30-kV spin-polarized transmission electron microscope with GaAs-GaAsP strained superlattice photocathode

摘要

A spin-polarized electron beam has been used as the probe beam in a transmission electron microscope by using a photocathode electron gun with a photocathode made of a GaAs-GaAsP strained superlattice semiconductor with a negative electron affinity (NEA) surface. This system had a spatial resolution of the order of 1 nm for at 30keV and it can generate an electron beam with an energy width of 0.24 eV without employing monochromators. This narrow width suggests that a NEA photocathode can realize a high energy resolution in electron energy-loss spectroscopy and a longitudinal coherence of 3 × 10~(-7) m.