bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Current Type and Density on Dishing Phenomena in CMP Process
Authors: Cho Woong , Ko Yong Jun , Ahn Yoo Min , Chang Gun Ho , Lee Jae Ho
Published: March 2009

The dishing phenomena of soft materials in chemical mechanical polishing (CMP) process
were problematic in delineating inlaid metal patterns. The inlaid copper structures were fabricated on
Si wafer where SiO2 was thermally grown. Seed layer was deposited by thermal evaporate method
followed by copper electrodeposition. Copper was electrodeposited with IBM paddle type
electroplating machine to obtain uniform thickness of coating. The dishing amounts were measured
at various current density and current type. The dishing amounts with pattern density and line width
were also measured. The losses of copper were not sensitively dependent on current density however
those were dependent on current type. The dishing amount of copper was decreased at high pattern
density especially over 50% and increased with line width. Surface topology and grain size of coating
were investigated with surface profilometer and FESEM.
Development of Conductive Ceramic Composites by Preceramic Polymer
Authors: Kim Beom Seob , Kim Deug Joong
Published: March 2009

The formation, microstructure and electrical property of conductive ceramic composites
derived from polymer pyrolysis were investigated. Methylpolysiloxane was mixed with TiH2 as a
filler and pyrolyzed in nitrogen, argon and vacuum atmosphere at a temperature of 1600oC for 1
hour after the preheat treatment at 850oC in N2 atmosphere. Depending on the atmosphere
conditions, TiN and Ti5Si3 phases were formed by reaction of TiH2 as reactive filler and
atmospheric gas or pyrolytic product such as SiO2. Consequently, the microstructures of the ceramic
composites with 70 vol.%TiH2 pyrolyzed at 1600oC for 1 hour in vacuum were composed of TiN
and Ti5Si3 particles. The density and electrical conductivity of the ceramic composites were 97.3
TD% and 6200 ohm-1⋅cm-1, respectively. These composites pyrolyzed by polymer were considered
as superior conductive material with a value of 103 ~ 104 in log scale at room temperature.
Properties of Electrical Conductivity of Amorphous Tungsten-Doped Vanadium Oxide for Uncooled Microbolometers
Authors: Han Yong Hee , Lee Seung Hoon , Kim Kun Tae , Choi In Hoon , Moon Sung
Published: March 2009

In recent years, we have reported uncooled microbolometer with amorphous
vanadium-tungsten oxide as a thermometric material. The reported tungsten-doped vanadium oxide
showed very high TCR over -3.0%/K compared with common vanadium oxide, which generally has
the TCR values near -2.0%/K. In this work, we characterized properties of electrical conductivity of
amorphous tungsten-doped vanadium oxide by investigating electronic structure between vanadium
oxide and tungsten-doped vanadium oxide. Finally, it is concluded that tungsten addition into
vanadium give rise to changes of electronic structure when pure vanadium is oxidized and this
changes of electronic structure attribute to electrical properties such as high TCR values of
vanadium-tungsten oxide.
Effect of Hydrogen on Electron Emission Characteristics of MgO for Plasma Display Panel
Authors: Park Kyung Hyun , Ko Min Soo , Kim Yong Seog
Published: March 2009

Characteristics of MgO layer deposited under hydrogen atmosphere were investigated.
Hydrogen gas was introduced during e-beam evaporation coating process of MgO layer and its effects
on microstructure, cathode luminescence spectra, discharge voltages and effective yield of secondary
electron emission were examined. The results indicated that the hydrogen influences the
concentration and energy levels of defects in MgO layer and that affects the luminance efficiency and
discharge delays of the panels significantly.
Dispersion of Glass Powder and Characterization of Thick Film for AC Plasma Display Panels
Authors: Park Kwan Wuk , Lee Jin Seok , Lim Hee Jin , Choi Sung Churl
Published: March 2009

Bi-based glass pastes were prepared in the mixed organic solvents (α-terpineol and texanol)
with different kinds and concentrations of organic dispersant such as fish oil , phosphate ester and
poly methyl methacrylate (PMMA). The rheological stability of glass pastes was characterized by
using a rheometer and adsorption behavior of organic additives for the glass powders was carried out
by using a thermal gravimetric analyzer (TGA).The Bi-based glass pastes exhibited the most stable
rheological behavior at an addition of phosphate ester of 0.5 in mass %, due to the steric repulsive
force acting on the surface of glass powers with adsorbing the organic additives. This study allowed
significant delay of the sedimentation time and suppressed generation of micropores during practical
forming process by a screen printing method.
Thermal Stress Model for Phase Change Random Access Memory
Authors: Kim Sung Soon , Bae Jun Hyun , Do Woo Hyuck , Lee Kyun Ho , Kim Young Tae , Park Young Kwan , Kong Jeong Taek , Lee Hong Lim
Published: March 2009

Thermal stress model considering the effect of phase transformation is proposed for
Phase-Change Random Access Memory (PRAM). The results of simulation show that the high level
of stress is generated on the junction where Ge2Sb2Te5(GST), TiN and SiO2 meet together. The high
level of stress can also be observed in the interface between TiN and SiO2. From simulation results, it
can be predictable that delamination between GST and TiN can occur during operation of PRAM. It is
expected that the simulation model, which has been developed in this research, is very useful tool for
PRAM device design.
Aligned Polycrystalline Silicon Array Thin Film by XeCl Excimer Laser Annealing for AMOLED Displays
Authors: Chen C.N. , Wu G.M. , Feng W.S.
Published: March 2009

