Abstract :
Internal field-assisted Ag–O–Cs photocathode with sandwich-like structure was successfully fabricated by depositing a silver electrode on the surface of Ag–O–Cs composite thin films that were pre-grown onto a conductive glass substrate. Enhanced photoemission was observed from Ag–O–Cs composite thin films when an internal assistant electric field was applied to the photocathode through the designed sandwich-like structure. The total increase of photoelectronic quantum yield corresponding to the applied 30 V bias was about 15.7% while the photocathode was irradiated by the light with wavelength of 510 nm. Theoretical analysis indicates that such an enhanced photoemission can be attributed to the field-induced variations in the energy-band structure of Ag–O–Cs thin films, including both the decrease of interfacial barrier between the embedded Ag nanoparticles and the CsxO (2≤x<3) semiconductor matrix and the degradation of the vacuum level at the surface.
