bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Features and Microwave Properties of Ba0.5Sr0.5TiO3 Films Grown on Sapphire Substrates
Authors: Cho Kwang Hwan , Ha Jong Yoon , Kang Chong Yun , Choi Ji Won , Lee Young Pak , Yoon Seok Jin
Published: March 2009

The change in dielectric constant of ferroelectric materials as a function of electric field is
the key to wide range of microwave application such as tunable filter, impedance matching network,
and phase shifter. In this study, ferroelectric Ba0.5Sr0.5TiO3 (BST) films were grown on r-cut sapphire
and polycrystalline sapphire (poly-sapphire) substrates by RF sputtering. The results of
comprehensive structural diagnostics of the films are correlated with the dielectric constant and
dielectric loss of a co-planar BST varactor, measured at a frequency range of 1~3 GHz. Textured BST
films approximately 500 nm thick, grown on r-cut sapphire substrates, are characterized by high
dielectric constant ≥ 650. However, polycrystalline BST films, grown on poly-sapphire substrates, are
less strained, having dielectric constant range of 430 ~ 640.
Electrical/Mechanical Properties of Porous Low-k Thin Films by Using Various Supramolecule Based Porogen
Authors: Yim Jin Heong , Park Young Kwon , Jeon Jong Ki
Published: March 2009

The porous SSQ (silsesquioxane) films were prepared by using alkoxy silyl substituted
cyclodextrin (sCD) and methyl substituted cyclodextrin (tCD) based porogen. The mechanical and
electrical properties of these deposited films were investigated for the applications as low dielectric
materials. The mechanical properties of porous film by using sCD are worse than those by using tCD
due to its high pore interconnection length. sCD templated porous films show almost constant pore
diameter as a function of porogen concentration due to strong linear polymerization of the sCD
molecules through polycondensation.
Electrical Switching Characteristics of Nitrogen Doped Ge2Sb2Te5 Based Phase Change Random Access Memory Cell
Authors: Kim Myoung Sub , Jun Jin Hyung , Oh Jin Ho , Kim Hyeong Joon , Roh Jae Sung , Hong Suk Kyoung , Choi Doo Jin
Published: March 2009

Ge2Sb2Te5 (GST) has been widely studied for PRAM as reversible phase change material.
GST is expected to reduce RESET (crystalline → amorphous) operation power, which is one of
important issues for PRAM technology. In order to investigate the effect of nitrogen doping on
electrical switching characteristics, we fabricated two kinds of PRAM cells with nitrogen-doped
(N-doped) and un-doped GST, which were different bottom electrode contact size (0.80~1.00 ).
N-doped GST PRAM cells have higher dynamic resistance with small sized bottom electrode contact
and lower RESET voltage (about 1.2 V, 50 ns) than un-doped GST PRAM cells (about 1.6 V, 50 ns).
The resistance switching ratio (RRESET to RSET) was about 100. The results of this study indicate that
nitrogen doping into GST film and smaller size of bottom electrode contact reduce RESET power for
PRAM operation.
The Growth of Transparent Conductive Al-Doped ZnO Thin Films at Room Temperature
Authors: Park Sang Moo , Tomemori Takashi , Ikegami Tomoaki , Ebihara Kenji
Published: March 2009

High-quality transparent conductive Al-doped ZnO (AZO) thin films were deposited by
pulsed laser deposition on quartz glass substrates at room temperature. We varied the growth
condition in terms of oxygen pressure. The structure and electrical and optical properties of the
as-grown AZO films were mainly investigated. The AZO films formed at room temperature showed a
low electrical resistivity of 3.01×10-4 ) cm, a carrier concentration of 1.12×1021 cm-3 and a carrier
mobility of 18.59 cm2/Vs at an oxygen pressure of 10 mTorr. A visible transmittance of above 83%
was obtained. The present results suggest that optimized AZO films should be very useful and
effective for flexible display, top emission type of OLEDs and for various other kinds of
optoelectronic devices such as flexible solar cell or passive photo device.
Structural and Mechanical Properties of Low Dielectric Constant SiOC(-H) Films Using MTES/O2 Deposited by PECVD
Authors: Navamathavan R. , Zakirov Anvar , Kim Hyun Seung , Jang Yong Jun , Jung An Soo , Choi Chi Kyu
Published: March 2009

Low dielectric constant SiOC(-H) films were deposited on p-type Si (100) substrates by
plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES;
C7H18O3Si) and oxygen gas as precursors. The SiOC(-H) films were deposited at room temperature
and then annealed. Nanoindentation studies were carried out in order to determine the mechanical
properties of the SiOC(-H) films. The elastic modulus and hardness of SiOC(-H) films were
measured to be in the range of 2.14 – 5.02 and 0.12 – 0.74 GPa, respectively. It was observed that
the values of elastic modulus and hardness decreases with increase of flow rate ratio of the
precursors. In the SiOC(-H) film, -CH3 group as an end group was introduced into -O-Si-O- chain
network, thereby reducing the film density to decrease the values of the mechanical properties.
Effects of Firing Temperature and Film Thickness on the Critical Properties of YBCO Film by the '211 Process'
Authors: Lim Jun Hyung , Jang Seok Hern , Lee Seung Yi , Yoon Kyung Min , Kim Kyu Tae , Joo Jin Ho , Lee Hoo Jeong , Lee Hee Gyoun , Hong Gye Won
Published: March 2009

