bluuebunny/crossref_metadata_2025 huggingface dataset:
Droplet Interaction in the Liquid Injection by Multiple Orifices in the Performance of a Venturi Scrubber
Authors: Guerra Vádila Giovana , Daher M.A.F. , Rodrigues M.V. , Gonçalves José Antônio Silveira , Coury José Renato
Published: March 2009

The Venturi scrubber, equipment frequently used in the removal of particles from gases,
is constituted basically by a duct with a convergent section followed by a constriction, or throat,
and a divergent section. A liquid, usually injected in the throat, is atomized by the flowing air at
high speed. The formed droplets act as collectors of particles from the gas. The size and the size
distribution of the droplets inside the equipment are therefore of great importance in the equipment
performance. In the present work, the liquid jet penetration is visualized and the study of the droplet
formation in a rectangular Venturi is carried out. The liquid injection is made through multiple
orifices and the interaction of multiple jets is taken into account. In the experimental tests, the gas
velocity in the throat, the liquid flow rate and the number of orifices for liquid injection were
varied. A Malvern Spraytec aerosol analyzer was used for measuring of the droplet size and size
distribution. The results showed that the liquid jet penetration influences significantly the size of the
formed droplet.
Mechanism Design of ITO-Layer Removal from Color Filter of TFT-LCD
Authors: Pa Pai Shan
Published: March 2009

A mechanism design for the recycling process for removing the ITO-layer from color
filter surface of TFT-LCD is presented. The defect rate of the ITO-layer is easily existent through
the processes of semiconductor production. By establishing a recycling process for the ultra-precise
removal of the thin film microstructure, the semiconductor optoelectronic industry can effectively
recycle defective products, reducing both production costs and pollution. In the current experiment,
the major interest is the design mechanism features of the removal process for a thin layer of ITO.
For the recycling processes, a high flow velocity of the electrolyte provides a larger discharge
mobility and a better removal effect. A thin thickness of the negative-electrode, an adequate gapwidth
between the negative-electrode and the workpiece, or a higher working temperature
corresponds to a higher removal rate for the ITO-layer. An adequate feed rate of the color filter
combined with enough electric power produces a fast removal rate. An effective mechanism design
and a low-cost recycling process using the electrochemical removal requires quite a short time to
make the ITO layer remove easily and cleanly.
Finite Element Prediction of Stack-Die Packages under Board Level Drop Test
Authors: Hsu Hsiang Chen , Hsu Yu Chia , Yeh Chan Lin , Lai Yi Shao
Published: March 2009

The objective of this research is to investigate the solder joint reliability of board-level drop
test based on the support excitation scheme incorporated with the submodel technique for stacked-die
packages. Three lead-free materials, SAC405 (Sn4Ag0.5Cu), SAC355(Sn3.5Ag0.5Cu) and Sn3.5Ag
were used to demonstrate the transient dynamic response for solder balls subject to JEDEC
pulse-controlled board-level drop test standard. In order to evaluate the structure of the interested
area, a strip model sliced from the full test vehicle is used in this research. In addition, the submodel
region is particularly chosen with strip model by performing the cut boundary interpolation. The
envelope of equivalent stress for the outermost solder joint off the end of the strip model is plot to
show the potential failure mode and mechanism. The cut boundary of submodel is verified and the
mesh density of submodel is examined. For a refinery mesh of submodel, parametric studies for
structure and material are carried out to investigate the reliability of the outermost solder joint, and the
results are summarized as design rules for the development of stacked-die packages.
A Study of Cutting Temperatures in Turning of Glass Fiber Reinforced Plastics Materials
Authors: Chang Chung Shin , Hwang Lih Ren , Hsue Albert Wen Jeng
Published: March 2009

Nine kinds of chamfered main cutting edge carbide tools were used in turning of
high-strength glass-fiber-reinforced plastics (GFRP) materials to study the temperature of tip's
surface and the cutting forces. Force data from these tests were used to estimate the empirical
constants of the mechanical model and verify its prediction capabilities. The friction forces and
frictional heat generated on elementary cutting tools are calculated by using the measured cutting
forces and the oblique cutting analysis. The heat partition factors between the tip and chip are
solved by using the inverse heat transfer analysis, which utilizes temperature on the carbide tip’s
surface measured by infrared as the input. The tip’s surface temperature of the carbide is solved
by finite element analysis (FEA) and compared with those obtained from experimental
measurements. A good agreement demonstrates the accuracy of the proposed model.
Study on Dendrite Shapes of Solidification in an Undercooled Melt
Authors: Ho Ching Yen , Lee Yi Chwen , Shih Chia Sheng
Published: March 2009