Low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) are demanded
to fabricate high performance liquid crystal displays (LCD) and organic light-emitting diode displays
(OLED). The mobility of poly-Si TFT can be two orders of magnitude higher than that of amorphous
Si (a-Si) TFT. Excimer laser annealing has been studied to be the most promising technology to meet
the stringent requirement in high speed operation. The process parameters were identified as a-Si
thickness, laser energy density, overlap ratio, annealing atmosphere and pre-clean condition. The a-Si
layer of 40-50 nm was deposited by plasma enhanced chemical vapor deposition (PECVD). The XeCl
excimer laser was irradiated on the a-Si film at room temperature under N2 or N2/O2 environment.
The energy density ranged 250-400 mJ/cm2, and the overlap ratio was 95-99%. The highly aligned
poly-Si array thin film could be obtained. The grain size has been about 0.31x0.33 μm2, and the
regular arrangement in poly-Si grains was discussed. In addition, the PMOS TFT has been fabricated
from the aligned poly-Si array. The mobility was as high as 100 cm2/Vs and the sub-threshold swing
was around 0.24 V/dec. The threshold voltage was -1.25 V and the on/off current ratio was about 106.
Enhanced Luminescence Efficiency for Bi, Eu Doped Y2O3 Red Phosphors for White LEDs
Authors: Park W.J. , Jung M.K. , Yoon Dae Ho
Published: March 2009

Bi and Eu co-doped Y2O3 was used as a red phosphor with a very high efficiency
synthesized by the solid state reaction and co-precipitation The emission spectrum consisted of a weak
band at 581, 587, 593 and 599 nm corresponding to the 5D0 → 7F1 transition, with sharp peaks of maximum
intensity occurring at about 611 nm due to the 5D0 → 7F2 transition of Eu3+. In addition, the excitation
spectrum exhibited a broad band between 250 and 550 nm with peaks occurring at about 310 – 400
nm and a sharp peak at 465.5 nm. The relative emission intensity was improved by co-precipitation
synthesis as compared to solid state reaction synthesis. This implies that an appropriate
co-precipitation synthesis could improve the luminescent efficiency, particularly for the samples
prepared with the optimized firing temperature of 1100 °C.
Characteristics of Amorphous Indium Zinc Oxide Anode Films on Polycarbonate Substrate for Flexible Organic Light Emitting Diode
Authors: Kim Han Ki , Bae Jung Hyeok , Moon Jong Min , Kim Sang Woo , Jeong Soon Wook , Kim Do Geun , Kang Jae Wook
Published: March 2009

Electrical, optical, and structural properties of amorphous indium zinc oxide (IZO) anode
films grown on flexible polycarbonate (PC) substrate were investigated. The x-ray diffraction (XRD)
result shows that the IZO film grown at room temperature is complete amorphous structure due to low
substrate temperature. A sheet resistance of 34.1 ,/, average transmittance above 88.9% in visible
range, and root mean spare roughness of 3.5~10.5 Å were obtained even in the amorphous IZO anode
film grown on PC substrate at room temperature. It is shown that the Ir(ppy)3 doped-flexible organic
light emitting diode (OLED) fabricated on the amorphous IZO anode exhibit comparable
current-voltage-luminance characteristics as well as external quantum efficiency and power
efficiency to OLED fabricated on conventional ITO/glass substrate. These findings indicate that the
IZO anode film is a promising anode material for the fabrication of flexible OLEDs.
Optical and Electrical Properties of ITO/Ag/ITO Multilayer Thin Films Deposited by D.C. Magnetron Sputtering
Authors: Choi Yong Lak , Kim Seon Hwa
Published: March 2009

ITO monolayer and ITO/Ag/ITO multilayer thin films are prepared by D.C. magnetron
sputtering method, optical and electrical properties were estimated with different crystalline
properties and microstructures. The coated Ag layer thickness was around 50 , and the surface of
ITO/Ag/ITO thin film had the very fine island morphology. The growth of columnar phase was
inhibited, and most of phases were amorphous. The carrier concentration increased above 10 times
because of the effect of Ag layer, and the observed sheet resistance gave much lower value of below
4 / compared to that of coated crystalline ITO thin film that was 10 / , and the transmittance
was 80%.
Instability of OTFT with Organic Gate Dielectrics
Authors: Lim Sang Chul , Kim Seong Hyun , Kim Gi Heon , Koo Jae Bon , Lee Jung Hun , Ku Chan Hoe , Yang Yong Suk , Kim Do Jin , Zyung Tae Hyoung
Published: March 2009

We report the effects of instability with gate dielectrics of pentacene thin film transistors
(OTFTs) inverter circuits. We used to the UV sensitive curable resin and poly-4-vinylphenol(PVP) by
gate dielectrics. The inverter supply bias is VDD= -40 V. For a given dielectric thickness and applied
voltage, pentacene OTFTs with inverter circuits measurements field effect mobility, on-off current
ratio, Vth. The field effect mobility 0.03~0.07 cm2/Vs, and the threshold voltage is -3.3 V ~ -8.8 V.
The on- and off-state currents ratio is about 103~106. From the OTFT device and inverter circuit
measurement, we observed hysteresis behavior was caused by interface states of between the gate
insulator and the pentacene semiconductor layer.
Improvement of Surface Morphologies of Ru Thin Films by 2-Step MOCVD Process Using (2,4-Demethylpentadienyl)(Ethylcyclopentadienyl)Ruthenium and Oxygen
Authors: Kim Beom Seok , Hwang Cheol Seong , Kim Hyeong Joon
Published: March 2009

Ru thin films were grown by metalorganic chemical vapor deposition (MOCVD) on TiN
and TEOS oxide substrates at 300oC using (2,4-demethylpentadienyl)(ethylcyclopenadienyl)
ruthenium [Ru(DMPD)(EtCp)] and oxygen. Instead of conventional single step process, we
investigated 2-step CVD process to enhance initial nucleation rate and reduce the incubation time for
film formation. This process consisted of a seeding step, where high flow rate of oxygen and low
process pressure were used, and a film growth step with low O2 flow rate and high pressure. The
deposited Ru films by 2-step process have smooth surface morphologies compared to those by single
step process.
Failure Mechanism of Patterned ITO Electrodes on Flexible Substrate under Static and Dynamic Mechanical Stresses
Authors: Oh Jeong Seob , Cho Young Rae , Cheon Ko Eun , Karim Md.A. , Jung Seung Jin
Published: March 2009

