SE323144

1,156,903. Electroluminescence. SIEMENS A.G. 10 Jan., 1967 [14 Jan., 1966 (2)], No. 1311/67. Heading C4S. [Also in Division H1] An electroluminescent diode comprises a body of a III-V compound in which the radiation reproduced at a PN junction passes through an N-type zone the doping level of which is selected so that the absorption coefficient of the material is reduced to a minimum for the luminescence maximum of the radiation. As the concentration of donors in the N-type zone increases the band gap of the material increases resulting in a decrease in the absorption of radiation of a given wavelength. At the same time, however, the absorption due to free charge carriers increases so that the material exhibits a minimum total absorption for a given wavelength at a particular value of donor concentration. The band gap of the material of the N-type zone preferably exceeds that of the P-type zone by the luminescence half width. The band gap of the material of the P-type zone may be decreased by counter doping, for example by alloying a pellet containing Sn as well as Zn to an N-type GaAs wafer to form the junction. The composition of the P-type region may differ from that of the N-type region, for example if the N-type region is of GaAs the P-type region may be of (Ga 1 - r In r ) (As 1-s Sb s ) where r # 0, s # 0 and r + s > 0. As shown, Fig. 2, a P- type zone 2 is produced by epitaxial deposition on the plane face of a hemispherical N-type body 1 through which the radiation is emitted. The P-type zone may also be produced by alloying, Fig. 3 (not shown), or by diffusion.