GROWTH BY LIQUID-PHASE EPITAXY AND CHARACTERIZATION OF AL0.28GA0.72AS0.62P0.38

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 approximately +0.27%. Low-electron-concentration undoped epitaxial layers can be grown from a Ga solution baked at a temperature of 900-degrees-C for 10 h or more and with a approximately 6-degrees-C supersaturation temperature. We obtained the lowest electron concentrations of 1 x 10(16) 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 approximately 2.016 eV (6150 angstrom). The binding energy of the donor and acceptor is 14 and 36 meV, respectively.