ICMCTF 2012! - CD-Lab Application Oriented Coating Development

content. Analyses of the oxidised coatings by X-ray diffraction and Raman
spectroscopy revealed the formation of oxides, in the present case Cr2O3, at
a temperature of 800°C if Fe was present as compared to 900-1000°C for
the reference AlCrN coating.
Fundamentals and Technology of Multifunctional Thin
Films: Towards Optoelectronic Device Applications
Room: Pacific Salon 3 - Session C1-1
Recent Advances in Optical Thin Films
Moderator: K. Khajurivala, Janos Technology
Incorporated, US, R. Sczupak, Reynard Corporation, US
10:00am C1-1-1 Manipulation of Photons by Photonic Crystals, S.
Noda (snoda@kuee.kyoto-u.ac.jp), T. Asano, Kyoto University, Japan
INVITED
Photonic crystals are nanostructures for light with periodic refractive index
change. They look like periodic air-hole arrays in regular patterns. By
manipulating the patterns and developing two- or even three-dimensional
structures, various and flexible manipulations of photons become possible.
Our research has demonstrated that photonic crystals indeed allow to
manipulate photons almost on demand and could contribute to broad
applications including communication, information, storage, processing,
and even global energy issues.
For example, we have successfully demonstrated that photonic crystals can
produce photonic nano-devices with the sizes less than 1/100,000 of
conventional on-road devices while achieving excellent optical functions.
These devices are very useful to increase the amount of information in
optical communications. We have also shown that photonic crystals enable
a nanocavity (a cage of light), which can confine light very strongly. The
nanocavity can be used for slowing and even stopping light. In the present
optical signal processing, light signals are at first converted to electronic
signals to store the signals, and then re-converted to light signals. If we
could directly store light as it is, the speed of the signal processing could be
significantly increased. The nanocavity is also important for quantum
information processing and communication, which are considered as the
important candidates for the next generation communication and signal
processing.
Moreover, we have demonstrated that photonic crystals can produce an
unprecedented type of lasers, which cannot be achieved by the conventional
technologies. We found that the photonic-crystal lasers can oscillate in a
perfect single mode in a broad area and produce on-demand beam patterns
with desired characteristics. These results will lead to the realization of
various types of novel light sources; for example, a light source with
extremely high output powers, a super-resolution light source which can be
focused much smaller than the wavelengths, and a light source which can
trap and manipulate nontransparent materials such as small pieces of metals.
These light sources achieved by the photonic-crystal lasers should be very
important for laser processing systems, next generation DVD systems, and
versatile optical tweezers systems, etc.
Our works on photonic crystals will also contribute to address global energy
issues. Photonic crystals can manage light emission and detection, which
has great potentials to produce extremely high-efficient LEDs and solar
cells. These are very important to save huge energies for lightings, and also
to convert efficiently solar energy to electric one.
References:
(1) Noda, et al, Science 289, 604 (2000)., (2) Noda, et al, Nature 407, 608
(2000)., (3) Noda, et al, Science 293, 1123 (2001)., (4) Song, Noda, et al,
Science 300, 1537 (2003)., (5) Akahane, Noda, et al, Nature 425, 944
(2003)., (6) Asano, Noda, Nature 429, doi:10.1038 (2004)., (7) Ogawa,
Noda, et al, Science 305, 227 (2004)., (8) Fujita, Noda, et al, Science
308,1296 (2005)., (9) Song, Noda, et al, Nature Materials 4, 207 (2005).,
(10) Miyai, Noda, et al, Nature 441, 946 (2006)., (11) Noda, Science 314,
260 (2006)., (12) Noda, et al, Nature Photonics 1, 449 (2007)., (13) Song,
Noda, et al, Nature Materials 6, 862 (2007)., (14) Matsubara, Noda, et al,
Science 319, 445 (2008)., (15) Noda, Fujita, Nature Photonics 3, 129
(2009)., (16) Ishizaki, Noda, Nature 460, 367 (2009)., (17) Takahashi,
Noda, et al, Nature Materials 8, 721 (2009)., (18) Kurosaka, Noda, et al,
Nature Photonics, 4, 447 (2010).