We fabricated by metal organic deposition (MOD) using trifluoroacetic acid (TFA) via the
“211 process”, and then evaluated the phase formation, texture evolution, and critical properties as a
function of the firing temperature and film thickness. In the fabrication process, Y2Ba1Cu1Ox and
Ba3Cu5O8 powders were used as precursors instead of Y-, Ba- and Cu-based acetates. The films were
fired in the temperature range of 750°C -800°C and the film thickness of films was controlled by
repeating the number of coating cycles. The microstructure varied significantly with the firing
temperature. The grains size increased, the film became denser, and the degree of the texture and
phase purity varied with increasing firing temperature. The films fired at 775°C after calcining at
4005 showed the highest critical current (Ic) of 18 A/cm-width, which corresponds to a critical
current density (Jc) of 0.9 MA/cm2. For multi-coated films, the Ic increased from 18 in the singly
coated film to 100 A/cm-width with the triply coated film. In contrast, the corresponding Jc were in
the range of 0.9-1.2 MA/cm2. Both Ic and Jc values decreased as the coating number repeated further
as a result of the degraded microstructure.
Bump Formation and Flip Chip Processes for RF System-on-Packages
Authors: Jung Boo Yang , Choi Eun Kyoung , Jeon Young Soo , Lee Kwang Yong , Seo Kwang Seok , Oh Tae Sung
Published: March 2009

For flip-chip process of RF system-on-packages(SOP), double bump bonding processes
were investigated. Sn-Ag and Sn solder joints were formed by the reflowed double bumping process,
and Sn/In/Sn bump joints were fabricated by the non-reflowed double bump bonding process. The
height-to-size ratios of 0.78 and 0.65 were obtained for the reflowed double bumping and the
non-reflowed bumping, respectively. Average contact resistance of the reflowed Sn-Ag and Sn solder
joints was about 13m/ which was much lower than 24~33m/ of the non-reflowed Sn/In/Sn bump joints.
The reflowed solder double bumping method is more suitable for flip-chip process of RF-SOP than the
non-reflowed double bump bonding.
Microstructural Study on the Wear Behavior of Cu-TiB2 Composites for Electrical Contact Materials
Authors: Lee Tae Woo , Shin Chan Soo , Kang Kae Myung
Published: March 2009

We have studied on the wear behavior of Cu-TiB2 composites, produced by thermal
extraction, as a function of dispersed particle sizes and volume fractions of TiB2. The depth of
subsurface zone was increased with applied loads from 25 μm with 20 N to 25 μm with 80 N. From
the analyses results of the formation of wear debris generated by cracks between work hardened layer
and matrix, wear mechanism is changed from abrasive wear to adhesive wear with increasing loads
from 20 N to 80 N. The formation of sub-grains in the region of subsurface was clearly observed from
the sample tested over 60 N loads. We attribute the formation of sub-grains to the plastic lubricant
effect of TiB2 which gives arising from the contact stress and local heat generated during wear test.
Indium Tin Oxide Film Characteristics after Chemical Mechanical Polishing Process with Control of Pad Conditioning Temperature
Authors: Kim Nam Hoon , Choi Gwon Woo , Seo Yong Jin , Lee Woo Sun
Published: March 2009

Indium tin oxide (ITO) CMP was performed by change of de-ionized water (DIW)
temperature in pad conditioning process. DIW with high temperature was employed in pad
conditioning immediately before ITO-CMP. The removal rate of ITO thin film polished by silica
slurry immediately after pad conditioning process with the different DIW temperatures dramatically
increased to 93.0 nm/min after pad conditioning at DIW of 75 oC, while that after the general
conditioning process at 30 oC was about 66.1 nm/min. The grains of ITO thin film became
indistinguishable by CMP after pad conditioning with the high-temperature DIW. The carrier density
decreased with the increase of conditioning temperature. The hall mobility rapidly increased
regardless of conditioning temperature. The uniformity of optical transmittance also improved.
Formation of High Flux Parallel Neutral Beam Using a Three Grid System of Ion Beam during Low Angle Forward Reflection of Ions
Authors: Park Byoung Jae , Min Kyoung Seok , Park Sang Duk , Bae Jeong Woon , Vozniy Oleksiy , Yeom Geun Young
Published: March 2009

The energy and the flux of the ion gun with a three-grid system was compared with those of
the ion gun with a two-grid system and the characteristics of the neutral beam sources composed of
the ion guns with different grid systems and a reflector for the low angle reflection of the ions were
investigated. By using the three-grid system instead of the two-grid system and by applying higher
negative voltage to the 2nd grid, a higher ion flux without changing the ion energy could be obtained
for the ion gun of the neutral beam source. The three-grid ion gun system generated higher neutral
beam fluxes compared to the two-grid ion gun system. This result was confirmed by measuring the
etch rates of Si and GaAs with Ar and fluorine neutral beam. Also, using the neutral beam source with
the three-grid ion gun, 35nm-width Si patterns could be etched vertically by CF4 gas indicating the
formation of a parallel neutral beam.
The Effect of Bias Power on the Etching Rate and Uniformity of Silicon Dioxide for N-Slot Inductively Coupled Plasma in TFT Application
Authors: Wei Che Hung , Chen Yu Hung
Published: March 2009

The etching in SiO2 is a crucial step in fabricating thin film transistor. For large area
etching, high density plasma which independently controls ion energy and ion flux is preferable than
conventional RIE etcher for its high etching capability. In an attempt to understand how the bias
power of N-slot ICP affects the etching rate and uniformity, we study the correlation among bias
power, inductive power, etching rate and uniformity. The results show that the etching rate is
proportional to the bias power up to 800 W which has the best uniformity. Beyond that power, the
etching rate enters the different slope and the uniformity become worse. This phenomenon might be
attributed to the combined effects of resist etching and polymer film growth. For N-slot ICP system,
high etching rate and good uniformity can be obtained only when the bias power is in the moderate
range.
Ferroelectric P(VDF/TrFE) Ultrathin Film for SPM-Based Data Storage Devices
Authors: Lee Jong Soon , Kim Kap Jin , Prabu Arun Anand
Published: March 2009

