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Carbon Whisker Formation

IP.com Disclosure Number: IPCOM000088730D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+2]

Abstract

It has been found that thin carbon whiskers can be formed during ion bombardment of a carbon electrode. The diameter of the whiskers is 125+/- 30 angstroms, and the length is 1 to 10 microns. This is an unusually high aspect ratio, and the thickness has been found to be uniform and reproducible.

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Carbon Whisker Formation

It has been found that thin carbon whiskers can be formed during ion bombardment of a carbon electrode. The diameter of the whiskers is 125+/- 30 angstroms, and the length is 1 to 10 microns. This is an unusually high aspect ratio, and the thickness has been found to be uniform and reproducible.

The figure shows a carbon ion source which includes cathodes 1 and 2 and an anode 3 arranged in a conventional Penning ion source configuration. The upper cathode 1 is generally cylindrically shaped, while the lower cathode 2 has a general disc shape with a central opening 4. The cathodes 1 and 2 and the anode 3 thereby form a chamber 5 into which argon is introduced from a source
6. The cathodes are energized with a 1000-eV source 7.

The carbon whiskers form on the cathode surfaces, indicated by numeral 8, which are bombarded with argon ions at 1000 eV from a DC glow discharge created in the chamber 5. The operating parameters are: Argon pressure 10 microns

Cathode voltage 1000 v

Cathode current 50 milliamperes

Magnetic field-approx. 200 gauss.

During operation, the surfaces of each cathode 1 and 2 are sputter-etched. After 10 minutes, each surface is covered with cones about 3 microns long, from which extend thin whiskers up to 10 microns long. It is believed that the whiskers are formed by the diffusion of carbon atoms along the cones to the tip, enhanced by the strong local electric field.

The uniformity of the diameter of these whiskers (125+...