tailieunhanh - Báo cáo hóa học: " Tunable Visible Emission of Ag-Doped CdZnS Alloy Quantum Dots"

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: Tunable Visible Emission of Ag-Doped CdZnS Alloy Quantum Dots | Nanoscale Res Lett 2010 5 96-102 DOI S11671-009-9449-9 NANO EXPRESS Tunable Visible Emission of Ag-Doped CdZnS Alloy Quantum Dots Ruchi Sethi Lokendra Kumar Prashant K. Sharma A. C. Pandey Received 15 July 2009 Accepted 24 September 2009 Published online 13 October 2009 to the authors 2009 Abstract Highly luminescent Ag-ion-doped Cd1-xZnxS 0 x 1 alloy nanocrystals were successfully synthesized by a novel wet chemical precipitation method. Influence of dopant concentration and the Zn Cd stoichiometric variations in doped alloy nanocrystals have been investigated. The samples were characterized by X-ray diffraction XRD and high resolution transmission electron microscope HRTEM to investigate the size and structure of the as prepared nanocrystals. A shift in LO phonon modes from micro-Raman investigations and the elemental analysis from the energy dispersive X-ray analysis EDAX confirms the stoichiometry of the final product. The average crystallite size was found increasing from to nm with gradual increase in Ag doping. It was observed that photoluminescence PL intensity corresponding to Ag impurity 570 nm relative to the other two bands 480 and 520 nm that originates due to native defects enhanced and showed slight red shift with increasing silver doping. In addition decrease in the band gap energy of the doped nanocrystals indicates that the introduction of dopant ion in the host material influence the particle size of the nanocrystals. The composition dependent bandgap engineering in CdZnS Ag was achieved to attain the deliberate color tunability and demonstrated successfully which are potentially important for white light generation. Keywords Alloy Nanocrystals Photoluminescence Raman spectroscopy R. Sethi L. Kumar El P. K. Sharma A. C. Pandey Nanophosphor Application Centre Physics Department University of Allahabad Allahabad 211 002 India e-mail lkumarau@ Introduction II-VI compound semiconductor nanocrystals have been paid great .