In this paper, the surface crystalline morphology and piezoelectricity of
P(VDF/TrFE)(72/28) copolymer ultrathin films were studied using different scanning probe
microscopy (SPM) techniques. Atomic force microscopy (AFM) was used to study the changes in
their crystalline morphology with varying temperature conditions. From electric force microscopy
(EFM) studies, the change in dipole moment vectors along the applied field direction and the resultant
change in amplitude image for '1 or 0' state were monitored and used to 'write/erase and read' the data
on the memory bit. These results indicate the possibility of using SPM-based high density data storage
with these copolymer ultrathin films.
Effect of Cu Dopant on the Electrical Property of ZnO Thin Films Deposited by Pulsed Laser Deposition
Authors: Kim Gun Hee , Kang Hong Seong , Kim Dong Lim , Chang Hyun Woo , Ahn Byung Du , Lee Sang Yeol
Published: March 2009

Cu-doped ZnO (denoted by ZnO:Cu) films have been prepared by pulsed laser deposition
using 3 wt. CuO doped ZnO ceramic target. The carrier concentrations (1011~1018 cm-3) and, electrical
resistivity (10-1~105 cm) of deposited Cu-doped ZnO thin films were varied depending on
deposition conditions. Variations of electrical properties of Cu-doped ZnO indicate that copper
dopants may play an important role in determining their electrical properties, compared with undoped
films. To investigate effects of copper dopants on the properties of ZnO thin films, X-Ray diffraction
(XRD), photoluminescence (PL), and Hall measurements have been performed and corresponded.
Behavior of Various Organosilicon Molecules in PECVD Processes for Hydrocarbon-Doped Silicon Oxide Films
Authors: Yun Yong Sup , Yoshida Takanori , Shimazu Norifumi , Inoue Yasushi , Saito Nagahiro , Takai Osamu
Published: March 2009

Plasma diagnosis was performed by means of optical emission spectroscopy in the
plasma-enhanced chemical vapor deposition process for preparation of hydrocarbon-doped silicon
oxide films. The chemical bonding states were characterized by a fourier-transform infrared
spectrometer. Based on the results of the diagnosis in organosilane plasma and the chemical
bonding states, a reaction model for the formation process of hydrocarbon-doped silicon oxide films
was discussed. From the results of optical emission spectroscopy, we found that the oxygen atoms
of methoxy groups in TMMOS molecules can be dissociated easily in the plasma and behave as a
kind of oxidizing agent. Siloxane bondings in HMDSO, on the other hand, hardly expel oxygen
atoms.
Cobalt Thin Film Deposited by Remote Plasma Atomic Layer Deposition Method Using C12H10O6(Co)2 and CpCo(CO)2
Authors: Lee Keun Woo , Kim Keun Jun , Jeong Woo Ho , Park Tae Yong , Jeon Hyeong Tag
Published: March 2009

Co thin films were deposited by remote plasma atomic layer deposition (ALD) method
using dicobalt hexacarbonyl t-butylacetylene (C12H10O6(Co)2) or cyclopentadienyl cobalt
dicarbonyl (CpCo(CO)2) as the Co precursor. The impurity contents were minimized when the Co
films deposited by remote plasma ALD with H2 plasma within the process pressure range of
0.1~2 Torr at plasma power of 300W. Co-Cp bond in CpCo(CO)2 precursor was easily broken
under H2 remote plasma atmosphere. The carbon content of Co films were examined with Auger
electron spectroscopy (AES) and Rutherford backscattering spectroscopy (RBS) to be ~21 at.%
with C12H10O6(Co)2, and ~7 at.% with CpCo(CO)2. The surface morphologies of Co films were
measured with atomic force microscope (AFM) and root mean square (RMS) values of Co films
using C12H10O6(Co)2 and CpCo(CO)2 were 1.73 and 1.51, respectively.
Properties of ITO Films Deposited on Plastic Substrate by RF Superimposed DC Magnetron Sputtering Method
Authors: Kim Do Geun , Lee Sung Hun , Park Mi Rang , Jeong Yu Jeong , Lee Gun Hwan , Song Pung Keun
Published: March 2009

Tin doped indium oxide (ITO) films were deposited on plastic films by RF superimposed
DC magnetron sputtering method using an In2O3 – 10 wt.% SnO2 target without intentionally heating
substrates. We have investigated the effects of an RF superimposed DC power system on the
electrical, optical, and mechanical properties of the ITO films by using Four-Point Probe, Hall Effect
Measurement, UV-Vis-NIR Spectrophotometer, XRD, and Residual Stress Measurement. With
increasing the amount of RF power superimposed on DC power, the sputtering discharge voltages of
DC power supply were decreased from –290 V to –100 V, i.e., plasma impedance decreased with an
increase of the amount of RF power. The resistivity of the samples drastically decreases with
increasing RF power, and shows the lowest value of 3.8×10-4 8·cm. Hall effect measurements explain
that the increase of carrier mobility is strongly related with the enhancement of the resistivity of ITO
films even though there is no difference on its concentration. The RF power superimposed on DC
power also reduces the residual stress of the samples up to the stress level of ~ 200 MPa at optimum
values of RF power.
Pentacene Organic Thin-Film Transistors with Dual-Gate Structure
Authors: Koo Jae Bon , Lim Jung Wook , Ku Chan Hoe , Lim Sang Chul , Lee Jung Hun , Kim Seong Hyun , Yun Sun Jin , Yang Yong Suk , Suh Kyung Soo
Published: March 2009

We report on the fabrication of dual-gate pentacene organic thin-film transistors (OTFTs)
using a plasma-enhanced atomic layer deposited (PEALD) 150 nm thick Al2O3 as a bottom gate
dielectric and a 300 nm thick parylene or a PEALD 200 nm thick Al2O3 as both a top gate dielectric
and a passivation layer. The threshold voltage (Vth) of OTFT with a 300 nm thick parylene as a top
gate dielectric is changed from 4.7 V to 1.3 V and that with a PEALD 200 nm thick Al2O3 as a top gate
dielectric is changed from 1.95 V to -9.8 V when the voltage bias of top gate electrode is changed
from -10 V to 10 V. The change of Vth of OTFT with the dual-gate structure has been successfully
understood by an analysis of electrostatic potential.
Spherical BaMgAl10O17:Eu2+ Phosphor Particles by Liquid Phase Synthesis
Authors: Jung Ha Kyun , Lee Dae Won , Park Yoon Chang
Published: March 2009

