| AVS 65th International Symposium & Exhibition | |
| Advanced Ion Microscopy Focus Topic | Thursday Sessions |
| Session HI-ThA |
| Session: | Emerging Ion Sources, Optics, and Applications |
| Presenter: | Susanne Schulze, University of Cambridge, UK |
| Authors: | S. Schulze, University of Cambridge, UK D.J. Ward, University of Cambridge, UK M. Bergin, University of Cambridge, UK S. Lambrick, University of Cambridge, UK W. Allison, University of Cambridge, UK J. Ellis, University of Cambridge, UK A. Jardine, University of Cambridge, UK |
| Correspondent: | Click to Email |
Some of the major insights in the development of modern materials have come from scanning probe, electron, and ion microscopy, with advances in resolution and sensitivity enabling new material science. While charged particle beam techniques are widely used they have the serious drawback of causing damage to sample surfaces, while scanning probe techniques are limited to relatively flat surfaces and suffer from limited scan speeds. Instead, we are pursuing a different approach, using neutral atom beams. Here we will report on recent advances and development of the scanning helium microscopy (SHeM) technique.
Since SHeM uses a neutral beam of helium atoms at very low energy (<100 meV), the technique is suitable for measuring a variety of samples including insulators, semiconductors, organic and biological species. It is particularly attractive as the approach does not require any complicated post processing techniques. We will report on recent studies on range of materials and potential new applications, including measurements performed in collaboration with colleagues at the University of Newcastle (Australia) [1,2]. A particular focus will be on describing the underlying mechanisms of contrast formation.
Many of the technological challenges associated with SHeM have now been addressed, including helium focusing, sample preparation and nanoscale manipulation, thus enabling preliminary instruments to be developed[1,2,3]. One of the remaining challenges is adequate detection of neutral atom beams, which is a particular problem due to helium’s high ionization energy[3]. Applications that require time-sensitive measurements require a small ionization volume; however, when very high temporal resolution is not required, as with SHeM, very large ionizers with high detection efficiencies can be used. We will also report a recently developed detector, based on the approach recently applied to surface spin-echo experiments [4,5,6], and having the highest yet reported sensitivity for helium atoms.
[1] Nucl. Instr. Meth. Phys. Res B 340 76-80, 2014.
[2] Nature Communications, 7, 10189, 2016.
[3] “Atom, molecule and cluster beams”; Springer: Berlin, (2000).
[4] Phys Rev Lett. 105, 136101, 2010.
[5] Phys. Rev. Lett. 117, 196001, 2016.
[6] Phys. Rev. Lett., 52 (19), pp. 5085‐5088, 2016.