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The development of a hybrid GaAs-aptamers biosensor for the label-free detection of adenosine 5'-triphosphate (ATP) is described. The results have shown the promise of prospective luminescence-based GaAs-aptamer biosensor that can be used in real-time sensing assays requiring a straightforward and efficient means of label-free analytical detection.

The structural and optical properties of GaAsP/GaP core-shell nanowires grown by gas source molecular beam epitaxy are examined by transmission electron microscopy, Raman spectroscopy, photoluminescence (PL), and magneto-PL. The effects of surface depletion and compositional variations in the ternary alloy are marked as a redshift in GaAsP PL upon surface passivation and a decrease in redshift in PL in the presence of a magnetic field due to spatial confinement of carriers.

X-ray photoelectron spectroscopy is used to study the annealing process of UV-ozone oxide on GaAs for the formation of gold nanoparticle. The UV-ozone oxide layer is found to contain [As.sub.2][O.sub.3] as dominant oxide, while the oxide layer becomes rich in [Ga.sub.2][O.sub.3] when annealed at 500 degree Celsius for 300 s in dry nitrogen environment.

The interfacial properties of lattice-matched InGaAs/InP superlattice (SL) structures grown by gas source molecular beam epitaxy are examined by high-resolution x-ray diffraction (HRXRD). The alternative model for InGaAs/InP SLs has accounted for grading in the interfacial layers and it is shown to be valid over a range of superlattice periods.

Abstract: Randomly oriented ZnO nanowire (NW) networks have been grown on thermal SiO2 substrates by the simple carbothermal reaction-assisted thermal evaporation of ZnO. One-dimensional growth was achieved with the aid of Au nanocluster catalysts dispersed on the substrates. The structures were studied by scanning electron microscopy, energy dispersive X-ray analysis, and X-ray absorption spectroscopy. The NW diameters and lengths were found to strongly depend on the substrate temperature (T S) and to be in the 5–10nm and 40–110nm ranges for T S =520°C, and in the 50–80nm and 1–3μm ranges for T S =700°C, respectively. The growth regime was characterized by comparing the NW structures obtained on SiO2 with those grown in the same deposition run on (100) Si substrates also covered with the Au catalyst. The NW structure prepared at 700°C behaves as a dense NW network with net electrical conductance and persistent photoconductance. These results suggest a method to deposit size-controlled ZnO NW networks on insulating cost-effective substrates with important potential applications as in chemical sensors and solar cells. [Copyright &y& Elsevier]