Figure 1: Simulation of ion sputtering of a biased probe.
From: Field-directed sputter sharpening for tailored probe materials and atomic-scale lithography
(a) Simulated electric field surrounding a two-dimensional probe apex. This model demonstrates the expected field variation with surface curvature and simulated ion flight paths for 1.8 keV singly ionized Ar ions and a probe bias of 800 V (Vr=0.444). Greyscale colouration represents electric field, and green paths represent individual ion paths. Scale bar, 20 nm. (b) Normalized ion current density averaged over a region within 10 nm of the apex centre is shown to exhibit a square root dependence on the ratio of tip voltage to ion accelerating voltage (Vr). An ion flux of 1.0 corresponds to the flux generated at the ion source.