To improve luminescent properties of the phosphor, spherical BaMgAl10O17:Eu2+ particles
have been synthesized using a liquid phase reaction composed of two-stage precipitations. This
phosphor particles exhibited uniform size (0.4 ㎛) with narrow distribution and were well-dispersed
without agglomeration. The single phase of phosphor was formed by firing at the temperature of
about 1350°C. The preparation conditions in this synthetic process for spherical BaMgAl10O17:Eu2+
particles were optimized on the basis of emission intensity by the excitation at 147 nm. The emission
spectra showed the typical broad band due to the transition of Eu2+ activator from 4f65d1 to 4f7 in
BaMgAl10O17:Eu2+. The maximum emission intensity for this spherical blue phosphor was obtained
by reduction treatment at 1450°C.
Characteristics of TAG:Ce Phosphor Particles Prepared by Ultrasonic Spray Pyrolysis
Authors: Hong Seung Kwon , Koo Hye Young , Ju Seo Hee , Kang Yun Chan
Published: March 2009

Tb3Al5O12:Ce (TAG:Ce) phosphor particles were prepared by spray pyrolysis process.
The TAG:Ce phosphor particles prepared by spray pyrolysis had good characteristics such as fine
size, narrow size distribution, and high photoluminescence intensity under blue light excitation. The
TAG:Ce phosphor particles had the maximum photoluminescence intensity after post-treatment at
1550oC under reducing atmosphere. The photoluminescence intensity of the prepared TAG:Ce
phosphor particles was 85% of the optimized YAG:Ce phosphor particles.
ITO Contact Properties with Amorphous Silicon for AM-OLED Application
Authors: Jeon Jae Hong , Choe Hee Hwan , Seo Jong Hyun
Published: March 2009

In order to improve long term stability of a-Si:H TFT for AM-OLED application a new
driving method compensating Vth shift requires a new device structure of which hole injection is
enhanced. ITO film was investigated for the hole injection material because it is essential material for
display devices and has high work function favorable for hole injection. From I-V characteristics of
TFTs with two types of source and drain material, i.e. Cr and ITO, the contact properties were
measured and compared. Although electron injection property of ITO was worse than Cr, hole
injection property was comparable to that of Cr.
Chemical Durability of Frits Used in Process of Plasma Display Panels
Authors: Hwang Seong Jin , Kim Yu Jin , Shim Seung Bo , Kim Hyung Sun
Published: March 2009

The chemical reaction between water and frit surface was determined using pH meter,
ICP-MS, zeta-potential analyzer and FT-IR. With increasing the content of barium and boron of glass
composition, the difference of water pH increased with different glass systems. During wet milling in
aqueous solution, boron and barium of glasses dissolved. The values of zeta potential of lead and
bismate frits were negative in water solution. Based on the results, when wet milling is used in water
solution, the contents of barium and boron in a glass should be less than 10mol%.
Properties of Polymer Light Emitting Diodes with Blue Color on ITO/Glass Substrates
Authors: Yoo Jae Hyouk , Gong Su Cheol , Baek In Jae , Lim Hyun Seong , Shin Sang Baie , Chang Young Chol , Chang Gee Keun , Chang Ho Jung
Published: March 2009

Polymer light emitting diodes (PLEDs) with ITO/PEDOT:PSS/PVK/PFO-poss/LiF/Al
structure were prepared by spin coating method on the plasma-treated ITO(indium tin oxide)/glass
substrates. PVK(N-vinylcabozole) and PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene
sulfolnate)] polymers were used as hole injection and transport materials. As blue light emitting
material, PFO-poss(poly(9,9-dioctylfluorence) polymer was used. The dependence of the plasma
treatment of ITO films on the optical and electrical properties of the PLEDs was investigated. The
sheet resistance of ITO films increased slightly with increasing the plasma intensity from 20W to
300W in RF power. In contrast, the surface roughness was improved as the plasma intensity increased.
The maximum current density and luminance were about 20 mA/cm2 and 250 cd/m2 at 9 V for the
PLED sample coated on ITO/glass substrate with plasma treatment of 100W for 30s under 40 mtorr
O2 pressure. The maximum emission spectrum of the PLEDs was 441 nm showing blue color.
Luminance Efficiency of a (La,Tb,Ce)PO4:Eu Phosphor Layer Prepared with Binary Surface Active Organic Molecules
Authors: Cha In Sung , Lee Jin Hyon , Paik Ung Yu , Yoon Seon Mi , Lee Eun Sung , Choi Jae Young
Published: March 2009

The effect of a binary surfactant on the luminance efficiency of a green phosphor was
investigated with an emphasis on the chemical control of interactions between the suspension
components. The dispersion system of the green phosphor paste was designed by an evaluation of the
acid and base properties of the green phosphor and the surface active organic molecules by a
non-aqueous titration method. Oleyl amine and 4-(1,1,3,3-tetramethylbutyl) phenyl-polyethylene
phosphoric acid (hereafter SAIT7) were added into the green phosphor paste taking into account the
ratio between the acid and base sites of the green phosphor particle’s surface. This resulted in a higher
maximum solid loading and a further decrease in the viscosity of the green phosphor paste compared
to a single addition of SAIT7 and oleyl amine. The green phosphor paste with the binary surfactant
exhibited a much improved photoluminescence intensity and homogeneity of the emission properties
than a single addition of the dispersant.
AEM Study on the Phase Transformation of Nickel Silicides in the Ni1-xTax/Si System
Authors: Lee J.W. , Yang Cheol Woong
Published: March 2009

