tailieunhanh - Báo cáo hóa học: " High degree of polarization of the near-bandedge photoluminescence in ZnO nanowires"

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: High degree of polarization of the near-bandedge photoluminescence in ZnO nanowires | Jacopin et al. Nanoscale Research Letters 2011 6 501 http content 6 1 501 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access High degree of polarization of the near-bandedge photoluminescence in ZnO nanowires 1 1 1 12 Gwenole Jacopin Lorenzo Rigutti Andres De Luna Bugallo Franpois Henry Julien Camilla Baratto Elisabetta Comini2 Matteo Ferroni2 and Maria Tchernycheva1 Abstract We investigated the polarization dependence of the near-band-edge photoluminescence in ZnO strain-free nanowires grown by vapor phase technique. The emission is polarized perpendicular to the nanowire axis with a large polarization ratio as high as at K and at 300 K . The observed polarization ratio is explained in terms of selection rules for excitonic transitions derived from the k-p theory for ZnO. The temperature dependence of the polarization ratio evidences a gradual activation of the XC excitonic transition. PACS . Keywords zinc oxide nanowire photoluminescence polarization Introduction One-dimensional nanoscale semiconductors have recently attracted considerable attention as promising candidates for innovative device applications. Their high surface to volume ratio can be exploited for the development of a new generation of chemical and biological sensors 1-3 . The wide bandgap eV of ZnO associated with its large exciton binding energy 60 meV also makes it one of the most promising materials for photonic devices such as light-emitting diodes 4 and lasers 5 . Thanks to the spatial separation of photogenerated carriers UV photodetectors with a very high photoconductive gain based on ZnO nanowires NWs have been demonstrated 6 . It has been shown that the photodetection properties of ZnO NWs depend on the light polarization 7 . The photoluminescence of ZnO is typically composed of a near-band-edge NBE peak due to excitonic recombination and of a broad emission band in the visible range related .