Gated carbon nanotube-on-silicon-post field emitter cell. Upper: schematic drawing of cell; lower: scanning electron micrograph of cell with carbon nanotubes on a silicon post centered in a diameter chrome gate aperture.
Fabrication sequence of gated carbon nanotube-on-silicon-post field emitters. (a) Fabricate gated silicon post using documented method (see Ref. 21 and 22). (b) Deposit catalyst layer and dip in HF to remove catalyst from oxide surfaces and cell sidewalls. (c) Heat to form catalyst islands on silicon post and to diffuse catalyst into gate metal. (d) Grow carbon nanotubes by CVD from catalyst islands.
Schematic diagram of the hot-filament-assisted CVD reactor used for nanotube growth.
Fabrication sequence of gated nanotubes-in-open aperture field emitters. (a) Form aperture through gate metal and thermal silicon dioxide insulator on silicon substrate. (b) Deposit conformal silicon dioxide by CVD. (c) Directional reactive ion etch to remove CVD oxide from horizontal surfaces and etch into silicon at bottom of aperture, forming vertical oxide spacer layer on sidewall. (d) Deposit catalyst layer. (e) Glancing-angle sputtering removes catalyst from top of spacer layer and gate. (f) Grow nanotubes on the bottom and spacer sidewall of cell.
Schematic drawing and scanning electron microgaph of gated nanotubes-in-open aperture field emitter cell. The gate diameter and the oxide spacer thichness are 1.7 and , respectively. The SEM was taken at a 45° tilt.
Transmission electron microgaph of a diameter multiwalled carbon nanotube grown under similar conditions. (Courtesy of Dr. Kim Pierson, Univ. of Wisconsin, Eau Claire, WI).
Gated carbon nanotube on-short Si-post field emitter cell. Upper: schematic drawing of cell. Lower: scanning electron micrograph of cell with nanotubes on a short silicon post centered in a diameter platinum gate aperture.
Anode-current–gate voltage characteristics from a 33 000 cell array of nanotubes-on-silicon post emitters with a total array area of .
Anode current from array of cNT-on-Si post emitters shifted to lower voltages (left curve) after dosing with water vapor. Operating at high current in UHV desorbed water and the original (right) curve was recovered. The two curves were reproducible upon adsorption and desorption of water.
Anode current-time characteristics from an array of 3840 cNT-on-Si post emitters obtained at gate voltage under xenon.
Emission electron energy distributions from array of cNT-on-Si post emitters. Gate voltages are marked.
Anode current from array of cNT-on-Si post emitters at (left curve) and at room temperature (right curve).
Constant potential contours near the tip of a nanotube shaped tip (, ) where the charge near the apex has been reduced from electrons needed to fully screen the applied field ( between plates apart) to electrons.
Anode-current (open circles) and gate current (filled triangles) characteristics from a 40-cell array of gated cNT-in-open aperture emitters (cell shown in Fig. 5). Inset shows the Fowler–Nordheim plot of the anode current.
Anode-current–gate-voltage characteristics of array of cNT-on-short Si post emitters obtained under UHV conditions and under hydrogen. Inset shows Fowler–Nordheim plots.
Anode-current–gate-voltage characteristics of a 20-cell array of cNT-in-open aperture emitters obtained at -and hydrogen. The Fowler–Nordheim plots are shown in the inset.
Anode-current-time evolution showing regenerative effect of hydrogen on oxygen-degraded array of cNT-on-short Si post emitters.
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