tailieunhanh - báo cáo hóa học: " Catalytic growth of ZnO nanostructures by r.f. magnetron sputtering"

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: Catalytic growth of ZnO nanostructures by . magnetron sputtering | Arroyo-Hernández et al. Nanoscale Research Letters 2011 6 437 http content 6 1 437 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Catalytic growth of ZnO nanostructures by . magnetron sputtering María Arroyo-Hernandez Raquel Álvaro Sheila Serrano and José Luis Costa-Kramer Abstract The catalytic effect of gold seed particles deposited on a substrate prior to zinc oxide ZnO thin film growth by magnetron sputtering was investigated. For this purpose selected ultra thin gold layers with thicknesses close to the percolation threshold are deposited by thermal evaporation in ultra high vacuum UHV conditions and subsequently annealed to form gold nanodroplets. The ZnO structures are subsequently deposited by . magnetron sputtering in a UHV chamber and possible morphological differences between the ZnO grown on top of the substrate and on the gold are investigated. The results indicate a moderate catalytic effect for a deposited gold underlayer of 4 nm quite close to the gold thin film percolation thickness. Introduction Single crystalline zinc oxide ZnO nanowires are usually grown by wet chemical and vapour transport methods. The latter are performed at temperatures in the 850 to 1400 C range 1 2 . Lower temperature 400 C metalorganic vapour-phase epitaxial growth of vertically well-aligned ZnO nanorods has been also reported in 3 . Another kind of nanowires Si and GaAs are grown by vapour-liquid-solid deposition VLS using gold nanoparticle catalysts 4 5 . Notably III to V nano-whiskers have been grown on III to V substrates by metalorganic chemical vapour deposition MOCVD 6 7 . This approach relies on annealing a thin Au film to form the seed particles 8 . In this way a homogeneous whisker width distribution is obtained the mean size of which could be controlled by the thickness of the Au layer and the way this layer transforms to nanoparticles. A similar approach to form ZnO nanostructures is reported herein .