The mechanism of failure of patterned ITO electrodes on PET was investigated under static
and cyclic bending in the mechanical stress mode. When mechanical stresses are increased, two types
of micro-cracks are observed depending on the stress modes. The direction of the micro-crack in ITO
electrodes is perpendicular to the load for the static mode. The electrical resistance of an ITO
electrode is related to the density of the micro-cracks and failure mechanism of ITO electrode.
Microstructure and Electrical Properties of ITO Films Deposited Using Various ITO Targets by Magnetron Sputtering
Authors: Park Joon Hong , Lee Sang Chul , Lee Jin Ho , Song Pung Keun
Published: March 2009

Indium Tin Oxide (ITO) films were deposited on non-alkali glass substrate by magnetron
sputtering using commercial ITO target (target A) and improved ITO target (target B). Depositions
were carried out at total gas pressure (Ptot) of 0.5 Pa, substrate temperature (Ts) of RT ~ 300 °C,
oxygen flow ratio [O2/(O2+Ar)] of 0 ~ 1.0% and dc power of 100W. Target B showed relatively
higher stability in film resistivity with increasing sputtering time, i.e., erosion ratio of target surface.
Optimum oxygen ratio to obtain the lowest resistivity was decreased with increasing substrate
temperature. The lowest resistivity was 1.06x10-4 6cm for the film deposited using target B at
O2/(O2+Ar) ratio of 0.05% and at Ts =300 °C.
Characteristics of Pentacene with Different Polymer Gate Insulators for Organic Thin-Film Transistors
Authors: Kim Jung Min , Her Hyun Jung , Yoon J.H. , Kim Jae Wan , Choi Y.J. , Kang C.J. , Jeon D. , Kim Yong Sang
Published: March 2009

We investigated the characteristics of pentacene thin films of different materials for gate
insulators using atomic force microscope (AFM) and x-ray diffraction (XRD). The pentacene thin
films are fabricated by evaporation on different polymer substrates. We used HMDS (Hexa Methyl
Di Silazane), PVA (Poly Vinyl Alcohol) and PMMA (Poly Methyl Meth Acrylate) for the polymer
substrates, on which pentacene is deposited at various substrate temperatures. The case of pentacene
deposited on the PMMA has the largest grain size and least trap concentration. We also fabricated
pentacene TFTs with the PMMA gate insulator. Pentacene TFTs with PMMA gate insulator, shows
high field-effect mobility (ｕFET= 0.03 cm2/Vs) and large on/off current ratio (>105) and small
threshold voltage (Vth= -6 V).
Comparison of Natural Type Ia Diamond and CVD Diamond Films by Photoluminescence
Authors: Seo Jin Kyo , Lee Jeong Hwan , Park Jong Wan
Published: March 2009

The crystal defects in diamonds are diverse. In other words, there are almost no perfect
diamonds without impurities or dislocations. Most natural diamonds contain a considerable amount
of nitrogen impurity in aggregated forms. CVD diamond films also included many crystal defects.
We investigated the distribution of luminescence center of natural type Ia diamonds and CVD
diamond films by various photoluminescence excitation source. Photoluminescence (PL)
spectroscopy is a useful technique to provide information on defects of diamond with high sensitivity.
Effects of Electroplating Parameters on the Defects of Copper via for 3D SiP
Authors: Cho Byeong Hoon , Lee Won Jong , Lee Jae Ho
Published: March 2009

Electroplating of copper in via filling is very important in 3D SiP (System in Packaging).
Defect free via filling can be obtained through additive in the electrolyte and current type control. Via
in Si wafer were formed by RIE method with 170 &m depth and 50 &m in diameter. Seed layers were
deposited by ionized metal plasma (IMP) sputtering; Ta for diffusion barrier, Cu for conductive layer.
Via was filled with copper by electroplating method. Different types of additives were used in via
filling; PEG, SPS, Cl- and JGB. Defects in via were controlled and eliminated by precise monitoring
of additive concentration and input current. The optimum condition of electroplating was determined
by getting cross-sectional images of filled vias and by determining the degree of via filling.
Reliability of Electroplated Sn-37Pb Solder Bumps with Different Under Bump Metallizations (UBMs) during High Temperature Storage Test
Authors: Koo Ja Myeong , Kim Dea Gon , Jung Seung Boo
Published: March 2009

The interfacial reactions and shear properties of Sn-37Pb (wt.%) solder bumps with two
different under bump metallizations (UBMs), Cu and Ni, were investigated after high temperature
storage (HTS) tests at 150 C for up to 65 days. Two different intermetallic compounds (IMCs),
Cu6Sn5 and Cu3Sn, were formed at the bump/Cu interface, whereas only a Ni3Sn4 IMC layer was
formed at the bump/Ni interface. The thicknesses of these IMCs increased linearly with the square
root of duration time. The IMC growth rate at the bump/Cu UBM interface was much greater than that
at the bump/Ni UBM interface. The shear properties of the bumps with the Cu UBM were greatly
decreased with increasing duration time, compared with those with the Ni UBM.
Comparison of Amorphous Selenium and Mercuric Iodide Film for Diagnostic X-Ray Imaging
Authors: Park Ji Koon , Kang Sang Sik , Cho Sung Ho , Kim So Yeong , Son Dae Woong , Shin Jung Woog , Choi Jang Yong , Chun Byung Kyu , Nam Sang Hee
Published: March 2009

In this paper, we present the imaging parameters and compare both mercuric iodide (HgI2)
and amorphous selenium (a-Se) films. Using MCNPX code, we designed the film structure and its
thickness for the optimized detector in the diagnostic x-ray range. The mercuric iodide film was
formed by a wet binder process, while the amorphous selenium film was deposited by physical vapor
deposition (PVD). These deposition methods are capable of being scaled up to sizes required in
diagnostic imaging applications. The electronic properties are investigated using dark current, x-ray
sensitivity and signal to noise ratio (SNR). From our results, the developed HgI2 film as an alternative
to a-Se photoconductor, which is in practical use in flat panel x-ray imaging detector, will prove its
usefulness in the future design and the optimization for various diagnostic modalities.
Growth Mode Diagram for the Epitaxial Growth on the Vicinal Surface of Strained Si (001)
Authors: Cha Pil Ryung
Published: March 2009

