<p> This thesis is concerned with the improvement of the contrast ratio of flexible
display devices, which are Sphere Supported Thin Film Electroluminescent (SSTFEL)
devices. A two-layer coating system was selected as anti-reflection (AR) coatings to be
deposited on the surface of SSTFEL devices to reduce the reflection of the ambient light
from the surface of devices based on the interference concept. This AR coating was
composed of an ITO layer and an ultra-thin gold layer. In order to maximize destructive
interference in the visible wavelength range, the optical properties, including refractive
index, transmittance and reflection of ITO films and ultra-thin gold films related to
sputtering conditions have been studied. The electrical conductance of these two films
has also been explored because these two layers work not only as AR coatings but also as
a conductive and transparent electrode of SSTFEL devices. AFM images show that the
surface morphology of ultra-thin gold films on Si substrates is similar to that on an ITO
layer and on polypropylene sheets. The measurements of specular and diffuse reflectance
of AR coatings on the propylene sheets and devices have been performed in detail.
Results show that AR coatings have better performance on the devices when the
thickness of ultra-thin gold layers and ITO layers are 3.43 to 4.01nm, and 42.5 to 45.0nm
respectively. Specular and diffuse reflectance of SSTFEL devices with AR coatings are
around 1.3% and 13.6% respectively, which is 6.3 times less than that of devices without
AR coatings. The contrast ratio of devices with AR coatings is up to 47.9:1 at the ambient
illumination level of 52.6Lux. At the ambient illumination level of 200 Lux, the contrast ratio of SSTFEL devices is 5 times higher than that of SSTFEL devices without AR coatings. </p> <p> During the research on the properties of ultra-thin gold films, it has been observed that the ultra-thin gold film has unreported optical and electric properties when its thickness is around 3nm. Its reflectance spectrum is similar to the reflectance spectrum of the substrate, whether the substrate is a glass slide or a wafer of silicon, and follows the reflectance spectrum of the substrates with an increase of several percent in visible
wavelength range. The conductance of the ultra-thin gold film decreases by exponential decay as its thickness decreases for the conductance is based on tunneling effects. However, the conductance suddenly increases while the thickness of the ultra-thin gold layer is decreased at around 3 to 4 nm. This behavior has not been reported and explained. </p> / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22237 |
| Date | January 2006 |
| Creators | Shi, Yunxi |
| Contributors | Kitai, A. H., Engineering Physics |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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