Paradox of low field enhancement factor for field emission nanodiodes in relation to quantum screening effects
1 Department of Mechanical Engineering, National Kaohsiung University of Applied Science, 415 Chien Kung Road, Sanmin District, Kaohsiung, 80778, Taiwan
2 Department of Electrical and Computer Engineering, University of Texas at Austin, 2501 Speedway, Austin, TX, 78712, USA
Nanoscale Research Letters 2012, 7:125 doi:10.1186/1556-276X-7-125Published: 14 February 2012
We put forward the quantum screening effect in field emission [FE] nanodiodes, explaining relatively low field enhancement factors due to the increased potential barrier that impedes the electron Fowler-Nordheim tunneling, which is usually observed in nanoscale FE experiments. We illustratively show this effect from the energy band diagram and experimentally verify it by performing the nanomanipulation FE measurement for a single P-silicon nanotip emitter (Φ = 4.94eV), with a scanning tungsten-probe anode (work function, Φ = 4.5eV) that constitutes a 75-nm vacuum nanogap. A macroscopic FE measurement for the arrays of emitters with a 17-μm vacuum microgap was also performed for a fair comparison.