We investigated the phase transformation and thermal stability of Ni silicides formed in
Ni/Si and Ni0.95Ta0.05/Si systems. The sheet resistance values of the silicide in the Ni0.95Ta0.05/Si
system were lower than those in Ni/Si system at any temperature. The enhancement of thermal
stability is closely related to the phase transformation occurred during post heat-treatment. Microstructure
of the phases formed by reaction was investigated by analytical electron microscopy (AEM)
and the phase identification of Ni silicide was carried out using convergent beam electron diffraction
(CBED) technique. It was found that a Ta rich layer formed on the top of the Ni silicide layer and
small amount of Ta dissolved into the silicide layer. By addition of Ta atoms, phase transformation
from NiSi to NiSi2 is retarded and thermal stability of Ni silicide is improved.
The Effects of SiO, SiON on IZO Thin Film Deposited by DCMG Method
Authors: Kim Seong Hoon , Yoon Han Ki , Murakami Riichi
Published: March 2009

The thin films of SiO and SiON were deposited individually by the inclination opposite
target type DC magnetron sputtering equipment onto the glass substrate. And it was deposited
IZO(In2O3 (90wt.%) + ZnO(10wt.%)) on those films. The effects of SiO and SiON were investigated
on properties of IZO thin films. AFM images of IZO thin film included SiON film were shown
smoother surfaces than that included SiO film. Multi layers of IZO were shown good properties
because it have high transmissivity. Resistivity is in inverse proportion to Mobility. If it deposited SiO
and SiON, generate layer of change between two layers(SiO or SiON + Substrate). Layer of change
influenced resistance because Oxygen content was more than single layer of IZO. In case of using
PET substrate, it influenced stronger than Glass substrate for rigid gas permeable and osmosis.
Synthesis and Fabrication of Novel Polymeric/Organic Materials for Micro/Nano-Scale Optical Printed Circuit Board and VLSI Photonic Integrated Circuit Application
Authors: Lee El Hang , Chin In Joo , Kwon Yong Ku , Lee S.G. , O B.H. , Park S.G. , Kim Kyong Hon
Published: March 2009

We report on the synthesis and fabrication of novel polymer/organic materials for
application for what we call optical printed circuit board (O-PCB) for VLSI photonic circuit
(VLSI-PIC). We synthesize copolymers containing cross-linkable pendant groups suitable for
embossing and novel device fabrication. We also synthesize organic-inorganic hybrid materials of
low optical absorption, good adhesion, low dielectric constant, high dielectric strength, high thermal
stability, excellent photo-patterning possibility and variability of refractive index. Steps of synthesis
and fabrication of these materials are described along with their optical, material, and performance
characteristics. O-PCB and VLSI photonic circuit design and fabrication processes are also presented.
Post-Annealing Effect of SiON Thin Film in Air
Authors: Lee Dong Bok , Yoon Dae Ho
Published: March 2009

About 2-thick, amorphous SiON thin films were deposited by the PECVD method, and
heated up to 1000oC in air to study the post-annealing effect on the composition and structure of the
SiON film. SiON had a strong SiO2 binding energy with a weak N-binding, so that air-annealing
resulted in nitrogen escape from the film. The inwardly transported oxygen from the atmosphere
was simply supersaturated inside the annealed, amorphous SiON thin film.
Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip
Authors: Choi Kyoung Jae , Park Joung Kyu , Kim Kyung Nam , Kim Chang Hae , Kim Ho Kun
Published: March 2009

We have synthesized a Eu2+-activated Sr3MgSi2O8 blue phosphor and (Sr,Ba)2SiO4 yellow
phosphor. We fabricated a phosphor-conversion white light emitting diode(LED) using an InGaN
chip that emits 400 nm near-ultraviolet(n-UV) light and phosphors that emit in the blue and yellow
region. When the white LED was operated at a forward-bias current of 20 mA at room
temperature(RT), the color temperature(Tcp), average color rendering(Ra), operating voltage(Vf) and
luminous efficacy(ηL) were estimated to be 5800K, 72.08, 3.4V, and 7.61 lm/W, respectively. The
commission International de I’Eclarirage(CIE) chromaticity coordinates obtained from the measured
spectra remained almost constant during the forward-baias current increase from 0.5 mA to 60 mA.
Wafer Level Bonding for LED Packaging Using Six Sigma Methodology
Authors: Park Ji Hyun , Lee Sung Jun , Choi Seog Moon
Published: March 2009

As Recently, wafer level packaging (WLP) received lots of attention in system because it
shows the potential to reduce packaging cost, while the yield of devices after dicing and packaging
can be increased. In this study, we newly proposed WLP for light emitted diodes (LED) using MEMS
technology. Our silicon package structure is composed of base and reflector cup. The role of base is
that settle LED chip at desired position and supply electrical interconnection for LED operation.
Reflector cup was formed by an-isotropic wet etching. Package platform could be fabricated by
eutectic bonding between base and reflector cup using AuSn. We carried out process using six sigma
methodology. We first decided 2 factors and 3 levels by design of experiment (DOE). One factor is
the kind of metal model. The other is the shape of pattern. It was used that three-kind metal models are
Au (cup), AuSn (cup), and AuSn (base). The bonding strength is measured using a die shear strength
tester. It carried out in the repetition experiment by a unit of 3 times. As a result of this test, the
AuSn(base) metal model and the No.3 pattern were applied by the optimal condition. We set the value
of the low limit at shear strength 950g/mm2 for applying sigma level. This value is a generally used for
eutectic bonding packages. The experiment results have 3.13 sigma level (95% yield). In this paper,
We show the final LED package which is finished up to LED attach, wire bonding, encapsulation, etc.
This wafer level bonding process demonstrates its promising potential at the wafer level packaging in
LED packaging.
Ceramic Coatings Deposited from Aqueous Solutions
Authors: Unuma Hidero
Published: March 2009

