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Báo cáo hóa học: " The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes | Alvi et al. Nanoscale Research Letters 2011 6 130 http www.nanoscalereslett.eom content 6 1 130 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access The origin of the red emission in n-ZnO nanotubes p-GaN white light emitting diodes N H Alvi Kamran ul Hasan Omer Nur Magnus Willander Abstract In this article the electroluminescence EL spectra of zinc oxide ZnO nanotubes p-GaN light emitting diodes LEDs annealed in different ambients argon air oxygen and nitrogen have been investigated. The ZnO nanotubes by aqueous chemical growth ACG technique on p-GaN substrates were obtained. The as-grown ZnO nanotubes were annealed in different ambients at 600 C for 30 min. The EL investigations showed that air oxygen and nitrogen annealing ambients have strongly affected the deep level emission bands in ZnO. It was concluded from the EL investigation that more than one deep level defect is involved in the red emission appearing between 620 and 750 nm and that the red emission in ZnO can be attributed to oxygen interstitials Oi appearing in the range from 620 nm 1.99 eV to 690 nm 1.79 eV and to oxygen vacancies Vo appearing in the range from 690 nm 1.79 eV to 750 nm 1.65 eV . The annealing ambients especially the nitrogen ambient were also found to greatly influence the color-rendering properties and increase the CRI of the as - grown LEDs from 87 to 96. Introduction Zinc oxide ZnO is a direct wide band gap 3.37 eV semiconductor. In recent years it has attracted the attention of the research community for a variety of practical applications due to its excellent properties combined with the facility of growing it in the nanostructure form. At present ZnO is considered to be a very attractive material because it combines semiconducting and piezoelectric properties and in addition it is transparent biocompatible and bio-safe. These unique properties of ZnO makes it as a promising candidate for the next generation of visible and ultra-violet UV light-emitting