AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Monday Sessions
       Session NS1-MoM

Paper NS1-MoM9
Self-Assembly and Photoluminescence of CdSe Quantum Dots from Buffer-Layer-Assisted Growth

Monday, October 31, 2005, 11:00 am, Room 204

Session: Nanometer Scale Structures
Presenter: V.N. Antonov, University of Illinois at Urbana-Champaign
Authors: V.N. Antonov, University of Illinois at Urbana-Champaign
P. Swaminathan, University of Illinois at Urbana-Champaign
J.S. Palmer, University of Illinois at Urbana-Champaign
J.H. Weaver, University of Illinois at Urbana-Champaign
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Nano-particles of II-VI semiconductors (qantum dots) exhibit well-known size-dependent optical properties due to the quantum confinement of their charge carriers. The principal routes of their synthesis have been chemical and thus difficult to integrate with silicon technology. In this paper, we demonstrate that CdSe quantum dots can be self-assembled and delivered on almost any substrate with the help of buffer-layer-assisted growth (BLAG). In BLAG, physical vapor deposition of atoms or molecules on multilayers of van der Waals solids leads to spontaneous formation of clusters. Subsequent warm-up and desorption of the buffer causes the clusters to diffuse and aggregate into larger structures. The extent of this aggregation is controlled by the thickness of the buffer. Here, sub-monolayer depositions of CdSe on Xe buffers ranging from 4 to 35 ML result in formation of quantum dots ranging from small 2 nm clusters to extended ramified islands with typical branch width of 3 nm. The diffusivity of CdSe nano-particles on solid Xe is determined from the evolution of particle density with buffer thickness. The photoluminescence spectra of the CdSe dots are measured at 3 K, and their maxima shift through a large portion of the visible range with particle size. The spectra are analyzed in terms of the measured size distributions of the dots and the existing models of quantum confinement in CdSe. BLAG should be applicable for the synthesis of quantum dots of any II-VI semiconductor on almost any substrate.