Picosecond electron bunches from GaAs/GaAsP strained superlattice photocathode

• GaAs/GaAsP strained superlattices are excellent candidates for spin-polarized electron beam.
• Pulse spin-polarized electron beam is required for investigating the magnetic domain change.
• Picosecond electron bunches were achieved from GaAs/GaAsP superlattice photocathode.
• TEM observation revealed a small disorder of superlattice layers.
• Improvement of superlattice periodicity can achieve much faster electron bunches.

GaAs/GaAsP strained superlattices are excellent candidates for use as spin-polarized electron sources. In the present study, picosecond electron bunches were successfully generated from such a superlattice photocathode. However, electron transport in the superlattice was much slower than in bulk GaAs. Transmission electron microscopy observations revealed that a small amount of variations in the uniformity of the layers was present in the superlattice. These variations lead to fluctuations in the superlattice mini-band structure and can affect electron transport. Thus, it is expected that if the periodicity of the superlattice can be improved, much faster electron bunches can be produced.