Abstract/Details

Ellipsometric characterization of gold/dielectric nanocomposite films

Dalacu, Dan.   Ecole Polytechnique, Montreal (Canada) ProQuest Dissertations Publishing,  2001. NQ60932.

Abstract (summary)

An optical characterization methodology has been developed to characterize the detailed microstructural characteristics of metal/dielectric nanocomposite thin films. The characterization is based on parametric models of the optical response of the nanocomposite systems applied to spectro-ellipsometric and spectro-photometric optical data. The modeling consists of effective medium approaches in combination with a modified Drude response to describe the metal and a Cauchy/Urbach response to describe the dielectric. The methodology was applied to gold particles in the size range 3 to 30 nm embedded in and deposited on different dielectric materials. The films were fabricated using hybrid approaches consisting of magnetron sputtering of the gold and plasma enhanced chemical vapour deposition (PECVD) of the dielectric, in particular, plasma-polymerized fluorocarbon (PPFC) and hydrogenated amorphous silicon dioxide (SiO2 :H).

Two important factors are critical in regard to the feasibility of such a characterization methodology: (i) the sensitivity of the optical constants of nanocomposite materials to the microstructure arising from the excitation of collective conduction electron oscillations, so-called surface plasmons, and (ii) the inherent sensitivity of ellipsometric measurements to the optical constants of thin films, combined with the constraints imposed on the optical model by taking spectroscopic measurements at multiple angles of incidence, and by including transmission spectra in the analysis. These two factors make possible the use of fitting procedures to extract either optical or microstructural parameters.

Two limiting particle sizes were identified: (i) for particles larger than 20 nm phase retardation and scattering become significant, marking the limit of the quasi-static approximation, and (ii) for particles less than 10 nm changes in the inter-band optical constants of gold become significant, marking the limit for which the bulk core response is applicable. In between these particle sizes, unprecedented agreement between the measured spectra and the effective medium model was obtained. This has allowed for two important observations: (i) a clear demonstration of dipole-dipole interaction effects seen with increasing particle concentration, and (ii) an accurate measure of the width of surface plasmon resonance as a function of particle size. (Abstract shortened by UMI.)

Indexing (details)


Subject
Optics;
Materials science
Classification
0752: Optics
0794: Materials science
Identifier / keyword
Applied sciences; Pure sciences; Dielectric; Gold/dielectric; Nanocomposite; Thin films
Title
Ellipsometric characterization of gold/dielectric nanocomposite films
Author
Dalacu, Dan
Number of pages
198
Degree date
2001
School code
1105
Source
DAI-B 62/08, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
978-0-612-60932-7
Advisor
Martinu, Ludvik
University/institution
Ecole Polytechnique, Montreal (Canada)
University location
Canada -- Quebec, CA
Degree
Ph.D.
Source type
Dissertation or Thesis
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
NQ60932
ProQuest document ID
304774934
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
https://www.proquest.com/docview/304774934/abstract