Optical functions of discontinuous aluminum films: Intraband and interband contributions to particle resonance absorption

Journal Article · Mon Mar 01 00:00:00 EST 1993 · Journal of the Optical Society of America, Part A: Optics and Image Science; (United States)

DOI:https://doi.org/10.1364/JOSAA.10.000515· OSTI ID:6608823

Nguyen, H V; Collins, R W ^[1]

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1. Pennsylvania State Univ., University Park (United States)

The authors have developed a comprehensive optical model that accounts for the continuous evolution of the effective optical functions of discontinuous Al (particle) films in the vicinity of the resonance absorption feature as a function of the particle size. They obtain unprecedented agreement between the calculated and experimental results for both real and imaginary parts of the effective dielectric functions of particle films that are from 1 to 6 nm in thickness. The experimental studies rely on a unique rapid-scanning multichannel ellipsometer to collect ([psi],[Delta]) spectra from 1.3 to 4.0 eV during Al particle-film growth by evaporation an sputtering onto SiO[sub 2]/c-Si substrates. In a least-squares regression analysis the effective dielectric functions that the authors obtained experimentally are fitted to a generalized Maxwell-Garnett effective-medium theory with three free parameters. Two parameters describe the particle-film morphology. The third parameter is the mean free path, which they assume to be common to electrons that participate in both intraband and interband transitions. From the modeling they find that the optical functions of the particles themselves are remarkably independent of size and shape as well as of the method of preparation. This is presumably because scattering at defects that are internal to the particles determines the electron relaxation time. The simplifying assumption regarding particle-film morphology (i.e., identical spheroids) does not appear to compromise these conclusions. From the overall study they conclude that the crystalline quality of substrate-supported metallic particles as small as 0.5 nm in radius can be assessed solely from noninvasive real-time spectroscopic ellipsometry measurements. 38 refs., 5 figs.

• OSTI ID: 6608823
• Journal Information: Journal of the Optical Society of America, Part A: Optics and Image Science; (United States), Vol. 10:3; ISSN 0740-3232
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
36 MATERIALS SCIENCE
ALUMINIUM
ELLIPSOMETRY
FILMS
MORPHOLOGY
METALS
OPTICAL PROPERTIES
PARTICLES
RESONANCE ABSORPTION
ELECTRONS
EXPERIMENTAL DATA
MEAN FREE PATH
OPTICAL MODELS
PARTICLE SIZE
REGRESSION ANALYSIS
RELAXATION TIME
SCATTERING
SPECTRA
SPHEROIDS
SPUTTERING
ABSORPTION
DATA
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
INFORMATION
LEPTONS
MATHEMATICS
MEASURING METHODS
NUMERICAL DATA
PHYSICAL PROPERTIES
SIZE
SORPTION
STATISTICS
661300* - Other Aspects of Physical Science- (1992-)
360104 - Metals & Alloys- Physical Properties