This paper reviews novel techniques developed in our laboratory to deposit ceramic
thin films from aqueous solutions. All the techniques are based on the heterogeneous nucleation
and growth phenomenon; ceramic precipitates are prone to be formed preferentially on
substrate/solution interfaces when the rate of the formation of the precipitates is appropriately
controlled. In “oxidative soak coating” method, metal ions with a lower valence state are
oxidized in homogeneous solutions to those with a higher valence state; thereby coatings of SnO2,
MnO2, CeO2, Co3O4 and Fe3O4 have been deposited. In “ligand decomposition” method, ligands
of an indium peroxo- complex are decomposed to promote spontaneous hydrolysis of the indium
ion; thereby In2O3 coating has been deposited. In “enzyme-assisted precipitation” method,
precipitant of metal ions is supplied by urease immobilized on a substrate to promote local
deposition of ceramics on the substrate, by which hydroxyapatite coating has been rapidly
deposited. The control of the rate of the precipitation reactions is the most important parameter.
Some properties of the resultant coatings are also presented.
Surface Characteristic of Ni-Based Amorphous Alloy Membrane for Hydrogen Permeation
Authors: Lee Dock Young , Kim Ha Young , Kim Ki Bae
Published: March 2009

The production of high purity hydrogen gas is an important technical issue for future energy
and environmental problem. The pure hydrogen is the ideal fuel in terms of fuel-cell performance.
There have been many investigations on the hydrogen permeation of Pd-coated membrane of
amorphous alloys. The purpose of this research is to characterize the surface such as roughness and
morphology of surface layer of Ni-based amorphous alloy membrane by atomic force microscopy
(AFM). The ribbon of Ni-Nb-Ta amorphous alloy was produced by a single-roller melt-spinning
technique. The surface characteristic of the amorphous alloy membrane was discussed in view of the
hydrogen permeation behavior. From the 3-dimensional AFM images, a lot of hole was observed on
the surface of the amorphous alloy membrane produced in air atmosphere. But, a lot of protrusion
were observed in the membrane produced in vacuum due to the selective growth on the high
oxygen-affinity element of the amorphous alloy. The average roughness of the membrane produced in
air atmosphere and vacuum was measured to be 0.359 and 0.263nm, respectively. Therefore, it was
considered that it would be suitable to produce the amorphous alloy membrane in vacuum.
Numerical Analysis of Self-Organizing Interconnection Process by 3 Dimensional Flow Dynamics
Authors: Ohta Koushi , Yasuda Kiyokazu , Matsushima Michiya , Fujimoto Kozo
Published: March 2009

The growing importance of high integration on electronics demands novel interconnection
methods replacing high-cost solder bumping or less reliable conductive adhesives. Self-organizing
interconnection process using resin containing solder fillers has a possibility to achieve high-density
joints satisfying both needs. Numerical study visualized the process and revealed that surface tension
of molten fillers and resin viscosity determine the speed of conductive path formation.
Synthesis of ZnO Flower-Like Nanostructures on GaN Epitaxial Layer by Hydrothermal Process
Authors: Jang Jae Min , Yi Sung Hak , Choi Seung Kyu , Kim Jeong A , Jung Woo Gwang
Published: March 2009

3D type flower-like ZnO nanostructure is fabricated on GaN epitaxial layer by
hydrothermal synthesis. The formation of ZnO nanostructures is controlled dominantly by pH of the
aqueous solution. The microstructure of flower-like ZnO nanostructure was examined by FE-SEM,
XRD and FE-TEM. It is found that the shape of ZnO nanostructures are likely flower and chestnut bur
shapes. FE-TEM and XRD analysis shows that ZnO nanostructures are single crystalline. Some
discussion is made on the mechanism of ZnO growth in solutions with different pH.
Fabrication of Antireflective Films Composed of High and Low Refractive Index Layers Using Layer-by-Layer Self-Assembly Method
Authors: Bae Jin Hye , Cho Jin Han , Char Kook Heon
Published: March 2009

We introduce a novel and versatile approach for controlling anti-reflective (AR)
properties of multilayer films based on layer-by-layer (LbL) self-assembly (SA) method. For the
fabrication of these films, blend (i.e., mixed) layers containing both polyanions (i.e., titanium
precursor (TALH) and poly(sodium 4-styrenesulfonate) (PSS)) were assembled with polycation (i.e.,
poly(diallyldimethylammonium chloride) (PDAD)) for the formation of the high refractive index
multilayers and on the other hand, the negatively charged silica particles with the diameter of about
100 nm were employed for low refractive index layer. The refractive index of TALH:PSS/PDAD
multilayer was controlled by blending ratio and annealing temperature as TALH has the relatively
high refractive index (n = 1.68) in comparison with that (n = 1.46) of conventional polyelectrolytes
(PEs) at room temperature and furthermore these titanium precursors are partially changed into
TiO2 with relatively high refractive indices (n = 1.50 ~ 1.81) at annealing temperature of 250 oC. In
the case of silica particle layer used for low refractive index layer, the calculated refractive index
was about 1.35 due to much vacancy among the adsorbed silica colloids although the inherent
refractive index of silica material is about 1.45. As a result, the films composed of
TALH:PSS/PDAD multilayers with tunable refractive index and silica colloidal layer can easily
modulate the optical properties of multilayer films by blending ratio and heat treatment.
Synthesis and Evaluation of Hollow-Tubular ZnO by Wet Chemical Method
Authors: Murase Hideaki , Shio Shoichiro , Nakahira Atsushi
Published: March 2009

