Electric field distribution and current emission in a miniaturized geometrical diode

Abstract

We study the electric field distribution and current emission in a miniaturized geometrical diode. Using Schwarz-Christoffel transformation, we calculate exactly the electric field inside a finite vacuum cathode-anode (A-K) gap with a single trapezoid protrusion on one of the electrode surfaces. It is found that there is a strong field enhancement on both electrodes near the protrusion, when the ratio of the A-K gap distance to the protrusion height d=h < 2: The calculations are spot checked against COMSOL simulations. We calculate the effective field enhancement factor for the field emission current, by integrating the local Fowler-Nordheim current density along the electrode surfaces. We systematically examine the electric field enhancement and the current rectification of the miniaturized geometrical diode for various geometric dimensions and applied electric fields.Published by AIP Publishing. [http://dx.

Field emission from carbon nanotube fibers in varying anode-cathode gap with the consideration of contact resistance

“…As studied in Ref. 8, this is purely a geometrical effect. Electrostatic simulations using COMSOL 25 on the local vacuum electric field at the tip center of the emitter confirms this scaling, also shown in Fig.…”

“…More importantly, as will be discussed below, the effective electric field enhancement factor ( β eff in Eq. (1)) near the emission tip is largely increased as the gap distance D decreases, especially when the fiber tip-to-anode distance d is smaller than fiber height h, d ≤ h, as recently studied by Lin et al 8 It is clear that in general the turn on voltage also decreases as the gap distance D decreases, as shown in Fig. 1c, which is also due to the increased cathode electric field and the increased field enhancement factor for a smaller AK gap.…”

“…[6][7][8] Carbon materials, such carbon nanotube (CNT) fibers, [9][10][11][12][13][14][15] have demonstrated promising properties for their use as field emitters, due to their large aspect ratios, and high electrical and thermal conductivities.…”

“…[18][19][20] Recently, it is shown that field enhancement factor strongly depends on the finite anode-cathode gap distance when the emitter tip-to-anode distance is comparable to or smaller than the emitter height. 8 In this paper, we study the FE characteristics of a CNT fiber emitter in different anode-cathode (AK) gap distances. We show that the field enhancement factor depends strongly on the finite AK gap distance, due to the combination of geometrical effects and possible change in fiber morphology.…”

The impact of cathode surface roughness and multiple breakdown events on microscale gas breakdown at atmospheric pressure

“…These phenomena also have significant implications in vacuum electronics, where ongoing research in electron sources 13,14 has focused on assessing groups of nanoemitters 15,16 and intentionally modifying device designs to better control field enhancement. 17 Thus, characterizing gas breakdown and electron emission for microscale and smaller devices is important across application and pressure, motivating studies on the responsible physical phenomena. Gas breakdown is typically driven by Townsend avalanche and predicted by Paschen's law (PL); 18 however, reducing gap sizes to microscale causes field emission to drive breakdown.…”