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Opto-Electronic Amplifier and Logic Element

IP.com Disclosure Number: IPCOM000034950D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Van Zeghbroeck, BJ: AUTHOR

Abstract

Proposed is an opto-electronic device, which acts as the optical equivalent of the transistor and can be used as both an amplifier and a logic element. It consists of a photo-transistor, a laser diode and a blocking layer which prevents positive feedback and latching. The figure shows the vertical structure. The lower part of the device forms a hetero-junction bipolar transistor which acts as a photo transistor. High sensitivity of the photo transistor is obtained with a homo-junction at the base-collector interface and by using a thick and low doped collector layer. The top layers form a laser diode. In between both devices there is a blocking layer, which consists of a thick and heavily doped GaAs layer, sandwiched between two equally doped A1GaAs layers.

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Opto-Electronic Amplifier and Logic Element

Proposed is an opto-electronic device, which acts as the optical equivalent of the transistor and can be used as both an amplifier and a logic element. It consists of a photo-transistor, a laser diode and a blocking layer which prevents positive feedback and latching. The figure shows the vertical structure. The lower part of the device forms a hetero-junction bipolar transistor which acts as a photo transistor. High sensitivity of the photo transistor is obtained with a homo- junction at the base-collector interface and by using a thick and low doped collector layer. The top layers form a laser diode. In between both devices there is a blocking layer, which consists of a thick and heavily doped GaAs layer, sandwiched between two equally doped A1GaAs layers. The purpose of this layer is dual: first, it prevents any stray light from the laser to reach the light sensitive area of the photo transistor; and second, it prevents holes to flow from the laser diode into the transistor, since it confines the holes between the two barriers until they recombine. This blocking layer is crucial for proper operation of the device since it prevents positive feedback between the laser diode and the photo transistor, both optical and electrical.

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