In this study, morphology control of ZnO was performed by a wet chemical processing without
templates at room temperature. In special, the effect of aging time and pH of this wet processing on
ZnO morphologies was in detail investigated. As a result, products composed of a single phase of
ZnO with a unique morphology like a hollow tube were obtained. Then, it was found that an aging
process played an important role on controlling morphology of ZnO during this wet chemical
process. Furthermore, it was found that this hollow-tubular ZnO had a high transparency.
Synthesis of ZnO Nanostructures by Thermal Evaporation on Graphite
Authors: Lee Kon Bae , Cho Ki Seop , Lee Won Hee , Kwon Hoon
Published: March 2009

ZnO nanostructures have been synthesized on graphite substrates by thermal evaporation
of ZnO powder without a metal catalyst at a temperature of 1300. The colors of the as-synthesized
products gradually change from white and brown to gray as the distance from the source material
increases. ZnO particles were formed at higher temperature region. ZnO particles gradually changed
into ZnO nanowire as the temperature decreased. Finally, ZnO nanowires disappeared completely and
only Zn particles were observed at lower temperature region.
Fabrication and Micropatterning of Conducting Polymer Nano-Films for Electronic Displays
Authors: Kwon Min Hee , Han Dong Kyu , Kwon Si Joong , Kim Jin Yeol
Published: March 2009

We investigate the electrical conductive poly(3,4-ethylenedioxythiophene) (PEDOT)
nanofilms and micropatterning prepared by vapor-phase polymerization method using
self-assembling teacnique. The thin conductive films were uniformly fabricated between 20 and 100
nm, there surface resistance wasenhanced until to 102 /square, and the light-transmittance were also
increased as up to 95 %. We report a fabrication of electrically conducting PEDOT pattern on a
electrically insulating substrate using a microcontact printing method. Then, patterns are successfully
obtained with line widths down to 3 .
Synthesis and Nanophase-Separated Morphology of a Diblock Copolymer of Polypentafluorostyrene-b-Poly(methyl methacrylate) by Atom Transfer Radical Polymerization
Authors: Ko Yoon Soo , Kwon Yong Ku
Published: March 2009

We synthesized a symmetric, fluorine-containing diblock copolymer of
polypentafluorostyrene-b-poly(methyl methacrylate) (PPFS-b-PMMA) by atom transfer radical
polymerization (ATRP). The PPFS macroinitiator was also synthesized by ATRP by using
1-phenylethyl bromide initiator. The chemical structure of the polymer was confirmed by GPC,
1H-NMR and DSC measurements. Due to the chemical dissimilarity between the PPFS and PMMA
blocks, the microphase-separation was occurred during annealing at high temperature, displaying a
lamellar morphology with a thickness of approximately 35 nm.
Electrophoretic Self-Assembly of Sol-Gel Derived Silica Microspheres
Authors: Louh Rong Fuh , Huang Eric
Published: March 2009

Monosized silica microspheres (100−500 nm) were prepared by a sol-gel process by
using tetraethyl orthosilicate precursor. A well-dispersed suspension was obtained by adjusting
suspension to be weakly basic for a better yield of electrophoretic self-assembly (EPSA). A perfect
EPSA behavior of silica microspheres into the layered pattern with the FCC structure was created.
EPSA technique has been demonstrated as a simple and effective route to make numerous templates,
which are associated with 3-D structures of silica microspheres in asymmetric geometries, for design
of photonic crystals.
Initial Growth Mode of GaN Film on Stepped Sapphire
Authors: Yi Min Su , Cho Tae Sik , Lee Hyun Hwi
Published: March 2009

The initial GaN growth mode on stepped sapphires by plasma enhanced metal organic
molecular beam epitaxy (PEMOMBE) has been analyzed using in-situ, real time synchrotron x-ray
diffraction and x-ray absorption. The sapphire substrate annealed at high temperature had flat terraces
and regular atomic steps. The crystal quality and the vicinal angle of sapphire substrate had an effect
on the width of terraces and the step arrangement. The initial growth mode of the GaN film on the
regular atomic step (AS) surface was the layer-by-layer mode and changed to the 3D growth mode
within 2 bilayer thickness. In the meanwhile, the growth mode of the GaN film grown on the sapphire
with random roughness (RR) surface made the flat surface in the early stage and changed the 3D
growth mode. As increasing the film thickness, the nucleation layer grows strain-free hexagonal GaN
on stepped sapphires
Influence of Ion Bombardment of Sapphire on Electrical Property of GaN Layer
Authors: Choi Seung Kyu , Jang Jae Min , Jung Woo Gwang
Published: March 2009

Ion beam bombardment of proton, He+, Ar+, Xe+ ions were made on single crystal substrate
by cyclotron. The GaN epi-layer material was grown by MOCVD on ion beam bombarded substrate.
After deposition of GaN epi-layer heat treatment was made in flow of N2. The RMS roughness of the
substrate was increased by ion bombardment. The GaN crystal quality for substrates of ion
bombardment was better than that for bare substrates. Raman spectrum analysis indicated the induced
stress in the GaN epi-layer during the heat treatment. The electrical property of GaN was improved
after heat treatment. It is estimated that ion bombardment of proton with current of 1μA is the
optimum condition in our experimental condition.
Hydrogen-Sensor Prepared Using Proton-Conducting Glass Films
Authors: Matsumura Midori , Daiko Yusuke , Nogami Masayuki
Published: March 2009

Solid-state potentiometric thin film hydrogen gas sensors were successfully fabricated
using a sol-gel-derived high proton-conducting P2O5-SiO2 glass films. Manganese oxide thin film
coated on an indium tin oxide (ITO)-coated glass substrate was used for reference electrode. The
sensor exhibited high speed responsibility within 10 s and 120 s at 30 oC and -30oC, respectively, for
1 vol.% hydrogen gas. A linear relationship between the electromotive force (EMF) and the
logarithmic hydrogen concentration of 0.1~1 vol.% was obtained in the temperature ranging from
-30 to 30 oC. The sensing mechanism was also discussed to improve the sensitivity and sensing speed
against low H2 concentration at low temperatures.
Structural and Dielectric Properties of Screen Printed PZT(70/30) Multilayered Thick Films
Authors: Lee Sung Gap , Park Sang Man , Shim Young Jae , Rhee Young Chul
Published: March 2009

