Screening effects on field emission from arrays of (5,5) carbon nanotubes: Quantum mechanical simulations

Abstract

The simulation of field electron emission from arrays of micrometer-long open-ended ͑5,5͒ carbon nanotubes is performed in the framework of quantum theory of many electrons. It is found that the applied external field is strongly screened when the spacing distance is shorter than the length of the carbon nanotubes. The optimal spacing distance is two to three times of the nanotube length, slightly depending on the applied external fields. The electric screening can be described by a factor that is an exponential function of the ratio of the spacing distance to the length of the carbon nanotubes. For a given length, the field enhancement factor decreases sharply as the screening factor is larger than 0.05. The simulation implies that the thickness of the array should be larger than a value, but it does not help the emission much by increasing the thickness a great deal.

Field emission from non-uniform carbon nanotube arrays

“…Figure 2 shows I PA and the overall current density, J PA , defined as the total current divided by the area of the array. The peak in J PA at s  ≅ 2  h indicates the ideal spacing for FE applications [13,14]. Note that J PA is relatively small for s  <  h , so we shall focus most of our analyses to the region where s  >  h .…”

Discrete space charge affected field emission: Flat and hemisphere emitters

“…As a consequence, compared to other electron sources, such as photoemission and thermal emission, field emitter sources are much more profoundly affected by space charge near a single emission site, [1][2][3] space charge in the anode-cathode (AK) gap due to many emitters, [4][5][6] and field reductions at the apex associated with other close proximity emission structures otherwise known as "shielding" or "screening." [7][8][9] The present analysis is the first part of a two part study undertaken to understand these interacting and degrading effects. The first and present study treats space charge and how it is affected by surface roughness or geometric features modeled as hemispheres.…”

Effect of ballast-resistor and field-screening on electron-emission from nanodiamond emitters fabricated on micropatterned silicon pillar arrays

“…22 Figure 8 shows the field emission behavior of each of the structures fabricated on n-type silicon. 22 Figure 8 shows the field emission behavior of each of the structures fabricated on n-type silicon.…”