AVS 47th International Symposium
    Surface Science Thursday Sessions
       Session SS1+MC-ThM

Paper SS1+MC-ThM2
Correlation of Electronic Structure with Photoluminescence Properties in Oxidized Silicon Nanoclusters

Thursday, October 5, 2000, 8:40 am, Room 208

Session: Oxide Applications and Oxidation
Presenter: J.A. Carlisle, Virginia Commonwealth University
Authors: J.A. Carlisle, Virginia Commonwealth University
I. Germanenko, Virginia Commonwealth University
Y. Pithawalla, Virginia Commonwealth University
M.S. El-Shall, Virginia Commonwealth University
Correspondent: Click to Email
The relationship between morphology, band-gap size, and photoluminescence data in surface-oxidized silicon nanoclusters is established using photon-yield measurements at the Advanced Light Source. After removal from the growth chamber, photoluminescence (PL) results indicate that as the clusters oxidize, the main PL peak moves from 1.83 eV to 1.94 eV in energy. The central focus of this work is to establish the origin of the PL peak, whether it arises due to quantum size effects or due to the formation of suboxides as the clusters oxidize. The changes in the morphology and bonding structure of the clusters were established using soft-x-ray fluorescence spectroscopy (SXF) and photon-yield near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, which probe the element-specific density of occupied (SXF) and unoccupied (NEXAFS) electronic structure. Our finding is that the as-synthesized nanoclusters consist of a pure, crystalline Si core within a nearly pure SiO2 shell. Very few suboxides are present, and the oxidation process does not lead to an increase in the amount of suboxides present within the particles. As the nanoclusters oxidize, the radius of the crystalline core decreases in size, which gives rise to the change in the position of the PL signal.