Fig. 2: Field emission (FE) characteristics at nanoscale.
a The experimental field emission current-voltage Im-Vm curves (solid lines) of the tungsten nanotip with an apex radius of 4 nm across different nanogaps. The dotted lines represent the theoretical IMG-VMG-eff data based on the Murphy-Good (MG) FE equation (VMG-eff = VMG/CMG ≈ Vm, where CMG is correction factor). b The corresponding experimental Fowler-Nordheim (FN) plots (solid lines) and the corresponding FN plots (dotted lines) based on the MG FE equation (VMG-eff = VMG/CMG ≈ Vm) of the tungsten nanotip with an apex radius of 4 nm. c The applied voltages Vm at a field emission current (Im) of 2 nA as a function of the ratio of experimental apex radius to gap length (Rm/dm) in logarithmic coordinates (scatterplots), along with the corresponding negative exponent n1 (solid line). d The field enhancement factors γa obtained from simulation as a function of simulated apex radius to gap length (Rt/dt) in logarithmic coordinates (scatterplots), along with the corresponding negative exponent n2 (solid line). e The product γa·Vm of the field enhancement factors γa and the applied voltages Vm at Im = 2 nA as a function of R/d in logarithmic coordinates (scatterplots), along with the corresponding negative exponent n3 (solid line).
