Control of charging in low‐voltage SEM

Charging of the specimen under electron beam irradiation is a common problem in scanning electron microscopy (SEM). It results in unstable imaging conditions and a loss in resolution due to defocus of the beam. In addition, it can cause permanent changes in some specimens from translocation of mobile ions under the influence of the induced electrostatic field. To minimize charging and its associated problems, the incident beam energy must be carefully chosen to be the value E2 at which a dynamic charge balance is obtained. This article presents data on E2 values for a variety of materials and demonstrates how E2 is affected by the choice of angle of beam incidence.