PZT(70/30) powder was prepared by a sol-gel method and PZT thick films were
fabricated by the screen-printing method on the alumina substrates. The coating and drying procedure
was repeated 4 times. And then the PZT(30/70) precusor solution was spin-coated on the PZT thick
films. A concentration of a coating solution was 0.5 mol/L and the number of coating was varied from
0 to 6.
The porosity decreased and the grain size increased with increasing the number of coatings. The
thickness of the PZT-6(6: number of coatings) films was about 60~65μm. All PZT thick films showed
the typical XRD patterns of a typical perovskite polycrystalline structure. The relative dielectric
constant of the PZT-6 thick film was 540. The remanent polarization and coercive field of the PZT-6
film were 23.6 μC /cm2, 12.0 kV/cm, respectively.
Synthesis of Silica Aerogel Thin Film from Waterglass
Authors: Cha Young Chul , Kim Chul Eui , Lee Seung Hun , Hwang Hae Jin , Moon Ji Woong , Han In Sub , Woo Sang Kuk
Published: March 2009

Hydrophobic thin film silica aerogels were synthesized by ambient pressure drying method
from silicic acid which was prepared from sodium silicate (water glass) solution. The pH value of the
silica precursor sol was adjusted to make a spinable sol, and gel films were coated on a glass substrate
by dip coating technique. Aerogel-like thin films with the thickness of about 1 μm could be
successfully fabricated by repeating the dip coating process three times.
Preparation of Filling Materials for Antifouling Mineral Paint Using Rare Earth and their Anion Emission Properties
Authors: Lee Jae Ryeong , Jeon Ho Seok , Lee Young Hyo , Chung Hun Saeng
Published: March 2009

Tourmaline has unique electrical properties originated from its crystal structure such as
pyroelectricity, piezioelectricity and emission of anion. These properties can derivate the making of
feeble current around 0.06 mA. This weak current enables to electrolyze continuously and to make the
hydroxyl anion, which may play a role of surface active agent against fouling of ocean organism. Two
kinds of the mixture, tourmaline-monazite-quartz and tourmaline-monazite-illite-zeolite, were tested
for the filling materials of antifouling paints. As a whole, the anion emits actively, at least around
4000 negative ion/cc. This high emission property maintains constantly for long time over 500 days.
This implies that the tourmaline mixture treated mechanochemically can emit anion over 4000
negative ion/cc for a long time. These results enable us to make possible for application of the
tourmaline containing mixture as the filling materials of antifouling paint
Strength and Surface Morphology of Si3N4 Composite Ceramics Coated with SiO2 Gel
Authors: Kim M.K. , Kim H.S. , Kang S.B. , Ahn S.H. , Nam Ki Woo
Published: March 2009

The Si3N4/SiC and Si3N4/SiC/TiO2 composite ceramics were sintered at 1850 °C, for 2 h, in
air by Hot-Press. A semi-elliptical surface crack was made at the center of the tensile surface of the
test specimen using a Vickers indenter at a load of 24.5 N. By this method, the crack length on surface
was made the semi-elliptical cracks of about 100 ㎛. Crack-healing behavior depends on healing
temperature. The optimum healing condition of Si3N4/SiC and Si3N4/SiC/TiO2 composite ceramics
are well known for 1,300 °C, 1h in air environment. So Smooth and as-cracked specimens were
heated in this condition. To investigate temperature-dependence of the SiO2 gel coated specimen,
four kinds of temperatures (800, 900, 1000, 1,300 °C) were tested. And to investigate SiO2 gel coating
time-dependent, one and three times were coated. SiO2 gel coated specimens indicated increase of
bending strength as the temperature goes up. Moreover the bending strength of SiO2 gel coating
specimens was similar to the bending strength of healed smooth specimen at 900 °C.
Fabrication of Flexible CIGS Solar Cell on Stainless Steel Substrate by co-Evaporation Process
Authors: Kim Min Sik , Yun Jae Ho , Yoon Kyung Hoon , Ahn Byung Tae
Published: March 2009

Silicone dioxide (SiO2) layer as an electrical insulator and diffusion barrier was deposited
on a flexible stainless steel substrate by plasma enhanced CVD process. And we deposited
Mo/Na-doped Mo bi-layer back contact on the oxide layer in order to supply Na into the CIGS
absorber. Then we deposited CIGS layer by three-stage process using elemental co-evaporation
method and completed the solar cell fabrication. Without antireflection coating, the best CIGS solar
cell on the stainless steel showed the conversion efficiency of 10.57 % with Jsc = 33.38 mA/cm2 and
Voc = 0.519 V and FF = 0.61 for an active area of 0.45 cm2.
Low Temperature Sintering in 95(Na0.5K0.5)NbO3-5LiTaO3 Ceramics
Authors: Kim Min Soo , Oh Seok , Lee Dae Su , Park Eon Cheol , Jeong Soon Jong , Kim In Sung , Song Jae Sung , Oh Young Woo
Published: March 2009

Na2O excess 95(Na0.5K0.5)NbO3-5LiTaO3 (NKN-5LT) ceramics were developed by
conventional sintering process. Sintering temperature was lowered by adding Na2O as a sintering aid.
Grain growth behaviors with Na2O addition were explained in terms of the effect of Na2O on interface
reaction - controlled grain growth and the critical driving force. The electrical properties of NKN-5LT
ceramics were investigated as a function of Na2O concentration. In the 1 mol% Na2O excess
NKN-5LT samples sintered at 1000oC for 4h in air, electromechanical coupling factor (kP) and
piezoelectric coefficient (d33) of NKN-5LT ceramics were found to reach the highest values of 0.43
and 190 pC/N, respectively.