Low-voltage high-resolution SEM of biological samples
There are three reasons for the recent upsurge of interest in using the SEM at a beam voltage (Vo) around 1 kV (LVSEM). The most common one arises from applications in the semiconductor industry and emphasizes the reduction in charging artifacts and in subsurface beam damage obtainable at low VoThe second reason derives from the belief that, given instrumentation capable of producing a sufficiently small probe, the increased contrast in the topographic component of the secondary electron signal will permit an important improvement in real topographic spatial resolution.The third reason is that recent developments in instrumentation have shown that by coupling a cold field-emission source with a short focal length lens, it is indeed possible to obtain small probe diameters at low voltage. Although they are considerably larger than probes obtained at higher voltage, they are nonetheless smaller than the smallest topographical feature yet imaged in the secondary electron (SE) mode. (Fig 1)