GB1195547A - Improvements in or relating to Luminescent Diodes - Google Patents

Abstract

1,195,547. Electroluminescence. SIEMENS A.G. 8 Nov., 1967 [9 Nov., 1966], No. 50686/67. Heading C4S. [Also in Division H1] A luminescent diode comprises a carrier crystal body, e.g. an A<SP>m</SP>B<SP>V</SP> material preferably of n-type GaAs, with a first part 4 of the surface of one zone 1 shaped to form a concave reflector, and with a metal layer 6 of good reflectivity, heat-conductivity and electrical conductivity, the remaining surface part 5 forming the radiation exit surface and provided with a reflection reducing coating. Layer 6 may be of Ag, Cu, Al or an alloy. Surface 4 may be part of a paraboloid (Figs. 1, 2 and 3, not shown); an ellipsoid optionally with P-N junction 3 in the vicinity of focal point F, Fig. 5 (and Fig. 4, not shown); or a sphere with the P-N junction between the sphere centre and the reflector surface (Figs. 6 and 7, not shown). Exit surface 5 may be plane or curved to at least partially focus the radiation, e.g. in Fig. 5 the spherical exit surface is confocal to focal point F 2 and in Fig. 3 the convex exit surface radius of curvature is less than the distance from focal point F to the exit surface. In Fig. 6 (not shown), zone 2 of the P-N diode is at the centre of the flat exit surface. Axial drilling along the axis A from either direction may be effected by electron, ion or laser beams, or gas or liquid jets while zone 2 may be produced by alloying, diffusion, or focused ion beam bombardment. Surface 4 may be polished before layer 6 is provided. The diode electrodes are contacted via terminal E 1 to coating 6 and terminal E 2 to zone 2 by a wire alloyed or in pressure contact with zone 2.