Field electron emission theory beyond Fowler-Nordheim for nano-scale emitters

The standard Fowler-Nordheim theory has been widely used and achieved great success in description of field emission (FE) experiments for over 70 years. In this paper, we present the field emission models for carbon nanotubes, wide-band-gap nanowires, and metallic nanosheets, emphasizing the deviations against the Fowler-Nordheim theory and some aspects that have not been incorporated in the standard Fowler-Nordheim theory.