* Corresponding author. Fax: #1 617 258 8224; e-mail: kfjensen@mit.edu. Journal of Crystal Growth 195 (1998) 564—568 Synthesis of CdSe quantum dot—ZnS matrix thin films via electrospray organometallic chemical vapor deposition J.R. Heine, J. Rodriguez-Viejo, M.G. Bawendi, K.F. Jensen*  Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA  Grupo de Fisica de Materiales I, Dpto. Fisica, Universidad Autonoma de Barcelona, Bellaterra 08193, Spain  Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA  Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Abstract A modified organometallic chemical vapor deposition technique is used to incorporate luminescing II—VI nanocrystals (NCs) into ZnS thin films. The NCs are synthesized in organic solution and consist of a CdSe core and ZnS shell. The ZnS matrix is deposited by OMCVD from diethyl zinc and hydrogen sulfide while the NCs are delivered to the film surface via electrospray. Varying the size of the CdSe NC core enables tunable emission from the blue to the red. The ZnS shell provides electronic and chemical passivation of the CdSe core improving its luminescence and thermal stability. The thin films exhibit room temperature photoluminescence (PL) and cathodoluminescence (CL) dominated by emission from the NCs. PL quantum efficiencies greater than 10% have been achieved. The dependence of thin film luminescence and microstructure on deposition temperature is studied using optical photoluminescence and X-ray diffraction. Particular emphasis is placed on the relationship between the host ZnS structure and the optical properties of the NC—ZnS composite thin film.  1998 Elsevier Science B.V. All rights reserved. PACS: 78.55.Et; 78.60.Hk; 78.66.Hf; 81.15.Gh Keywords: Nanocrystals; Electrospray; ZnS; CdSe; Thin film composite 1. Introduction A single material that can provide luminescence across the visible spectrum would be useful for a wide range of applications including flat-panel displays, full-color LED displays, and efficient white light emission. A film comprised of quantum dots (QDs) embedded in a host matrix promises to be such a material. A quantum dot, being smaller than the bulk Bohr radius of an exciton, possesses discretized electronic states leading to a band gap that is greater than that of the bulk semiconductor. By changing the size of the quantum dot the effec- tive bandgap can be changed. This variability of the band gap enables tuning of its absorption and emission spectra. For example, CdSe nanocrystals (NCs) can be synthesized with diameters ranging 0022-0248/98/$ — see front matter  1998 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 0 2 4 8 ( 9 8 ) 0 0 6 4 6 - 0