LIGHT-EMITTING SEMICONDUCTOR DIODES

摘要

1432215 Electroluminescence SIEMENS AG 19 Dec 1973 [28 Dec 1972] 49001/73 Heading C4S [Also in Division H1] A light emitting semiconductor diode has a P-I-N junction at which free carriers recombine to produce radiation, the diode consisting of one or more s./c. compounds and having a N-type zone and P-type zone separated by an intrinsic weakly conductive intermediate zone containing few charge carriers, doped with a substance producing isoelectronic centres and of thickness < the diffusion length of the free charge carriers in this zone. The three layers need not be of the same s./c. conductor and preferably differ little in their lattice constants. Operation may be in the forward or blocking direction, holes and electrons being injected into layer 2 and recombining at the isoelectronic centres. As a laser, layers 1 and 3 preferably possess a greater band gap energy than layer 2. Layers 1, 2 and 3 may be (Ga 1-x Al x )P with Zn dopant, pure GaP with N and/or Bi and (Ga 1-x Al x )P with Te dopants. Dopant concentrations are given. Displacement towards red emission is obtained with layers 1 and 3 of (GaAl)As 1-x P x and layer 2 of GaAs 1-x P x . The structured device may be obtained by differing proportions of a basic mixed crystal, e.g. or InGa x P 1-x or Ga x Al 1-x P. Emissions towards blue and red respectively may be obtained by Ga 1-y Al y P for layers 1 and 3 and Ga 1-z Al z P for layer 2 with 0 # z < y # 1 and similarly for In x Ga 1-x P. The Fabry Perot resonator of the layer of Fig. 2 (not shown) includes reflective surfaces (6), (7), and changes in refractive index produce an optical waveguide between layers 1 and 3. Additional N or Bi doping of layers 1 and 3 would not disturb production of the layer structure and formation of the isoelectronic centres, e.g. using gaseous ammonia, can be effected during the entire growth period. The thicknesses of layers 1 and 3 preferably do not exceed 10 Á for heat conductivity purposes, and layer 2 may be 0À1 to 3 Á, e.g. 0À5 Á thick. Three structures of GaAlAsP; InGaAlP and GaAlP for each set of three layers are specified.