A neutral helium atom microscope for high resolution microscopy of delicate surfaces

J. Ward, M. Bergin, A. P. Jardine, J. Ellis and W. Allison

Cavendish Laboratory, J.J. Thomson Ave, Cambridge, CB3 0HE

Helium atom beams have been exploited in surface science investigations because they can be formed into controllable beams, have immense surface sensitivity and a small enough wavelength for high resolution studies. In the current work I will cover the use of helium beams in the latest instrument in the helium scattering family: A helium atom microscope, that acquired first images recently [2].

Microscopy has been a major enabling technique for the development and understanding of materials from the bottom up. Some of the major insights in the development of modern materials have come from scanning probe, electron and ion microscopies, with advances in resolution and sensitivity enabling new material science. Unfortunately charged beam techniques tend to cause surface damage and scanning probe techniques are limited to relatively flat surfaces and suffer from limited scan speeds.

In 2013, in collaboration with colleagues at the University of Newcastle, NSW some of the first reflective mode images with a neutral helium beam [1,2] were acquired. In comparison with a charged beam microscope, the instrument delivers uniquely surface sensitive images with atomic resolution and critically produces no surface damage. Helium microscopy is suitable for measuring a variety of samples including insulator, semiconductor, explosive, biological and 3D self-assembled materials and being a real space technique does not involve complicated post processing techniques. Since generating the first images, in 2013 academic avenues have turned to investigation of potential contrast mechanisms that the technique affords, while also developing the instrument to increase sensitivity and resolution with the objective of commercially viable instrument in the near future.

[1] D. J. Ward et. al., Nature Communications, 7, 10189 (2016) doi:10.1038/ncomms10189

[2] D.J. Ward et al. Nucl. Instr. Meth. Phys. Res B 340 76-80, 2014.