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báo cáo hóa học:" White Electroluminescence Using ZnO Nanotubes/GaN Heterostructure Light-Emitting Diode"

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: White Electroluminescence Using ZnO Nanotubes/GaN Heterostructure Light-Emitting Diode | Nanoscale Res Lett 2010 5 957-960 DOI 10.1007 s11671-010-9588-z NANO EXPRESS White Electroluminescence Using ZnO Nanotubes GaN Heterostructure Light-Emitting Diode J. R. Sadaf M. Q. Israr S. Kishwar O. Nur M. Willander Received 8 March 2010 Accepted 19 March 2010 Published online 4 April 2010 The Author s 2010. This article is published with open access at Springerlink.com Abstract We report the fabrication of heterostructure white light-emitting diode LED comprised of n-ZnO nanotubes NTs aqueous chemically synthesized on p-GaN substrate. Room temperature electroluminescence EL of the LED demonstrates strong broadband white emission spectrum consisting of predominating peak centred at 560 nm and relatively weak violet-blue emission peak at 450 nm under forward bias. The broadband EL emission covering the whole visible spectrum has been attributed to the large surface area and high surface states of ZnO NTs produced during the etching process. In addition comparison of the EL emission colour quality shows that ZnO nanotubes have much better quality than that of the ZnO nanorods. The colour-rendering index of the white light obtained from the nanotubes was 87 while the nanorods-based LED emit yellowish colour. Keywords ZnO nanotubes Light-emitting diodes Electroluminescence Lightning White light sources Introduction Zinc oxide has substantive advantages including the quests for LEDs and laser diodes 1 2 because of its wide band gap 3.37 eV and large exciton-binding energy J. R. Sadaf M. Q. Israr S. Kishwar O. Nur M. Willander Department of Science and Technology ITN Linkoping University 60174 Norrkoping Sweden e-mail magwi@itn.liu.se 60 meV . Also deep level defects intrinsic and extrinsic in ZnO can lead to an emission band covering the whole visible spectrum 3 . Furthermore the optoelectronic properties of ZnO can be tuned by changing its morphology composition crystalline structure orientation and the growth conditions 4 5 . The development of ZnO homojunction .