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Abstract: A co-activating route was employed to fabricate ZnO light-emitting diode (LED) by using molecular beam epitaxy. N2 was used as the acceptor dopant source and O2 was used as assistant gas for N2 decomposing more than only oxygen source. Emission spectra of the N2+O2 mixture plasma were monitored in situ in order to adjust growth parameters timely. Under the assistance of O2, N atoms content in the plasma of the mixture shows a significant increase compared to the case without O2 assistance. Electrical measurements of the as-grown p-type ZnO on sapphire show a carrier concentration of 1.2×18cm−3 and a mobility approaching 1cm2 V−1 s−1. A ZnO LED was fabricated by depositing undoped n-type ZnO on the p-type layer. The turn-on voltage at 100K is about 3.70V, which approaches the bandgap of ZnO. Electroluminescence spectra show two bands: one is centered at 423 and the other centered at 523nm, respectively. [Copyright &y& Elsevier]

Abstract: We report the effects of gel composition and crystallization condition on the hydrothermal synthesis of optical-clear large AlPO4-5 crystals. By using a gel with excessive Al species and high HF content, large perfect hexagonal-shaped AlPO4-5 crystals (size 1.25mm×0.65mm) were obtained, at a synthesis temperature of 453K with a crystallization period of 36h. The optical quality of the crystals is sensitive to the crystallization temperature and time duration. [Copyright &y& Elsevier]