We present the linear stability analysis for the epitaxial thin film growth on the vicinal
surface of strained Si and the growth mode diagrams of the epitaxial growth under various operation
conditions. Competition between step-step elastic interactions and the asymmetry of incorporation of
adatoms from the terraces to step edge is considered. Force monopoles at steps and their interaction
lead to it on the vicinal surface while kinetic asymmetry of the adatom incorporation at steps due to
Ehrlich-Schwoebel barrier prevents the step bunching instability. Growth mode on the vicinal surface
is determined by the competition between elastic step-step interactions and Ehrlich-Schwoebel
barrier.
Synthesis and Characterization of TMA-A Zeolite Nanocrystals
Authors: Kim Young Mi , Lee Seok Ju , Kim Ik Jin
Published: March 2009

Well-controlled cubic nanocrystal of TMA-A zeolite with a size of 60~100 nm were
synthesized by a hydrothermal method in a solution having a Al(i-pro)3 : 2.2 TEOS : 2.4 TMAOH:
0.3 NaOH : 200H2O composition. The single TMA-A nanocrystals has an average lattice constant
of 24.61 Å having a surface area of 742.36 m2/g. Thermal treatment of TMA zeolite crystals results
in the formation of an amorphous above 900oC. Environmental scanning electron microscopy
(ESEM). high resolution transmission electron microscopy(HRTEM), X-ray powder
diffraction(XRD), fourier transform infrared(FT-IR) spectroscopy, DTA/TGA and BET analysis
were used to characterize the initial materials and the obtained products after various heat
treatments.
Influence of Structural Parameters to Engineer the Band Gaps in Ternary Pnictide Semiconductors - Theory as a Tool
Authors: John Rita
Published: March 2009

The band gap anomaly exhibited by ABC2 : A = Cd; B = Si,Ge,Sn; C = P,As pnictides
with respect to their binary analogs GaP, Ga0.5In0.5P, InP, GaAs, Ga0.5In0.5As, InAs is studied using
Tight Binding Linear Muffin Tin Orbital (TBLMTO) method as an investigating theoretical tool.
The influence of the structural parameters, η and u are analyzed to enable one to tune energy gap to
make tailor made compounds.
Self-Assembled Nanostructures of Block Copolymers on Random Copolymer Brush
Authors: Kim Bong Hoon , Koo Chong Min , Jeong Seong Jun , Shin Dong Ok , Kim Sang Ouk
Published: March 2009

We synthesized the polymer brushes by conventional free radical polymerization and
investigated the morphology evolution of block copolymer nanostructure on the brush treated
surfaces. Our simple approach utilized a functionalized free radical initiator to add hydroxyl group
to a chain end and an excess amount of a chain transfer agent to control the molecular weights of
the brushes. The synthesized polymer brushes had narrow molecular weight distribution as well as
hydroxyl end group and were successfully grafted onto silicon oxide layer by simple spin-coating
and annealing process. The orientation of poly(styrene-block-methyl methacrylate)s (PS-b-
PMMAs) coated on the brush grafted surface was finely controlled by the surface modification by
polymer brushes.
Resistive Switching Characteristics in TiO2 ReRAM with Top Electrode of Co Selectively Formed on SAMs Printed Patterns
Authors: Won Sang Hee , Go Seung Hee , Lee Jae Gab
Published: March 2009

Simple process for the fabrication of Co/TiO2/Pt resistive random access memory,
called ReRAM, has been developed by selective deposition of Co on micro-contact printed (μ-CP)
self assembled monolayers (SAMs) patterns. Atomic Layer Deposition (ALD) was used to deposit
TiO2 thin films, showing its ability of precise control over the thickness of TiO2, which is crucial to
obtain proper resistive switching properties of TiO2 ReRAM. The fabrication process for Co/TiO2/Pt
ReRAM involves the ALD of TiO2 on sputter-deposited Pt bottom electrode, followed by μ-CP with
SAMs and then selective deposition of Co. This results in the Co/TiO2/Pt structure ReRAM. For
comparison, Pt/TiO2/Pt ReRAM was produced and revealing the similar switching characteristics as
that of Co/TiO2/Pt, thus indicating the feasibility of Co replacement with Pt top electrode. The ratios
between the high-resistance state (Off state) and the low-resistance state (On state) were larger than
102. Consequently, the selective deposition of Co with μ-CP, newly developed in this study, can
simplify the process and thus implemented into the fabrication of ReRAM.
Effects of Paraffin Addition on Optical Properties and Self-Assembly of SiO2 Photonic Crystal
Authors: O Yong Taeg , Shin Dong Chan
Published: March 2009

The effects of paraffin addition on the optical properties and crystallinity of selfassembled
SiO2 photonic crystal (PC) were examined using a silica nanopowder. The silica
nanopowder was fabricated using the well-known Stöber process. During the evaporation process
for self-assembly of PC, the nanopowder content was 0.05 or 0.2 wt%, the paraffin addition was
fixed to 0.001 wt%, the process temperature was 80oC and the heat-treatment temperature after
evaporation was 900oC. The addition of paraffin reduced the defects in the PC layer, thereby
resulting in good crystallinity and transmittance. Our results suggested that paraffin can enhance the
bonding force between silica nanopowders.
Al-Substituted Li[Li(1/3-x/3)Crx-0.05M0.05Mn(2/3-2x/3)]O2 Cathode Synthesized via Sol-Gel Process
Authors: Mangani I. Ruth , Park C.W. , Yoon Y.K. , Kim S.H. , Kim J.
Published: March 2009

