Contrast inversion in neutral-atom microscopy using atomic cluster beams

Abstract

This work explores the possibility of using atomic cluster beams as a probe for neutral-atom microscopy (NAM) measurements. Using a beam of Kr clusters with mean size $\ensuremath{\sim}{10}^{4}$ atoms/cluster we demonstrate that topographical contrast can be obtained, similar to that in the case of monoatomic beams. Further, using atomically thin films of ${\mathrm{MoS}}_{2}$ grown on ${\mathrm{SiO}}_{2}\text{/}\mathrm{Si}$ substrate we show that NAM imaging using Kr clusters is also possible in domains where topographical contrast is not expected. Surprisingly, these images show an inverted contrast pattern when compared to the case of monoatomic beams. We attempt to understand these observations on the basis of angular distributions resulting from cluster-surface scattering. Finally, we discuss the implications of these results toward achieving a high lateral resolution neutral-atom microscope using atomic cluster beams as probe, with an estimated ultimate achievable lateral resolution up to 20 nm.