Anode distance effect on field electron emission from carbon nanotubes: a molecular/quantum mechanical simulation

Area of Science:

• Materials Science
• Quantum Chemistry
• Nanotechnology

Background:

• Field electron emission is crucial for nanotechnology applications.
• Accurate simulation of electron emission from carbon nanotubes is essential.
• Classical methods may not fully capture quantum effects in nanostructures.

Purpose of the Study:

• To simulate field electron emission from single-walled (5,5) carbon nanotubes using quantum chemistry.
• To investigate the influence of anode-apex distance on emission properties.
• To compare quantum chemistry simulations with classical finite element calculations.

Main Methods:

• Quantum chemistry simulations were employed.
• Field electron emission from (5,5) carbon nanotubes was modeled.
• Anode-apex separation effects were analyzed.
• Simulations were compared against classical finite element calculations.

Main Results:

• Classical finite element calculations overestimated the field enhancement factor by approximately a factor of 2 for capped carbon nanotubes.
• Effective work function lowering, due to field penetration, significantly impacts emission probability.
• A unique decrease in effective work function with increasing anode-apex separation was observed for capped carbon nanotubes.

Conclusions:

• Quantum chemistry provides a more accurate description of field electron emission from carbon nanotubes compared to classical methods.
• Field penetration and its effect on work function are critical factors in understanding electron emission.
• The observed decrease in effective work function has a quantum mechanical origin and warrants further investigation.