▎ 摘　　要

The quasiballistic electron emission from a nanocrystalline porous silicon (nc-Si) diode is drastically enhanced by using a monolayer-graphene film as the surface electrode. Due to little scattering losses in monolayer-graphene, the electron emission efficiency at room temperature is increased up to 6.3% that is considerably higher than that in the case of conventional thin metal films. The peak energy of emitted electrons can be tuned by the applied voltage while keeping narrow energy dispersion. The energy distribution becomes more monochromatic at a low temperature of around 150K. Monolayer-graphene acts as a highly transparent nanogrid for quasiballistic hot electrons. Published by AIP Publishing.