Analysis of the scanning electron microscope mirror image based on the dielectric surface microstructure

Abstract

This paper addresses hitherto unexplained phenomena associated with the electrostatic mirror technique, such as (i) the influence of the surface microstructural parameters of a polycrystalline dielectric (e.g., alumina) on mirror images, and (ii) the distortion of mirror images. The formation of a mirror image on an as-machined alumina surface was found to be nearly impossible, but on a polished specimen, possessing low surface damages, mirror images were easily formed. A smooth and low-damage surface seems to be a prerequisite for the formation of a mirror image. The size of mirror images, observed at different locations on a polished alumina surface, was found to vary significantly, indicating that an inhomogeneous surface charging occurs in polycrystalline dielectrics. It was shown that the variation in the grain and grain boundary volumes constituting the charged region is responsible for the variation in the size of the mirror image. The distortion of the mirror images was studied using single crystal quartz specimens. The asymmetry of the equipotential boundary—caused by (i) the tilt of the crystal axis (θ≠0°) with respect to the probing electron beam, or by (ii) the asymmetrical electron interaction volume, i.e., deviation from the standard pear shape—was demonstrated to be responsible for the distortion of the mirror images.

Electropolishing of surfaces: theory and applications

“…It produces the images by probing the specimen with a focused electron beam which scans across a rectangular area on top of the sample surface, and it has been vastly applied to characterising the nanometre surface morphology. [137][138][139][140] TEM has become a key tool to correlate the nature of the microstructure of metals and the alloys directly with their important physical and chemical properties. The metal specimen for TEM has to be delicately prepared in order to make it thin enough to let the electron transmit through.…”

“…It produces the images by probing the specimen with a focused electron beam which scans across a rectangular area on top of the sample surface, and it has been vastly applied to characterising the nanometre surface morphology. 137 138 139 –140…”

Surface conductivity of insulators: one-dimensional initial value problems and the inviscid Burgers equation

“…More recent techniques to measure charge dynamics in polymer materials have used a scanning electron microscope, which delivers a non-penetrating electron beam, and a time-resolved current measuring mechanism [9]. These techniques use methods such as pressure wave propagation [10][11][12], pulsed electro-acoustic methods [13][14][15] and mirror image methods [16][17][18][19][20]. The effects of charge accumulation are monitored via a measured current as the sample is irradiated (and so charged) until the accumulated charge reaches an asymptotic steady state.…”

“…The boundary condition for the transformed electric field at the free end of the sample must satisfy equation (4. 19), hence we have…”

Space-charge dynamics of polymethylmethacrylate under electron beam irradiation

“…In recent years, many experimental techniques have been proposed to measure space charge and its distribution in insulators [4]. The most popular and well developed methods include the pressure wave propagation (PWP) method [5][6][7], the pulsed electroacoustic (PEA) method [8][9][10] and the mirror image method (MIM) [11][12][13][14][15]. These methods have been successfully applied to the samples of polymethylmethacrylate (PMMA) [16], polyethylene (PE) [17], polyfluoroethylenepropylene (Teflon TM FEP) [18], polyimide (Kapton TM PI) [19] and polypropylene (PP) [20] etc.…”