Zn-doped InGaP/Te-doped ZnGaP on n-type GaAsP substrate homostructural light-emitting diodes has been reproducibly fabricated by liquid-phase epitaxy using a supercooling technique. The growth and characterization of Te- and Zn-doped InGaP layers are described. The strongest photoluminescence peak intensity occurs at 1×1018 and 6×1017 cm-3 for electron and hole concentrations, respectively. Diodes fabricated from the p-n homostructure are characterized by current-voltage measurement, electroluminescence, light output power, and external quantum efficiency. A forward-bias turn-on voltage of 1.5 V with an ideality factor of 2.02 and a breakdown voltage as high as 20 V are obtained from the current-voltage measurements. The emission peak wavelength and the full width at half-maximum of electroluminescence are around 5840 Å and 66-55 meV at 20 mA, respectively. The light output power of the uncoated diodes is about 35 µW at a dc current of 100 mA, and an external quantum efficiency of ∼0.02% is observed. The EL spectra are compared to the PL spectra of the Zn-doped InGaP layer at 300 and 50 K.

Al0.28Ga0.72As0.62P0.38 epitaxial layers were grown on GaAs0.61P0.39 substrates by liquid-phase epitaxy using a supercooling technique. The growth conditions and properties of the undoped AlGaAsP layers are described in detail. A fairly shiny surface and a flat AlGaAsP-GaAsP heterointerface was obtained in our study. The lattice mismatch normal to the wafer surface between the Al0.28Ga0.72As0.62P0.38 layer and GaAs0.61P0.39 substrate is ∼+0.27%. Low-electron-concentration undoped epitaxial layers can be grown from a Ga solution baked at a temperature of 900°C for 10 h or more and with a ∼6°C supersaturation temperature. We obtained the lowest electron concentrations of 1×1016 cm-3 measured by the capacitance-voltage method. By the photoluminescence measurements at various temperatures and excitation levels, the four recombination peaks observed are associated with the near-band-to-band, donor-to-valence-band, conduction-band-to-acceptor and donor-to-acceptor-pair transitions. The band gap of the Al0.28Ga0.72As0.62P0.38 is ∼2.016 eV (6150 Å). The binding energy of the donor and acceptor is 14 and 36 meV, respectively.

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