This work reports the effect of doping aluminium in the Li[Li(1/3-x/3)Crx-0.05M0.05Mn(2/3-
2x/3)]O2 (x= 0.2; M= Al), layered cathode material. The cathode material was prepared by citric acid
assisted sol-gel process. The sample is characterized by TG/DTA, XRD and FESEM measurements.
The Al- doped cathode has delivered an initial discharge capacity of 250 mAh/g with a current
density of 0.12 mA/cm2.
Direct Formation of Zn-Al Layered Double Hydroxide Thin Films Intercalated with Various Organic Anions through the Sol-Gel Method with Hot Water Treatment
Authors: Yamaguchi Naoko , Tadanaga Kiyoharu , Tatsumisago Masahiro
Published: March 2009

Zn-Al layered double hydroxide (LDH) thin films intercalated with various organic
anions were prepared by immersion of sol-gel derived amorphous Al2O3-ZnO thin films in hot
water containing organic salts like sodium dodecyl sulfate (SDS), sodium p-toluenesulfonate, and
benzenecarboxylates. In all the systems, extended interlayer spacing of the Zn-Al LDH was
observed after immersion in distilled water with the organic salts in comparison to the LDH with
carbonate anions, indicating that we have succeeded in direct formation of Zn-Al LDH films with
various organic anions on the substrates. It is suggested that divalent anions such as terephthalate
ion have higher selectivity than monovalent anions.
Fabrication of Pb-Free Silver Paste and Thick Film Adding Silver Nanoparticles
Authors: Park Sung Hyun , Seo Dong Seok , Lee Jong Kook
Published: March 2009

Fabrication of paste at low temperature has been developed in order to apply for various
electronic devices, such as bus electrode and address electrode in PDP, especially for enlargement of
a screen size. In this study, nano-sized silver particles with 10 - 30 nm were synthesized from silver
nitrate (AgNO3) by a chemical reduction method. To prepare Pb-free silver paste, the silver
nanoparticles were mixed with conventional silver powder with an average particle size of 1.6 and
conventional Pb-free frit. Thick films were fabricated from silver paste by a screen printing on
alumina substrate and the films were fried at temperatures ranging from 550 °C to 600 °C.
Microstructures of the fried thick films were analyzed by FE-SEM. Sheet resistivity of fried thick
films was measured and also the relationship between sinterability and conductivity of these films
were investigated.
Etching Mechanism of ZnO Thin Films in Inductively Coupled Plasma
Authors: Kang Chan Min , Kim Jong Sik , Kim Gwan Ha , Kim Chang Il
Published: March 2009

The etching properties of the ZnO thin films in the inductively coupled Cl2/Ar plasma
(ICP) were studied in the terms of etch rate and selectivity as functions of gas mixing ratio, ICP coil
power and dc bias voltage. The maximum etch rate of 129.3 nm/min was obtained for the mixture of
20% Ar/80% Cl2. The X-ray photoelectron spectroscopy (XPS) analyses of the ZnO surfaces etched at
various Cl2/(Cl2+Ar) mixing ratios revealed the formation of the ZnClx and ClOx reaction by-products
as a result of the increased etch rate with increasing Cl2 addition, compared with 100% Ar+ sputter
etching. From the analysis of these data, it was proposed that the maximum on the etch rate may be
explained by the concurrence of chemical and physical pathways in the ion assisted chemical reaction.
Inorganic Aerogel Granules Dried at Atmospheric-Pressure
Authors: Yeo Jeong Gu , Hong Jeong Min , Cho Churl Hee , Bhagat Sharad D. , Kim Yong Ha , Ahn Young Soo
Published: March 2009

Silica aerogels using sodium silicates was synthesized by atmospheric-pressure drying.
Granulation of silica aerogels was carried out in sequence of hydrogel formation, aging, surface
modification, and drying. Rapidly prepared aerogels showed good properties in case aging and
surface modification was done within 1 day. Drying is critical to aerogel granulation and the BET area
of aerogel dried for a short duration had decreasing with time. It is suggested that sodium
silicate-based aerogels granulation could be prepared within less than 5 days, half of initial processing.
Aerogel granules had the average diameter of 1 mm and nearly spherical shape. It has very low
thermal conductivity of 0.010 W/m⋅K, very light-weight and nanoporous structure with a porosity of
upto 95%.
Gas Permeation Properties of Poly(N-Vinylpyrrolidone)/ 3-Aminopropyltriethoxysilane Hybrid Membranes
Authors: Jang Kyoung Mi , Kim Jun Seok , Lee Sung Koo , Kim Hyun Joon
Published: March 2009

The organic-inorganic hybrid membranes of poly(N-vinylpyrrolidone) (PVP) and 3-
aminopropyltriethoxysilane (APTEOS) were prepared by sol-gel process and their permeation
properties of N2 and O2 were studied. The gas permeability coefficients of N2 and O2 are increased
with increasing temperature in a range of 30-50°C. The positive dependence on temperature and
higher ideal separation factor than theoretical Knudsen value indicates that PVP/APTEOS hybrid
membranes follow solution-diffusion mechanism, which is applied to nonporous membrane. The
permeability coefficients of N2 and O2 are decreased with increasing PVP content, at a given
temperature. It can be explained that the stronger interaction between PVP and APTEOS reduces
available free volume, although the increasing of PVP content may lead to an enhancement of chain
flexibility.
Formation of Spherical and Rod-Shaped TiO2 Nanocrystals Prepared by Reverse Micelle Method
Authors: Kim Eun Yi , Yoon Mi Young , Kim Yoo Hang , Whang Chin Myung
Published: March 2009

Uniform spherical- and rod-shaped TiO2 nanoparticles of anatase phase were prepared
using decanoic acid at 300°C by reverse micelle method. The nanoparticles were characterized by
transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffractometry
(XRD) and FT-Raman spectroscope. The content of decanoic acid and operating temperature were
noted as crucial parameters, controlling the shape, size and phase of TiO2 nanoparticles. RMS
roughness (1.62 nm), measured by atomic force microscope (AFM), confirmed its superiority over
other methods. The DCB photodegradation reaction rate constant (first order) TiO2 nanoparticles was
found superior to that of commercial TiO2, Degussa P-25.
Mechanical Properties and Fabrication of Silicon Carbide Ceramic by NITE Method
Authors: Yoon Han Ki , Lee Young Ju , Park Yi Hyun , Park Joon Soo , Kohyama Akira
Published: March 2009

