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Structures for Reversible SmS Optical Memories

IP.com Disclosure Number: IPCOM000079292D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

von Gutfeld, RJ: AUTHOR

Abstract

It is known that SmS can occur in two different solid phases, metallic and semiconducting, at room temperature. The SmS material can be converted from the semiconducting to the metallic state by polishing, due to a pressure effect that appears to stress the material beyond the elastic limit. The SmS material can be returned to the semiconducting state by a short heat (laser) pulse, which is believed to result in a purely thermal phase transformation.

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Structures for Reversible SmS Optical Memories

It is known that SmS can occur in two different solid phases, metallic and semiconducting, at room temperature. The SmS material can be converted from the semiconducting to the metallic state by polishing, due to a pressure effect that appears to stress the material beyond the elastic limit. The SmS material can be returned to the semiconducting state by a short heat (laser) pulse, which is believed to result in a purely thermal phase transformation.

A scheme is proposed whereby SmS can become useful as a reversible optical memory. In Figs. 1 and 2, the light for the metal-to-semiconductor transition is incident from the left and causes localized heating. The light for the semiconductor-to-metal transition enters from the right. The more complicated multilayered structure (Fig. 2) is mainly to enhance the laser produced semiconductor to metal transition. The laser beam entering from the right produces a pulse of pressure on the SmS, without changing the SmS temperature appreciably. This produces the transition from the metallic-to-semiconducting state.

The following are the The following are the components of Fig. 1: components of Fig. 2:
1. SiO(2) overcoat. 11. SiO(2) overcoat.
2. SmS memory material. 12. SmS memory material.
3. Insulating material 13. Metallic layer,

(approx = 1,000 angstroms) good thermal conductor.

such as MYLAR*.
4. High-thermal expansion, optically 14. High-thermal

absorbing layer (1,000 angstr...