Electroluminescent GaAs diodes have been fabricated in heavily doped (n > 1018 cm−3) GaAs using ZnAs2 or a Zn–Ga solution as a diffusion source. Using the Zn–Ga source, efficiencies of 1.3–1.4% for planar uncoated devices and 3.2–3.5% with an Epoxy lens are reproducibly obtained, and uncoated devices with efficiencies as high as 1.7% have been observed. A variety of GaAs crystals were evaluated in order to determine the type most suitable for the fabrication of diffused electroluminescent diodes. The optimum material was found to be Si-doped GaAs with n in the range (2–3) × 1018 cm−3. Both Czochralski and boat-grown GaAs were investigated. The device efficiency has been found to depend strongly on the etch-pit density of the crystal, with maximum efficiencies obtained for boat-grown GaAs with Δ < 103 cm−2. A series of zero dislocation crystals grown using the Czochralski technique was investigated and found to yield lower efficiency devices than boat-grown GaAs with an etch-pit density between 102 and 103 cm−2.

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A liquid-phase-epitaxial (LPE) double-heterojunction (DH) laser structure with an ∼1-μm ’’active region’’ consisting of ≳20 In1−xGaxP1−zAsz and InP lattice-matched thin layers is described. The thin-layer dimensions are small enough (<500 Å) to make quantum size effects relevant.

Data (77°K) are presented showing a dynamic Burstein shift of the absorption edge during spontaneous and laser operation of GaAs:Ge platelets. This is indicated directly by an increase in the relative transmission of the pump power through the sample with increased pump excitation. By the use of pumps with photon energies (1.527 eV) closely matched to the GaAs absorption edge (1. 513 eV), changes in the relative transmission of from 4 to 30% have been achieved. The data presented also show a change in the rate of decrease of the absorption with the onset of stimulated emission by the platelet.

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