Nano infiltration transient eutectic ceramic (NITE-SiC) was fabricated by hot pressing
method using Al2O3 and Y2O3 as sintering additives. The ratio of the Al2O3/Y2O3 additives was
changed between 6:4 and 4:6. The densification and mechanical properties were investigated for the
sintered temperature. The starting powder was high purity β -SiC nano-powder with an average
particle size of 30nm. The bending strength characterization and densification of NITE-SiC was
investigated by the FE-SEM and three point bending test.
Densification Behavior and Microstructure Evolution of SiCf/SiC Composites Incorporated with In Situ Grown SiC Nanowires
Authors: Kang Seok Min , Kim Weon Ju , Park Ji Yeon , Yoon Soon Gil , Ryu Woo Seog
Published: March 2009

SiC nanowires could be grown homogeneously within SiC fiber preforms by controlling
the concentration of a reactant gas. The morphology and the growth behavior of the SiC nanowires
were largely dependent on the degree of the reactant supersaturation. The SiC nanowires
incorporated in the fiber preform increased the surface area at which the matrix deposition could
take place, enhancing an efficiency of the matrix infiltration and altering the remaining pore
structure of the SiCf/SiC composite.
Sintering and Oxygen Ionic Conducting Properties of Bi2V0.9Co0.1O5.5-δ Derived from an EDTA-Citrate Precursor
Authors: Zhang Feng , Xu Qing , Huang Duan Ping , Chen Wen , Liu Han Xing , Zhou Jian
Published: March 2009

Bi2V0.9Co0.1O5.5-δ with a pure Aurivillius phase was synthesized by a sol-gel method using
EDTA and citric as mixed complexing agents. It was found that homogeneous and fine powder
(100-200 nm) with a pure Aurivillius phase can be produced by calcining the complex precursor at
450 °C for 1h in air. The sintering properties of Bi2V0.9Co0.1O5.5-δ were investigated in the range of
560-680 °C with respect to relativity density. Sintering at 640 °C was ascertained to be preferred for
Bi2V0.9Co0.1O5.5-δ, producing a dense microstructure with uniform grains around 3-5 μm. The
Bi2V0.9Co0.1O5.5-δ ceramic exhibits an oxygen ionic conductivity of 1.0×10-1 S·cm-1 at 600 °C. The
difference between the activation energies for the ionic conducting in low and high temperature
regions is qualitatively interpreted in terms of an order-disorder phase transition. This research
demonstrates the advantage of the EDTA-citrate method in preparing Bi2V0.9Co0.1O5.5-δ with respect
to the simplicity of synthesis process, desired morphology of synthesized powder, low sintering
temperature and superior ionic conducting properties of ceramic specimen.
Effect of Current Ratio on Plasma Electrolytic Oxide Coatings on Mg-Al Alloy
Authors: Chang Si Young , Kim Ye Lim , Song Byung Heum , Lee Jae Ho
Published: March 2009

Ceramic coatings were synthesized on pure Mg and binary Mg-7.1wt%Al alloy by plasma
electrolytic oxidation (PEO) technique, and the effect of current ratio, C2/C1, ranging from 0.2 to
0.85 on their mechanical and electrochemical properties was investigated. As the C2/C1 ratio
increased, the thickness of the coating layer increased, while surface roughness was almost
unchanged. The hardness and wear resistance had a marked tendency to increase with increasing
C2/C1 ratio and Mg-Al alloy showed higher hardness and wear resistance at all C2/C1 ratios
compared to pure Mg. The weight loss of the pure Mg and Mg-Al alloy in 3.5%NaCl solution was
reduced by coatings. However, it had no dependence on the C2/C1 ratio. The wear resistance of the
coated Mg-Al alloy was better than that of the coated pure Mg.
Effects of MgO Coating on Electrical Properties of BaTiO3
Authors: Park Jae Sung , Han Young Ho
Published: March 2009

Effects of MgO coating on electric properties of BaTiO3 have been studied in terms of
microstructural development and substitution of Mg ion. MgO coated BaTiO3 particles were prepared
by a homogeneous precipitation method and other powders by a conventional mixing method for a
parallel study. MgO coated BaTiO3 exhibited homogeneous microstructure compared with mixed
samples. XRD analysis revealed that Mg substitution for the Ti site in the MgO mixed sample was
much greater than in the coated one. MgO coated BaTiO3 showed higher dielectric constants at the
Curie temperature whereas mixed ones had higher dielectric constants at 60~80. Electrical
properties of MgO mixed and coated BaTiO3 were affected by the diffusion behavior of Mg in
BaTiO3 lattice, which was confirmed by leakage currents.
Rapid Transformation of α-Alumina Nanocomposite Powders by Microwave Assisted Combustion
Authors: Jung Young Mi , Kim Sang Woo
Published: March 2009

The microwave-assisted combustion synthesis as a route to obtain ultrafine α-alumina
and magnesium aluminate composite powders starting from the ammonium aluminum carbonate
hydroxide precursor was investigated. The synthetic temperature and the crystallite size of the α-
alumina nanocomposite powder were significantly affected by the environmental atmosphere in the
microwave assisted combustion. The α-alumina and spinel composite powder was obtained by the
microwave-assisted combustion at temperature of 1000°C under H2/N2, but at 1150°C by the normal
heat process under air. The rapid transformation from γ- to α-phase was achieved by microwave
assisted nucleation at low temperature of 900°C under H2/N2 atmosphere. The least crystallite size
of 26.2 nm was obtained under H2/N2 atmosphere at 1000°C for 10 min.
Effect of Phase Transformation and Fine Particle Dispersion on Densification of High Purity Nanocrystalline γ-Phase Dispersed α-Alumina
Authors: Kim Sang Woo , Kim Shin Young
Published: March 2009

