| Abstrakt: |
Depolarization, also called shielding or screening, is a key phenomenon that can reveal the conditions under which a macroscopic emitted current density is optimized in large-area field emitters (LAFEs) or clusters thereof, which are useful for vacuum nanoelectronic technologies. This phenomenon deserves special attention, particularly for the prediction of how the characteristic field enhancement factor (FEF), which quantifies how a characteristic barrier field is magnified with respect to an applied macroscopic field, changes when the emitters are electrostatically interacting. One parameter of interest for studying depolarization is the fractional reduction in the apex FEF, − δ. Surprisingly, existing formulas for − δ do not predict how the aspect ratio (ν ≡ the ratio of the longitudinal to the lateral dimensions) influences the depolarization in field emitters and, in turn, the related characteristic FEF. Here, we show by first-principles arguments that ν clearly influences depolarization and, as a by-product, propose an analytical formula for depolarization that contains a prefactor that clearly depends on ν. In addition, for sufficiently large distances between emitters, we present a proof that for any axially symmetric pair of conducting emitters, − δ falls off as a power law of the distance between the emitters with an exponent of − 3 , in contrast to the exponential-like fitting formulas found in the literature. This finding reinforces the universality of this behavior, as recently claimed. [ABSTRACT FROM AUTHOR] |
