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Display Using Amorphous Semiconductors

IP.com Disclosure Number: IPCOM000078246D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Weiser, K: AUTHOR

Abstract

The display shown can be optically read and altered without the use of standby power. A current pulse through the semiconductor laser produces a phase change in the chalcogenide film (amorphous semiconductor). The film is chosen so as to absorb the light emitted by the semiconductor laser. The incidence of energy from the laser to the film causes information to be stored in this location of the film. This information bit can be read by visual inspection, or by scanning across the film with a light beam or an electron beam. Alternatively, the semiconductor lasers can be energized at a current level too low to produce changes in the written portions of the film, in order to enable reading of the pattern.

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Display Using Amorphous Semiconductors

The display shown can be optically read and altered without the use of standby power. A current pulse through the semiconductor laser produces a phase change in the chalcogenide film (amorphous semiconductor). The film is chosen so as to absorb the light emitted by the semiconductor laser. The incidence of energy from the laser to the film causes information to be stored in this location of the film. This information bit can be read by visual inspection, or by scanning across the film with a light beam or an electron beam. Alternatively, the semiconductor lasers can be energized at a current level too low to produce changes in the written portions of the film, in order to enable reading of the pattern.

Fig. 2 shows an array of structures such as is shown in Fig. 1.

Here the dots indicate the location of the bits. The lines indicate those bits in which a phase change has taken place. Viewing is in a direction perpendicular to the lasing of the semiconductor diodes. The written bits are distinguishable, because the reflectivity of the crystalline and the amorphous states of the chalcogenide film differ appreciably.

Erasing is achieved by pulsing the laser in a different way, as by using different power and/or pulse length. A new pattern can then be written in the manner described previously.

Semiconductor lasers have ample output power to produce the phase changes required in the configuration of Fig. 1, without requiring opti...