Phonon Response in the Infrared Region to Thickness of Oxide Films Formed by Atomic Layer Deposition

$29.00 plus tax (Refund Policy)

Buy Article:

Abstract:

Experimental transmission infrared spectra of γ-Al2O3 and ZnO films are collected from heat-treated thin oxide films deposited with uniform thickness on Si(100) using atomic layer deposition. We show that the Berreman thickness, i.e. the upper limit for a linear relationship between oxide film thickness and phonon absorbance in the infrared region in transmission configuration, is a concept that applies to both transverse and longitudinal optical phonons. We find that for aluminum oxide films the Berreman thickness is 125 nm, and we estimate that it is around approximately 435 nm for zinc oxide films. Combining experiment and simulation, we also show that the Berreman thickness is the maximum distance allowed between interfaces for Snell's law and Fresnel's formulas to determine the optical properties in the infrared region and in transmission configuration for a layer system including an oxide film. Below the Berreman thickness, a Taylor series expansion of the absorbance coefficient determines the linear relationship between phonon absorbance and oxide film thickness t, so that as t → 0 absorption Ap ∞ 4πωph t, where ωph indicates optical phonon frequency. Above the Berreman thickness, field boundary conditions at the air/oxide film interface effectively contribute with a single interface in explaining optical phonon absorbance. Preliminary infrared spectra in reflection configuration for γ-Al2O3/Si(100) are discussed, and the obtained data support the conclusions reported for the transmission configuration.

Keywords: ATOMIC LAYER DEPOSITION; BERREMAN EFFECT; INFRARED SPECTROSCOPY; OPTICAL PHONONS; THIN OXIDE FILMS; TRANSMISSION

Document Type: Research Article

DOI: http://dx.doi.org/10.1366/000370210790571954

Affiliations: 1: North Carolina State University, Department of Chemical and Biomolecular Engineering, 911 Partners Way, Centennial Campus, Raleigh, North Carolina 27695; James Madison University, Department of Physics and Astronomy, 901 Carrier Drive, Harrisonburg, VA 22807 2: North Carolina State University, Department of Chemical and Biomolecular Engineering, 911 Partners Way, Centennial Campus, Raleigh, North Carolina 27695

Publication date: January 1, 2010

More about this publication?
Related content

Tools

Favourites

Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more