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Media for Magneto-Optic Recording using Hydrogenated Amorphous Carbon

IP.com Disclosure Number: IPCOM000040909D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bell, AE: AUTHOR [+3]

Abstract

Plasma deposited hydrogenated amorphous carbon layers are used for enhancement of Kerr rotation and corrosion protection of magnetic layers in M-O recording media.

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This is the abbreviated version, containing approximately 81% of the total text.

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Media for Magneto-Optic Recording using Hydrogenated Amorphous Carbon

Plasma deposited hydrogenated amorphous carbon layers are used for enhancement of Kerr rotation and corrosion protection of magnetic layers in M-O recording media.

The a-c:H layers are produced by plasma decomposition of a hydrocarbon gas in an RF diode system. The a-c:H films are deposited on a cathode under conditions of positive ion bombardment with energies in the range 300-1000 eV.

The properties of the a-c:H films produced in this way which are desirable for M-O media are as follows:

(a)The films are optically transparent and have a high refractive index (n=2.1) in the wavelength range of interest to optical recording (i.e. diode laser, =750- 850 nm). The films therefore provide an effective antireflection coating (RN20%) when deposited at close to one-quarter wave thickness, and resulting in an enhancement of the Kerr rotation figure of merit.

(b)Corrosion resistance of these films is good, as demonstrated by the stability of Kerr rotation.

(c)The films are mechanically hard and chemically inert.

(d)The thermal diffusivity of these films is low, so that the impact of thermal losses from the M-O layer is minimized and recording sensitivity is good.

(e)The plasma deposition method offers high deposition rates (>0.2 nm/sec.) and thus high throughput for low cost manufacturing.

In summary, it has been shown that optical coatings can be made from hydrogenated amorphous carbon films by a high...