Investigation of phosphorus-doped nanocrystalline diamond films for photocathode application

This work is devoted to an experimental study of electron photoemission from phosphorus-doped nanocrystalline diamond (NCD) films under the effect of laser radiation with a wavelength of 266 nm and a pulse duration of 15 ns. Homogeneous NCD films with a thickness of 50–1200 nm were grown on conductive silicon substrates using the CVD method. The phosphorus content in the films was changed by varying the phosphine content in the hydrogen–methane gas mixture and the substrate temperature. A relation has been established between the growth conditions, the thickness of NCD films, and the measured quantum efficiency of diamond photocathodes. It was shown that 50 nm thick heavily doped NCD films with H-terminated surface demonstrated the maximum quantum efficiency of 3⋅10−5.