10:40am C1-1-3 Phase transformation, structures and properties of
pure and carbon containing titania thin films annealed in air and in
hydrogen, W.C. Lee, M. Wong (mswong@mail.ndhu.edu.tw), National
Dong Hwa University, Taiwan
Pure titania (TiO2) and carbon containing titania(C-TiO2) thin films were
prepared by reactive sputtering titanium metal target and graphite target in
argon–oxygen plasma at 100 °C or below. The as-deposited thin films were
amorphous and subsequently annealed at various temperatures of 300~800
°C in air and H2 atmosphere. The effects of annealing on the thin films were
systematically studied in terms of phase transformation, activation energy,
crystallinity, oxygen vacancies and their optical and photocatalytic
properties. The as-deposited TiO2 transform to anatase at much lower
temperature than C-TiO2. At the same temperature, the H2-annealed films
achieve better crystallinity than the air-annealed. The activation energies of
phase transformation for amorphous to anatase were obtained and the
values are 126 and 47 KJ/mole for air- and H2-annealed pure TiO2,
respectively. The result shows that C-TiO2 need more energy for phase
transformation than pure-TiO2, and the H2 atmosphere was able to lower the
activation energy. Photocatalytic properties of these films were
characterized by degradation of methylene blue under irradiation of visible
light, and the C-TiO2 film annealed at 800°C in H2 possesses the best
performance.
11:00am C1-1-4 Effect of Laser Power on the Microstructure and
Photoluminescence of Silicon-rich Nitride Thin Films by Magnetron
Sputtering, C.K. Chung (ckchung@mail.ncku.edu.tw), C.H. Li, T.S. Chen,
Y.T. Lin, National Cheng Kung University, Taiwan
The silicon nanocrystals embedded in dielectric matrix has been extensively
studied due to quantum confinement effect and luminescence center for a
dramatic improvement of the light generation efficiency in Si nanostructure
for potential applications in Si-based optoelectronic integration circuit .
Beside, in order to form the Si nanocrystals, conventional furnace annealing
at high temperature (over 1000 ° C ) and sufficiently long time on the entire
sample leads to undesirable effects for device production in the post process
. In the article, the CO2 laser annealing method through local heating on
selected area was applied to produce Si nanocrystals from silicon-rich
nitride (SRN) thin films prepared by RF magnetron sputtering via the SRN
target. The various power of CO2 laser irradiation was used for studying the
evolution of micro structure and photoluminescence (PL) of SRN films.
Grazing Incidence X-ray Diffraction, Fourier transform infrared
transmittance spectra, energy dispersive spectroscopy, Transmission
electron microscopy, Raman and photoluminescence spectrum were utilized
to characterize the microstructure and PL behavior of films. The Si
nanocrystals in SRN films are obtained by focusing on sample at a laser
power of 6 W . A broad PL spectrum is observed and suggested the origins
from electro-hole pair recombination in Si nanocrystals or luminescence
center in the band tail. The relationship between the laser power,
microstructure and PL behavior of SRN films is discussed and established.
11:20am C1-1-5 ZnO light-emitting diodes and laser diodes, X.W. Sun
(exwsun@ntu.edu.sg), Nanyang Technological University, Singapore
INVITED
In this paper, we present our recent works on ZnO light-emitting devices
including homojunction nanorod light-emitting diodes, optically pumped
whispering-gallery-mode (WGM) lasing and electrically driven WGM
heterojunction laser diodes.
Firstly, by applying plasma immersion ion implantation to modify the
surface of ZnO nanorods grown from pure Zn and oxygen without catalyst,
we found that the electronic defects only reside on the surface. This makes
them easy to be doped to p-type. Then by ion implantation of As and P, we
realized efficient pure UV emitting LEDs. For optically pumped WGM
lasing, we clearly observed the evolution from spontaneous to stimulated
emission from ZnO disks. The lasing process has pronounced excitonic
signature, that is, inelastic exciton-exciton scattering. The observed lasing
modes match well with the theoretical values derived from WGM lasing.
The proof-of-concept sensing application based on ZnO WGM lasing is
also demonstrated. Lastly, we fabricated the ZnO microrod/GaN
heterojunction laser diode, the EL emission mechanism for this diode was
discussed. At the current 12 mA, the WGM lasing with distinct multiplemode
structure was realized. This study indicates that the hexagonal ZnO
microstructure is of potential in microlaser diodes.
3 Monday Morning, April 23, 2012