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Research into the use of II-IV semiconductor quantum structures as optoelectronic devices is presented.

Networks consisting of one-dimensional ZnO nanowires and two-dimensional ZnO nanowalls were synthesized using a catalyst-free low-temperature approach. The size of the nanostructure was much smaller than that obtained by the previous catalyst-assisted method. The nanostructures exhibited stable excitonic states at room temperature, and emission due to exciton-exciton scattering was observed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The temperature-dependent exciton peak energy as well as intensity quenching due to overlapping of FX and D(super 0)X (donor-bound exciton) bands is addressed with an inclusion of donor-bound exciton-like defects. The D(super 0)X linewidth of ~8 meV exhibited the thermal activation energy of ~16 meV, closely consistent with the exciton-defect binding energy.

Abstract: Second-harmonic generation (SHG) from a Mg0.05Zn0.95O/Mg0.4Zn0.6O multilayers fabricated by the metalorganic chemical vapor deposition (MOCVD) technique was carried out. By comparing the second-harmonic signal generated in three kinds of sample, ZnO, Mg0.4Zn0.6O film and Mg0.05Zn0.95O/Mg0.4Zn0.6O multilayers, deposited at the same temperature and having almost the same thickness, we concluded that a significant enhancement of the second-harmonic signal can be achieved in Mg0.05Zn0.95O/Mg0.4Zn0.6O multilayers. The second-order susceptibility tensor χ zzz (2)=21.2 pm/V was deduced from a multilayer structure deposited at 300 °C with a total thickness of ∼1 μm, which is about two times greater than that of ZnO and Mg0.4Zn0.6O films. [Copyright &y& Elsevier]

Abstract: Mg x Zn1− x O/Mg y Zn1− y O multilayers were fabricated by metalorganic chemical vapor deposition (MOCVD) technique and second-harmonic generation (SHG) was carried out by the Maker fringe technique. By comparing the second-harmonic signal generated in ZnO film and Mg0.05Zn0.95O/Mg0.4Zn0.6O multilayers with the same deposition temperature and total thickness, we concluded that a significant enhancement of second-harmonic signal can be achieved in multilayer structure. The second-order susceptibility tensor was deduced from Mg0.05Zn0.95O/Mg0.4Zn0.6O multilayers deposited at 425°C with a total thickness ∼1μm, which was about 2 times that of ZnO film. [Copyright &y& Elsevier]

Abstract: ZnO nanocrystallite films were grown on pyrex by metalorganic chemical vapor deposition (MOCVD). X-ray diffraction (XRD) measurements revealed that the film was grown with ZnO (0001) surfaces parallel to the substrate. Optical transition due to free excitons was observed from both absorbance and photoluminescence (PL) measurements. The film also showed strong second harmonic generation (SHG). These results demonstrate the high quality of such films. [Copyright &y& Elsevier]

ZnO tubes were epitaxially grown on sapphire (0001) substrates by metalorganic chemical vapor deposition. The tubes grew along the substrate normal and were characterized by hexagon-shaped cross sections. All of the tubes possessed the same epitaxial relationships with respect to the substrate. Both reactor pressure and growth temperature were found to play an important role in the formation of ZnO tubes. Spiral column growth mode was found to be responsible for the formation of ZnO tubes. [ABSTRACT FROM AUTHOR]