Alongside the well-established electron microscope, the more recently developed helium ion microscope (HIM) is gaining attention in the materials, life and biosciences due to its unique advantages that set it apart from the SEM. This presentation will serve as an introduction to the HIM including discussion of the ion-surface interactions that give rise to its strengths, and will present work being undertaken on the University of Melbourne's HIM in materials science, plasmonics, biomedical engineering and cell biology.
The probe size in the HIM is not significantly hindered by diffraction effects since the helium ion is much more massive than the electron, resulting in ultimate resolution on the order of 0.3-0.5 nm. The information depth from which ample secondary electrons are produced is also much closer to the surface than for SEM, resulting in images that show far more surface nanoscale topography. And images can be collected from insulating materials without the need for a conductive coating at the surface. Furthermore, while this is an ion beam, under high resolution imaging conditions minimal damage is typically observed from sputtering, but when used as a focused ion beam under milling conditions the HIM can generate nanostructures with greater fidelity than a standard gallium FIB.
These features of the HIM will be showcased with a number of pieces of work; high resolution imaging of soft biological structures, cell biology investigating red blood cells, pancreatic beta cells, and bacteria, biomedical devices, imaging nanostructured semiconductors, carbon nanomaterials, and nanofabrication with the dual He/Ne beam on gold.