Effects of resonant tunneling in field emission

Nanostructures or adsorbates (ions, or molecules etc.) on cathodes form nearby quantum well(s) and modify the surface potential, which has significant effects on field emission [1-3]. In this work, we develop an exact analytical quantum theory for field emission from surfaces with a nearby quantum well, by solving the one-dimensional (1D) time-independent Schrcdinger equation. The theory includes effects of the quantum well (simplified as a square potential well with width d, depth H, and distance to cathode surface L), cathode properties (work function W and Fermi energy E
F
) and dc field F. It is found that the quantum well can lead to resonant tunneling enhanced field emission up to > 10
⁵
times of that from bare surfaces. In the meantime, the electron emission energy spectrum is significantly narrowed. The bounds of strong enhancement region of field emission are identified. The theory provides insights for the design of highly efficient field emitters to produce high current and highly collimated electron beams.