Low-Temperature Synthesis and Magnetic Characterization of Doped-ZnS Nanostructures
O. Perales-Pérez, S. Dussan Devia, M.S. Tomar, L.M. Morales, O. Mata and W. Jia
University of Puerto Rico, Mayaguez Campus, PR
chalcogenides, nanocrystalline thin films, spintronics, ZnS
Nanostructured DMSs are of great importance due to potential applications in spintronics and photo-electronic devices. Recent studies propose that ZnS doped with transition metal ions can exhibit ferromagnetic behavior at room temperature. The present work is focused on the synthesis of nanocrystalline powders and thin films of bare and transition metal (Cr, V, Mn)-doped ZnS, by chemical bath deposition (CBD). XRD analyses showed the coexistence of cubic and hexagonal ZnS phases. The average crystallite size was 5 nm. The absence of other XRD peaks suggested the incorporation of dopants in the host structure. AFM observations evidenced the homogenous deposition of the 200-nm thick sulfide films onto glass and quartz substrates. AFM images show the decrease in particle size when Cr ions co-existed in starting solutions. The size of the aggregates drops from 500nm (bare ZnS) down to 200nm in Cr-ZnS film with x = 0.05, where ‘x’ is the dopant fraction in starting solution. Each aggregate consisted of nanozise 50-nm individuals. Room-temperature SQUID measurements evidenced the incorporation of dopants into the ZnS. Depending on the type of dopant, ferromagnetic or paramagnetic behavior was observed. The dependence of magnetic and optical properties with composition and crystal size will also be discussed.
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Nanotech 2006 Conference Program Abstract