Nanocrystalline AlN:Si field emission arrays for vacuum electronics

Abstract

Nano‐crystalline AlN:Si cold cathodes were grown by molecular beam epitaxy on prefabricated silicon μ ‐tip field emission arrays (FEAs). The investigated FEAs showed an uniform tip distribution and reproducible emission properties. Current densities of up to 0.7 mA for a 4 × 106 tips array (1 tip/μm2) have been achieved at a relatively modest voltage of ∼ 60 V. The emitters revealed a good current stability with fluctuations of about 4% at constant voltage. The FEAs demonstrated a 40‐fold decrease in operating voltage for a given current following the “activation” of the surface by high field conditioning. The corresponding changes in slope of the Fowler–Nordheim plot and UV photoemission spectra confirm that the surface cleaning causes a reduction of the surface emission barrier at least by factor of 3. The observed large electron affinity of the as loaded surface is presumed to be caused by the adsorption of oxygen and carbon containing species. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fabrication and field emission property of a Si nanotip array

“…Using the pure Si work function of 4.7 eV, we can roughly estimate β to be as large as 1100 for our current nanotip array. Since β depends upon 1/r (r is the curvature radius of the tip end) [24], the large field enhancement factor is intimately connected with the unique structure of the Si nanotips. Although an exact size of the tip end cannot be reflected in our AFM observations, the Si tips located at the triple points can still be observed to be very sharp (figure 1(c)), which is responsible for the remarkable increase of β.…”

“…Although an exact size of the tip end cannot be reflected in our AFM observations, the Si tips located at the triple points can still be observed to be very sharp (figure 1(c)), which is responsible for the remarkable increase of β. Furthermore, it is known that the surface bonding structure of a nanotip has a large influence on the field emission property [22,24]. The present Si nanotips are fabricated by chemical etching in a dilute HF solution.…”

Self-organized nanostructures in silicon and glass for MEMS, MOEMS and BioMEMS

“…In addition to its light absorbing effect, 'Black Silicon' can also be utilized for micro-fabricated cold cathodes [5], an electron emitting structure.…”

Fused silica ‘glass grass’: fabrication and utilization

“…For comparison, nanostructured surfaces realized in form of the 'black silicon' are currently used as light absorbers, such as antireflective coatings and enhancement of solar cells [28], electron emitters [29], catalyst carrier [11] and mechanical applications such as direct bond interfaces [12 or 13].…”