Theoretical and experimental study of nanopore drilling by a focused electron beam intransmission electron microscopy

Abstract

Sub-10 nm nanopores drilled by a focused electron beam in a transmission electronmicroscope are widely used in solid-state nanopore devices for DNA translocation.However, there still remains much controversy surrounding the drilling mechanism. In orderto explain the drilling of nanopores by electrons, we undertook a theoretical considerationof the energy transfer from the fast electrons to the solid through such mechanisms aselastic and inelastic scattering. According to the calculations based on the scatteringcross-section, the direct atomic displacement cross-section induced by elasticscattering increases with increasing incident electron energy, while the ionizationcross-section and temperature increment decrease. We performed nanopore drilling in aSi3N4 membrane using two different electron energies, 200 and 300 kV, to identify the drillingmechanism. The dependence of the nanopore drilling on the incident electron energy waswell matched with the direct atomic displacement.