Photoreflectance-derived band-gap parameters as a function of temperature for InGaAs and InAlAs lattice matched to InP are reported. The experiment was performed on a set of samples of various compositions (and strains) yielding greater reliability and ensuring self-consistency. For InGaAs, fits to the Varshni equation gave E0(T=0 K)=803 meV, α=4.0×10−4 eV K−1, and β=226 K. For InAlAs, E0(T=0 K)=1.541 eV, α=4.7×10−4 eV K−1, β=149 K, and Δ0=338 meV.

Photoluminescence from AlInAs/InP quantum wells and single heterojunctions is reported for the first time. An emission centered around 1.1 eV which is most intense in multiquantum well structures, is shown to originate from confined-particle transitions involving spatially separated electrons and holes in quantum wells in the InP and AlInAs, respectively. The AlInAs/InP heterostructure is shown to have a staggered band lineup with an effective band gap of 1.06 eV.

L91trolyte compositions in these experiments; lower r, values can be achieved by using a Ag-LSC cermet electrode 4' 11 or a different perovskite composition. 7.he present results show that r~ depended primarily on the YSB surface coverage. This is consistent with the present understanding of the reactions at stabilized Bi203 electrolytes; the rate-limiting steps, oxygen adsorption and surface diffusion, are believed to occur on the electrolyte surface rather than at the electrode surface. 5Finally, the application of the above results to SOFCs requires that the thin YSB layers are stable during long-term cell operation. The main limitation is that the layer be chemically stable with respect to the electrolyte and electrode, since mechanical strength and stability in fuel environments are not required. Furthermore, a close thermal expansion match to YSZ is not required for very thin layers? 6 In initial annealing experiments carried out at 750~ in air on LSC/YSB/YSZ samples with tys g = 50 nm, r~ values were stable over the period tested, 200 h. This suggests that the YSB did not interdiffuse and/or react with YSZ or LSC. Longer-term studies during SOFC operation are needed to prove that the YSB layers are sufficiently stable for SOFC applications.

High-quality InAlAs with excellent photoluminescence and low electron concentrations has been grown by organometallic vapor phase epitaxy (OMVPE). For InAlAs lattice matched to InP, electron concentrations as low as 7×1015 cm−3 and mobilities as high as 4472 cm2/V s at 300 K have been achieved. These values are comparable to results measured on material grown by liquid phase epitaxy and molecular beam epitaxy and exceed results for previously published OMVPE grown material. The variation of the structural, optical, and electrical properties of the InAlAs with lattice mismatch is reported.

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