The observation of crystalline materials in the scanning electron microscope (SEM)

Abstract

Contrast effects from electron channelling in crystalline solids can be observed in the scanning electron microscope by the correct choice of operating conditions. The crystallographic symmetry and orientation of specimen areas as small as 1 pm in diameter can be determined, and detailed quantitative information obtained about the density, nature and position of defects contained within the crystal structure. The backscattered, absorbed current and transmitted electron signals may all be used. With anticipated improvements in instrumentation the technique will be capable of providing all the information currently supplied by the more complex procedures of transmission electron microscopy. I N T R O D U C T I O NThe usefulness of an electron microscope for studies in the field of materials science is greatly enhanced if the instrument can provide information about the crystallography of the specimen under observation. In the conventional transmission electron microscope (CTEM) such information can be obtained from the diffraction and Kikuchi patterns which are generated as the electrons pass through the thin specimen. These patterns make it possible to determine the orientation, symmetry, lattice spacing etc. of small selected areas of the specimen, and micrographs can be recorded in specific diffracting conditions to image defects and other crystallographic features and enable these features to be identified.When solid specimens are examined in the scanning electron microscope (SEM), no directly analogous process is available. Crystallographic information can be obtained by the Kossel technique (Yakowitz, 1973) in which the fluorescent X-rays generated by the beam are diffracted by the crystal structure as they leave the specimen and form a series of conic sections on a suitably placed film. The patterns produced can be analysed to give accurate orientation and lattice spacing information. However, the technique is only applicable to a limited range of materials, and the patterns cannot be directly viewed or combined with topographic information. Alternatively, the spatial distribution of the backscattered electrons can be recorded on a film or viewing screen (Venables &

SIMS Studies of Semi‐Insulating InP Amorphized by Mg and Si

“…Although ~ome recrystallization has apparently occurred at 750~ the patterns are of very poor quality when compared to those from u n i mplanted material. These results seem to be inconsistent with other published results (6, 7), which indicate that major reordering of amorphous I n P occurs in the range from 450 ~ to 500~ It has been reported that, in addition to the degree of crystallinity, factors such as lattice strain of a few percent can result in loss of resolution or contrast in electron channelling patterns (9). For the Mg implants discussed here, lattice strain may be significant and could therefore be responsible for the discrepancy between our results and those of others regarding the recrystallization temperature for amorphous InP.…”

Image contrast enhancement of Ni/YSZ anode during the slice‐and‐view process in FIB‐SEM

“…It is supposed that too many SE2s are collected by the In‐Lens SE detector. SE2s are generated by BSEs, which are quite sensitive to the grain orientations leading to the channelling contrast (Joy, ; Canovic et al ., ). In addition, the In‐Lens SE detector may also collects a small portion of low‐angle BSEs, which will directly contribute to the channelling contrast.…”

“…In addition, the In‐Lens SE detector may also collects a small portion of low‐angle BSEs, which will directly contribute to the channelling contrast. Because the slice‐and‐view process always creates clean surface for SEM, channelling contrast could be visible (Joy, ).…”

Applications of electron microscopy in materials science and technology (microscopy in the modern world)*

“…A major aspect of this study was to monitor the local texture and its changes, during this grain growth/migration process, using the diffraction signals available through the relatively new electron back scattering (EBS) diffraction technique now becoming incorporated into SEM (e.g. Joy, 1975;Randle er al., 1988). This technique, EBS (Fig.…”