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Optically Absorbing Thermally Insulating Structures for Amorphous Chalcogenide Memories

IP.com Disclosure Number: IPCOM000079862D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

von Gutfeld, RJ: AUTHOR [+2]

Abstract

The use of amorphous to crystalline transformation as a method of storing information in a specially prepared structure which is optimized to give maximum energy absorption with controlled transformation may be obtained, by preparing both an insulating optically absorbing layer, as well as the active memory material, in a single evaporation process.

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Optically Absorbing Thermally Insulating Structures for Amorphous Chalcogenide Memories

The use of amorphous to crystalline transformation as a method of storing information in a specially prepared structure which is optimized to give maximum energy absorption with controlled transformation may be obtained, by preparing both an insulating optically absorbing layer, as well as the active memory material, in a single evaporation process.

Calculations of thermal profiles demonstrate that the temperature rise of a thin film subject to laser pulse heating can be substantially increased, if the temperature gradient at the memory film-substrate interface can be reduced. Generally, the memory films of interest are such that at least in one of the two states of the material, all the incident light is not absorbed by the memory film. In the above-proposed structure, this light will be absorbed by an underlay which is highly absorbing. In addition, this underlay will be highly thermally insulating, consisting basically of a material similar to the active memory itself.

Fabrication is accomplished by first evaporating a thin layer (of the order of 2,000 angstroms or more) of GeTe onto a MYLAR* or glass substrate. This is followed by a second evaporation of Ge-Te-As or some other additional element, to cross-link with the Ge-Te to form the memory material. The properties of the Ge-Te film are: (1) amorphous with a very low-thermal conductivity, comparable to MYLAR, (2) highly...