Quantitative analysis to the electric field generated at a nano-tip and the effect of the tip base

Nanotips are the main components in most of the powerful nanotechnology tools like scanning tunneling microscope (STM) and scanning transmission electron microscope (TEM). Therefore the improvement of the performance of these microscopes relies on fabricating extremely sharp tips with well defined shapes. Tips with an apex radius of a few nanometers are often characterized in the field ion microscope (FIM) or the field emission microscope (FEM), to estimate their sizes. However, these methods are only sufficient for characterizing the very end of the tip. Here we present a quantitative model that links the electric field, which is adequate to generate either FIM or FEM images at certain applied voltages, to the radius of the nanotip and to the radius of the tip base as well. This model introduces a more accurate method to estimate the overall tip shape over a relatively long range.