The work function ϕ, the bandgap Eg, the threshold energy level Et, for the inelastic scattering of excited electrons and the threshold energy transfer Ed for the onset of structural ionisation damage are clearly of major significance in various actively developing forms of hot carrier imaging. Two exciting examples here are the ability to image small and dynamic local changes in work function by PEEM and as well as mapping the variations in electronic structure between p and n-type regions of a semiconductor by SE imaging in the SEM. More recently still there have been indications that the SE signal in the ESEM might be sensitive to local changes in bandgap and suggestions that it might be even possible to image spatial variations in pH. It is increasingly clear that if these attractive opportunities are to be efficiently explored and developed, systematic and preferably quantitative observations are needed. Such work requires specimens whose atomic and electronic structure is either fully known beforehand or can be deduced from other signals available in a situation where the physical processes in the microscope are well understood.
Secondary Electron Emission from Dielectric Materials of a Hall Thruster with Segmented Electrodes