title: Lithography of self-assembled semiconductor quantum dots on templates fabricated from mixed Langmuir-Blodgett films.
abstract: In this paper, we discuss a useful technique to fabricate patterned single layers consisting of quantum dots on two-dimensional templates fabricated from phase-separated mixed Langmuir-Blodgett (LB) films. The phase-separated structures are governed by two competing interactions-line tension and dipole-dipole interaction-and are tunable by adjusting the intermolecular interactions between the film-forming molecules and the fabrication conditions. The templates can be fabricated from mixed LB films containing silane-coupling agents, which form covalent bonds with Si wafers. The CdS- or CdSe/ZnS-nanoparticles were immobilized on the templates using a chemisorption technique. The samples were analyzed using ultraviolet-visible absorption spectroscopy, emission spectroscopy, atomic force microscopy, scanning electron microscopy, and fluorescence microscopy. The diameters of the CdS-NPs and CdSe/ZnS were estimated to be about 2.6 and 4.5 nm, respectively, using the Brus equation. We successfully obtained a patterned single layer consisting of quantum dots on the templates. The density of the immobilized-CdSe/ZnS-NPs on these templates can be controlled through variations in the concentration of the aqueous dispersion of CdSe/ZnS-NPs. Fluorescence observations indicate that the immobilized-CdSe/ZnS-NPs on the templates serve as light-emitting devices. These results indicate that patterned quantum dots can be formed only through self-assembly processes.
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan. watasato@rs.noda.tus.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Naoya
authors.initials: N
authors.lastname: Tamura
authors.forename: Mutsuyoshi
authors.initials: M
authors.lastname: Matsumoto
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D008567:Membranes, Artificial; D053758:Nanoparticles / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D012666:Semiconductors; D013440:Sulfides / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D008567:Membranes, Artificial; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C034939:cadmium sulfide; C058667:cadmium selenide; C031238:zinc sulfide