microscopes, therefore developing SEMs characterization techniques has the potential to reach more people, labs and research facilities worldwide."

The combined facilities offered by DTU Nanolab for both fabrication and characterization of nanomaterials has given Dr. Fanta a clear advantage: “It is essential that we can fabricate our samples in the clean room. In this way, we have full control and knowledge on the samples characteristics, so that we can better concentrate on improving the performance of TKD for the benefit of our users, collaborators and industrial partners.”

 

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