Ultrafast photocathodes based on n-doped graphene emitters on compound semiconductor photoswitches

A photocathode based on n-doped graphene emitters in series to a GaAs photoswitch was fabricated and used for pulsed field electron emission. The n-doped graphene array emits at low turn-on fields (<; 3 V/μm). A fast photomodulation of the emission current with high on/off ratio ~200 was achieved with a semi-insulating (s.i.) GaAs photoswitch in a diode configuration. Different laser sources were used for these investigations.