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Use of Amorphous Films as Ternary Storage Devices

IP.com Disclosure Number: IPCOM000080198D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Matick, RE: AUTHOR [+3]

Abstract

It is known that chalcogenide films may be made to exhibit amorphous and crystalline states by application of heat. By use of a discrete time-intensity laser beam, the film may be partially crystallized and thus employed to exhibit three different states usable in both binary and ternary logic.

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Use of Amorphous Films as Ternary Storage Devices

It is known that chalcogenide films may be made to exhibit amorphous and crystalline states by application of heat. By use of a discrete time-intensity laser beam, the film may be partially crystallized and thus employed to exhibit three different states usable in both binary and ternary logic.

With respect to an chalcogenide film which is in its amorphous state, it is possible to choose a time-intensity profile of an illuminating laser beam in such a manner as to stop crystallization partway through the film, or let it proceed all the way.

When viewed in transmission from above, the opaqueness of a partway crystallized spot and a fully crystallized spot is similar, if the film thickness is chosen so as to allow the thickness of the fully crystallized spot to be great enough so that alpha(Cr)d(Cr) is larger than 2; where alpha(Cr) is the absorption constant of the crystallized layer and d(Cr) is the depth of the layer. When viewed in reflection from below, the fully crystallized spot is visible while the partially crystallized spot is not.

This effect may be realized by utilizing a 1400 A film and reducing the intensity required to obtain full crystallization by about 25 to about 45%. In principle, any amorphous film which is stable at room temperature should be usable. The inverse effect, partial amorphization of a crystalline film can be observed only in materials which are quenchable into the amorphous state.

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