GB967439A - Improvements in or relating to opto-electronic circuit elements - Google Patents

Abstract

An opto-electronic circuit element comprises an electroluminescent radiating member integrally combined with a photo-sensitive member and an optical and/or electrical coupling between the members, the photosensitive member consisting of an AIIIBV compound or a mixed crystal of two or more AIIIBV compounds, the AIIIBV compound being a semi-conductor compound of an element (AIII) of the third column of the Periodic Table with an element (BV) of the second sub-group of the fifth column of the Periodic Table. Examples are compounds of an element of the group B, Al, Ga, In with an element of the group N, P, As, Sb. The compound can be one having an energy gap between 1eV and 2.5eV such as InP, GaP, GaAs, AlSb, AlAs or mixed crystals of GaAs and GaP which can be regarded as a compound GaAs1-xPx, in which O<x<1. The electroluminescent member can also be of an AIIIBV compound or a mixed crystal of two or more AIIIBV compounds suitably activated such as AlAs, GaP, AlP, InP or mixed crystals of GaP and InP. GaN is also referred to as particularly suitable. The electroluminescent member can have an energy gap exceeding 1eV. Preferably the electroluminescent member is a PN recombination radiation source, for which the AIIIBV compounds are suitable owing to their ability of being doped with activators to P-type or N-type conductivity. In a specific example the electroluminescent member can be a GaP crystal in which a PN transition is provided by using an acceptor such as Zn and a donor such as S. Between contacts to the P-region and N-region a voltage is applied in the forward direction to form a PN recombination radiation source which is integrally combined with, for example, on a common carrier, a photo-conductive member of GaAs provided with two contacts. The GaAs can be activated by incorporating impurities. The members can be connected in series to form a radiation intensifier. If an optical feed-back coupling between the radiating member and the photo-conductive member is desired, for example toobta in a bistable element or an electric amplifier unit, a semi-conductor member can be used which consists partially of GaP and partially of GaAs, one part passing over into the other via a gradual mixed crystal formation between these compounds. The GaP part may be formed as a PN recombination radiation source and the GaAs part as a photo-conductive member. Alternatively the electroluminescent member may be of ZnS activated with 10-3 atoms per mol. of Cu and 0.9 x 10-3 of Al, and provided between an Al electrode and a tranaparent tin oxide electrode on a glass carrier in the form of a layer 50 microns thick. For use as a radiation intensifier without optical feed-back coupling, a photo-conductive member of GaAs is connected in series on the same carrier beside the electroluminescent layer. If optical coupling is desired the photo-conductive member can be located on the side of the glass carrier opposite to the electroluminescent layer. A plurality of radiation members and/or photo-sensitive members can be provided. The photo-sensitive member can be constructed as a rectifying junction photo-voltaic member. Specification 967,438 is referred to.