PREPARATION OF II-VI QUANTUM-DOT COMPOSITES BY ELECTROSPRAY ORGANOMETALLIC CHEMICAL-VAPOR-DEPOSITION

New thin film composites consisting of a ZnSe matrix and CdSe nanocrys tals (NCs) have been prepared by a novel technique combining electrosp ray and organometallic chemical vapor deposition (OMCVD). CdSe NCs, sy nthesized in solution by controlled growth of CdSe nuclei, were deriva tized with pyridine or overcoated with a thin ZnSe layer. The derivati zed NCs were dispersed in a pyridine/ acetonitrile mixture and transfe rred into the growth zone of an OMCVD reactor using an electrospray. T he transferred NCs were co-deposited with ZnSe grown by OMCVD from hyd rogen selenide and diethyl zinc at temperatures ranging from 150 to 25 0 degrees C. The absorption and emission spectra of the composites sho w characteristic transitions of the NCs. The emission wavelength can b e tuned by selecting the size of the NCs. A pre-formed ZnSe passivatio n layer, also synthesized in solution, improves thermal stability of t he NCs during the co-deposition, and enhances the photoluminescence em ission efficiency of the composites. The elemental composition and mic rostructure of the materials are probed by Auger electron spectroscopy , X-ray fluorescence spectroscopy, and high-resolution transmission el ectron microscopy.