Nondestructive Depth Profiling of Optically Transparent Films by Spectroscopic Ellipsometry

2009 ◽  
pp. 392-392-5
Author(s):  
K Vedam ◽  
SY Kim ◽  
L D'Aries ◽  
AH Guenther
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Depth Profiling ◽  
Transparent Films ◽  
Optically Transparent

Depth Profiling in Diffusely Scattering Media Using Raman Spectroscopy and Picosecond Kerr Gating

2005 ◽  
Vol 59 (2) ◽  
pp. 200-205 ◽  
Author(s):  
P. Matousek ◽  
N. Everall ◽  
M. Towrie ◽  
A. W. Parker
Keyword(s):  
Depth Profiling ◽  
Depth Resolution ◽  
Disease Diagnosis ◽  
Excitation Wavelength ◽  
Raman Signal ◽  
Scattering Media ◽  
Pmma Layer ◽  
Photon Propagation ◽  
Laser Raman ◽  
Optically Transparent

We demonstrate how pulsed laser Raman excitation (∼1 ps) followed by fast optical Kerr gating (∼4 ps) can be used to effectively separate Raman signals originating from different depths in heterogeneous diffusely scattering media. The diffuse scattering slows down photon propagation through turbid samples enabling higher depth resolution than would be obtained for a given instrumental time resolution in an optically transparent medium. Two types of experiments on two-layer systems demonstrate the ability to differentiate between surface and sub-surface Raman signals. A Raman spectrum was obtained of stilbene powder buried beneath a 1 mm over-layer of PMMA (poly(methyl methacrylate)) powder. The signal contrasts of the lower stilbene layer and upper PMMA layer were improved by factors ≥5 and ≥180, respectively, by rejecting the Raman component of the counterpart layer. The ability to select the Raman signal of a thin top surface layer in preference to those from an underlying diffusely scattering substrate was demonstrated using a 100 μm thick optically transparent film of PET (poly(ethylene terephthalate)) on top of stilbene powder. The gating resulted in the suppression of the underlying stilbene Raman signal by a factor of 1200. The experiments were performed in back-scattering geometry using 400 nm excitation wavelength. The experimental technique should be well suited to biomedical applications such as disease diagnosis.

Beam size and collimation effects in spectroscopic ellipsometry of transparent films with optical thickness inhomogeneity

1996 ◽  
Vol 288 (1-2) ◽  
pp. 125-131 ◽  
Author(s):  
H. El Rhaleb ◽  
N. Cella ◽  
J.P. Roger ◽  
D. Fournier ◽  
A.C. Boccara ◽  
...  
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Optical Thickness ◽  
Beam Size ◽  
Transparent Films

Nondestructive depth profiling by spectroscopic ellipsometry

1985 ◽  
Vol 47 (4) ◽  
pp. 339-341 ◽  
Author(s):  
K. Vedam ◽  
P. J. McMarr ◽  
J. Narayan
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Depth Profiling

Nondestructive Depth-Profiling of Multilayer Structures by Spectroscopic Ellipsometry

MRS Bulletin ◽  
1987 ◽  
Vol 12 (1) ◽  
pp. 21-23 ◽  
Author(s):  
K. Vedam
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Monochromatic Light ◽  
Depth Profiling ◽  
Apple Computer ◽  
Multilayer Structures ◽  
Angle Of Incidence ◽  
Reflected Light ◽  
Detector Output ◽  
On Line ◽  
Proper Design

Spectroscopic ellipsometry (SE) is the newest nondestructive and nonperturbing technique for characterizing surfaces, interfaces, and multilayer structures. The technique was originally developed and perfected by Aspnes of Bell Laboratories and a commercial instrument is currently available. After a brief description of the basic principles involved in this technique, one of its many applications — the depth profiling of multilayer structures — is described. Further details about SE and its other applications can be found elsewhere.The automated spectroscopic ellipsometer that has been built in our laboratory is based on the design of Aspnes and Studna. A schematic diagram of the instrument is shown in Figure 1. It is basically a rotating analyzer ellipsometer operated by an on-line Apple computer, and it has spectroscopic scanning capability. Plane polarized monochromatic light is allowed to be incident on the sample at a chosen angle of incidence. The characteristics of the elliptically polarized reflected light is analyzed by a rotating analyzer. As Budde has shown, Fourier analysis of the detector output in a rotating analyzer ellipsometer yields the desired ellipsometric parameters Δ and ψ characterizing the material under study. Aspnes has pointed out that with proper design, alignment and operation, the precision attained is very high, and accuracy of the data is also as high as that attainable with null ellipsometers. The results of our own studies confirm these conclusions. Such measurements are carried out at a number of discrete wavelengths (˜100) distributed uniformly in the UV-visible-near IR spectral range.

Displays from Transparent Films of Natural Nanofibers

MRS Bulletin ◽  
2010 ◽  
Vol 35 (3) ◽  
pp. 214-218 ◽  
Author(s):  
Antonio Norio Nakagaito ◽  
Masaya Nogi ◽  
Hiroyuki Yano
Keyword(s):  
Thermal Expansion ◽  
Flexible Substrate ◽  
Cellulose Nanofibers ◽  
Organic Light Emitting Diodes ◽  
Flexible Displays ◽  
Light Emitting ◽  
Plastic Substrates ◽  
Transparent Films ◽  
Organic Light ◽  
Optically Transparent

AbstractOrganic light-emitting diodes bring a whole new level of image quality, power consumption, and very thin profiles to displays. In addition, with the appropriate choice of a flexible substrate, paper-like flexible displays that are lightweight, robust, and conformable can be produced. This will make it possible to roll or fold the displays for portability or incorporate them in clothing as wearable displays. Plastic substrates are considered prospective materials due to their inherent flexibility and optical qualities. However, one of the major drawbacks of plastics is the large thermal expansion. The thermal expansion of the substrate has to be compatible with those of the layers deposited on it, otherwise these layers will become strained and crack during the thermal cycling involved in the display manufacture. One of the proposed solutions to reduce the thermal expansion of plastics without appreciable loss in transparency is to reinforce them with nanofibers. These nanofibers are already available in enormous quantities in nature, in the form of cellulose, with the caveat that they have to be extracted properly. Here we present the methodologies required to obtain the cellulose nanofibers and to produce optically transparent composites for use in flexible displays.

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