The effect of phase transformation and fine particle dispersion on densification behavior
of high purity nanocrystalline alumina was investigated. The γ/α phase ratio of the mixture
compacts were affected detrimentally by sinterability and phase transformation of α-phase alumina
ceramics. The densification was significantly deteriorated with increasing γ-phase owing to faceted
pores which are caused by the formation of a colony. The faceted pores were not existed in the α-
Al2O3 ceramics with 10% γ-phase. Densification of the 10% γ-phase dispersed α-Al2O3 ceramics
was significantly enhanced by rapid transformation of α-alumina. The grain growth was effectively
inhibited by a small amount of nanoparticle dispersion for the alumina ceramics. As a result, dense
nanostructured alumina can be achieved in the 10% γ-phase dispersed α-Al2O3 ceramics, even
sintering at 1400oC for 3 hours.
Prospects of Potential Semiconductor Spin Detectors
Authors: Chen W.M. , Buyanova I.A. , Oka Y. , Abernathy C.R. , Pearton Stephen J.
Published: March 2009

We review our recent experimental findings by optical orientation spectroscopy that show
efficient spin relaxation within semiconductor spin detectors to be an important factor limiting
efficiency of spin injection in spin light-emitting structures based on ZnCdSe/ZnMnSe and
InGaN/GaMnN. We provide evidence for the physical mechanism responsible for the observed
efficient spin relaxation that accompanies momentum and energy relaxation of excitons/carriers.
These findings call for increasing efforts in suppressing spin relaxation in spin detectors.
Structural and Microwave Properties of Fe-Based Nanopowders via Mechanochemical Synthesis
Authors: Wu Jun Hua , Kong Ling Bing , Kim Young Keun
Published: March 2009

Structural and microwave properties of Fe-based nanoalloy powders, mechanochemically
synthesized with a composition corresponding to Finemet (Fe73.5Si13.5B9Nb3Cu1), were investigated.
The nanopowders, dominated by bcc-Fe (Si), consist of nanocrystallites and display high
magnetization with low-coercivity. The microwave measurements show that the nanocomposites
comprising the nanopowders possess high, broadband magnetic permeability.
Excellent Response of Giant Magnetoimpedance Effect in a Glass-Coated Microwire LC-Resonator
Authors: Le Anh Tual , Kim Chong Oh , Lee Hee Bok
Published: March 2009

A novel excellent response of giant magnetoimpedance effect was found out in a magnetic
LC-resonator consisting of a glass-coated amorphous Co83.2B3.3Si5.9Mn7.6 microwire and two
capacitive cylindrical electrodes at the end of the microwire. The shapes of the impedance curves
plotted vs. applied external dc-field varied dramatically with increasing frequency. The phase angle
was also strongly found to be dependent on this field. The impedance curves were changing abruptly
at near the resonance frequency. Because the permeability of ultra soft magnetic microwire is
changing rapidly as a function of external magnetic field, the resonance frequency as well as
impedance of the LC-resonator also changes drastically with respect to the external magnetic field.
The maximum magnetoimpedance ratio value was reached as much as 1,600%. The sudden changes
of phase angle as much as 180 degree evidenced the occurrence of resonance phenomenon. These
results are promising for developing ultra-high sensitive magnetic sensor applications.
Deep Level Defects in AlxGa1-xN/GaN Heterointerfaces Grown by Molecular Beam Epitaxy
Authors: Jeon Hee Chang , Park Chan Jin , Cho Hoon Young , Kang Tae Won , Kim Tae Whan , Oh Jae Eung
Published: March 2009

Capacitance-voltage (C-V) and Deep-level transient spectroscopy (DLTS) measurements on
AlxGa1-xN/GaN heterostructures were performed to investigate the existence of the carriers and the behavior
of the deep levels in the AlxGa1-xN/GaN heterointerface. The C-V depth profile showed that the carrier
concentration existed at the AlxGa1-xN/GaN heterointerface was 4 × 1012 cm2. The DLTS results showed two
deep levels. The capture cross-section of the deep level related to the two-dimensional electron gas decreased
with increasing depth, resulting from the existence of the different deep levels in each region.
Synthesis of Monodisperse FePt Nanoparticles at a Low Temperature
Authors: Shao Hui Ping , Huang Yu Qiang , Lee Hyo Sook , Suh Yong Jae , Kim Chong Oh
Published: March 2009

Monodisperse FePt nanoparticles were synthesized by thermal decomposition of Fe(CO)5
and reduction of Pt(acac)2 at low temperature of 160–180 °C by using kerosene as a solvent. The
average sizes of the synthesized particles ranged from 2.2 to 4.4 nm. Thermal annealing of the
as-prepared FePt particles at 700 °C for 1 h transformed the crystalline structure of the particles from
a disordered face-centered cubic to an ordered face-centered tetragonal. This change led to a
significant increase in coercivity from 153.37 to 2273.22 Oe and in saturated magnetization from
26.86 to 41.21 emu/g.
Structure and Magnetic Properties of Nanocrystalline Pd-Co and Pd-Co-Fe Layers
Authors: Kovács András , Sato Kazuhisa , Hirotsu Yoshihiko
Published: March 2009

The structure and magnetic properties of sequentially deposited Pd-Co and Pd-Co-
Fe nanocrystals have been investigated by transmission electron microscopy (TEM) and
superconducting quantum interference device magnetometer. The fcc structured PdCo alloy
formation was found in binary Pd-Co nanostructured samples analysed by in situ TEM
annealing. In ternary sample, the addition of Fe to Pd-Co resulted in a complex of Pd and
FeCo nanoparticles. In situ TEM annealing of the ternary sample lead to the formation of L10
ordered phase. It was found that the magnetic properties of the nanoparticles were improved
by Fe addition to the Pd-Co nanoparticles.
Ti-Based Amorphous Alloys and Composites as Potential Candidate Materials for Energy Applications
Authors: Jayalakshmi S. , Kim Ki Bae , Cho Young Whan , Fleury Eric
Published: March 2009

