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.

The photoluminescence spectra of N-implanted In0.32Ga0.68P epitaxial layers grown on GaAs0.61P0.39 substrates by liquid-phase epitaxy have been investigated at different annealing temperatures and times by the rapid thermal annealing technique. The nitrogen level is located ∼110 meV below the Γ-band minimum for the In0.32Ga0.68P crystal. The activation energy necessary to place N atoms into sites to form the N-isoelectronic trap is 0.47 and 0.48 eV in Ar and N2 ambients, respectively. The optimum post-implantation annealing condition to obtain the maximum isoelectronic trap emission intensity is at 800°C for 30-s duration in both Ar and N2 ambients.

Good wallty Ab.28G~.72Aso.62Po.38 layers lattice matched to GaAse61Po.39 epitaxial substrates were grown by liquid-phase epitaxy using a supercooling technique. By selection of the optimum growth condition, we can obtain the undoped layer with a low electron concentration of 1 X lOI cmm3. The four major emission peaks observed from the temperature dependence of photoluminescence of the undoped AlGaAsP layer can be identified as the near-band-to-band, donor-to-valence-band, conduction-band-to-acceptor, and donor-to-acceptor-pair transitions. The binding energies of the residual donor and acceptor are 14 and 36 meV, respectively. Effects of Te doping on electrical and optical properties have been examined. The donor ionization energy of Te in the AlGaAsP layer is identified as 24.3 meV. Finally, a p-I&,32Gac6sP/ nAb ,2sG~,72Aso,62Po,3s single heterostructure diode was fabricated, which exhibits a forward-bias turn-on voltage of 1.6 V and an ideality factor of 2.24.