The hydrogenation characteristics and embrittlement behavior of Ti50Zr(50-x)Cux alloys
(x=25,33,40) are reported. The hydrogenation kinetics decreased with increasing Zr-content. Though
the Ti50Zr25Cu25 alloy showed the slowest kinetics, it absorbed large amount of hydrogen (~2.4 wt.%)
and exhibited the best resistance against hydrogen embrittlement. The excellent characteristics of Ti-
Zr-Cu alloys in hydrogen environment indicated that they are promising materials in future for energy
applications.
Advanced Manufacturing Concepts for Crystalline Silicon Solar Cells: Phosphorous Doping and Contact Opening Process
Authors: Park Sang Wook , Cho Eun Chel , Yu Jae Hee , Kim Dea Won
Published: March 2009

In this work, we report on the last investigation of POP (selective Phosphorous doping and
contact Opening Process) in crystalline silicon solar cells. For the industrial solar cells, it must be very
highly doped to decrease the high-contact resistance and not very shallow so that it is not perforated
during paste firing, which would short-circuit the junction. We made improvement involves making
separate diffusions for the different regions since the requirements are so different: a heavily doped
and thick region under the contacts, a thin and lowly doped region under the passivating layer.
Furthermore we opened the metal contact area to make a narrow grid lines simultaneously. As a result
we could increase fill factor and reduce contact resistance by industrial process.
Atomic Arrangement and Formation Mechanism of c-Axis Oriented ZnO Thin Films Grown on p-Si Substrates
Authors: Park N.K. , Lee H.S. , No Y.S. , Kim Tae Whan , Lee Jeong Yong , Choi W.K.
Published: March 2009

The X-ray diffraction (XRD) pattern for the ZnO films grown on Si (100) substrates
indicates that the grown ZnO films have a strong c-axis orientation. The pole figure indicates that
ZnO thin films have columnars with the grains of the [0002] crystallographic axis perpendicular to
the Si (100) substrate, indicative of the random rotational orientations along the c-axis. Selected
area electron diffraction pattern (SADP) of the ZnO/Si (100) heterostructures shows that the ZnO
preferential oriented film is formed on the Si substrate. A possible atomic arrangement of the crystal
structure and the formation mechanism of the c-axis orientated ZnO thin films grown on p-Si
substrates are discussed on the basis of the XRD, the pole figure, and SADP results.
Device Performance of P3HT/C70-Methanofullerene Bulk-Heterojunction Polymer Photovoltaic Cells
Authors: Kim Hee Joo , Lee Kyung , Lee Jong Cheol , Moon Sang Jin
Published: March 2009

In order to more improve the performance of the existing P3HT:C60 polymer photovoltaic
cells, we adopted soluble C70 insteade of C60. The absorption spectra of soluble C70 showed a
significant increase of visible range absorption, resulting in the enhanced photocurrent. To optimize
the device fabrication, we controlled the solvent, concentration of polymer solution and the thickness
of photo-active layer. The best power conversion efficiency obtained in our P3HT:C70 photovoltaic
cells was about 3.0 % under AM 1.5G condition.
Thermoelectric Properties of Co1-xFexSb3 Prepared by Encapsulated Induction Melting
Authors: Park Kwan Ho , Ur Soon Chul , Kim Il Ho
Published: March 2009

Co1-xFexSb3 skutterudites were synthesized by encapsulated induction melting and their
thermoelectric properties were investigated. Single phase δ-CoSb3 was successfully obtained by the
subsequent heat treatment at 773K for 24 hours in vacuum. However, δ-CoSb3 was decomposed to
FeSb2 and Sb when x≥0.3, which means that the solubility limit of Fe to Co is x<0.3. The positive
signs of Seebeck coefficients for all Fe-doped specimens revealed that Fe atoms acted as p-type
dopants by substituting Co atoms. Thermoelectric properties were remarkably enhanced by Fe
doping and optimum composition was found to be Co0.7Fe0.3Sb3 in this study.
Nano Composite Membranes of Branched Sulfonated Poly(Ether Ketone Sulfone) and SiO2 for Fuel Cell Application
Authors: Hong Tae Whan , Lee Dong Hun , Park Hae Suck , Suh Dong Hwan , Kim Whan Gi
Published: March 2009

Branched sulfonated poly(ether ketone sulfone) copolymer was prepared from1,1,1-
tris(4-hydroxyphenyl) ethane, 4,4-difluorophenylsulfone, 3,3'-disodiumsulfonylbenzophenone (40
mol% of bisphenol A) and bisphenol A by polycondensation with the elimination of water in toluene
and NMP at 160) in the presence of anhydrous potassium carbonate. Composite membranes were
successfully cast from the control of organic polymer with SiO2 4-10 wt% of polymer in DMSO.
The films were converted from the salt to acid forms with dilute hydrochloric acid. Organicinorganic
composite membranes for operation in polymer electrolyte membrane fuel cells
(PEMFCs) were characterized and cell-tested. The physico-chemical properties of all membranes
were investigated their thermal properties, water uptake, DSC and thermogravimetric analyzer
(TGA). Branched copolymer and nano composite membranes exhibit proton conductivities from
1.7x10-3 to 8.3x10-3 S/cm2, water uptake from 22 to 26%, IEC from 1.28 to 1.46 meq/g and
methanol diffusion coefficients from 1.2x10-7 to 1.7x10-7 cm2/S.
Catalytic Effect of Ti5Si3 on Dehydrogenation of NaAlH4
Authors: Lee Gil Jae , Shim Jae Hyeok , Cho Young Whan , Lee Kyung Sub
Published: March 2009

Fine Ti5Si3 powder has been synthesized from a mixture of elemental Ti and Si powders using a mechanochemical method. It shows a good catalytic effect on NaAlH4 by reducing the dehydrogenation temperature and improving the dehydrogenation kinetics. Although the catalytic effect of Ti5Si3 is not better than that of TiCl3, the Ti5Si3 catalyst has an advantage over TiCl3 in terms of hydrogen capacity by releasing more hydrogen than TiCl3 during dehydrogenation. NaAlH4 catalyzed with Ti5Si3 shows reversible hydrogen storage by being hydrogenated at moderate conditions, although the hydrogenation kinetics is rather slow.