Dendrite needles grow from an undercooled melt and their shapes depend on the
temperature distribution on the solidification front, which are specified by some parameters such as
undercooling, capillary length, diffusivity, convection and kinetic effects. Neglecting the convection
and kinetic effects, this study numerically computes the quasi-steady-state integral-differential
equation to obtain the shape of a dendrite using solvability condition and investigates the effect of
parameters changing the temperature field on the shape of a dendrite. The results reveal that the tip
shape enlarges with the decreasing undercooling and increasing capillary length. On the other hand,
the increase of thermal diffusivity only slightly reduces the tip radius and shape of a dendrite.
Stylus Measurement and Error Analysis of Large Slope Angle Lens
Authors: Chen Chao Chang Arthur , Lin Chih Ching , Chen Rung
Published: March 2009

Contact stylus instrument has difficulties in tracing large slope angle (LSA) lens
for surface profile measurement due to the dilation of measured profile image by the shape of
stylus tip. This research is to develop a surface profile reconstruction method for tip profile with
LSA lens and then verified the result by estimating the form error. Experimental set-up is
configured of a surface profile and roughness analyzer, Panasonic Ultra Accuracy 3-D
Profilometer (UA3P), and the feasibility of the developed program is compared with the results
of a commercial operation software, UA3P software. The figure form error (FFE) is used to
evaluate the developed method. Experiments have been performed by measuring the LSA lens
of a s55ml spherical gage with measuring ranges increasing from ±30°, ±45° to ±60° and
measuring an aspheric lens with range ±50°. Experimental results showed that the FFE of the
developed method has smaller FFE values than those obtained by the UA3P software as the
measuring range of ±30° and ±45. Similar result of FFE is obtained as 0.891 μm for the
aspheric lens by the developed method than FFE 0.896 μm by the UA3P software. Therefore, the
developed method has been verified for estimating the FFE of LSA lens with variant measuring
ranges. Future work is to develop related compensation methodology of FFE for LSA lens
measurement and also to find appreciated tip profiles for measuring LSA lens of higher order
nonlinear terms.
Experiment Study and Numerical Analysis of Flow and Heat Transfer in (110) Silicon Base Microchannel
Authors: Tsai Sheng Hong , Chen Yu Tang
Published: March 2009

Microchannel heat sink is fabricated on silicon wafer by anisotropic etching, and used
Pyrex #7740 as a transparent cover that integrated by anodic bonding. Rectangular microchannel
presents the flow phenomena of fluid in micro scale, and this study focus on the boundary
conditions which hydraulic diameter (Dh) is from 80m to 350m and Aspect ratio is from 0.24~7.8
of working fluid (DI water). While the size of microchannel is decreasing, laminar flow occurs on
the low Reynolds number, which caused by the interaction of viscosity and friction on boundary
layer. Sequentially, the influence of dimension decreasing on microchannel that induced transition
and turbulent flow in early stage as Reynolds number is still in the range of 600~800. Pressure drop
is high (2 bar) when fluid flows through the micro channel, and flux is constrained by the flow
resistance during experiment operating. In this study, it takes effect by increasing aspect ratio to
reduce pressure drop and enlarge the conductive surface. Geometry of microchannel, hydraulic
diameter, and aspect ratio are the key factors in flow phenomena investigation. This research
presents the difference between micro scale flow and traditional pipe flow by consideration of
Reynolds number.
By using computer aided engineering to optimize the aspect ratio of microchannel, which can find
the maximum conductive surface under the limitation of pressure drop. The best value of aspect
ratio is 0.88~1.22. The simulation result makes good sequence with experiment data. Based on this
methodology, numerical analysis can be used to design the optimal microchannel on wafer for
cooling hot spot.
Electrical Contact Resistance Approach to Tribological Properties of Artificial Joints
Authors: Chang Yuh Ping , Wang Ruei Hong , Hung Yu Yang , Chou Huann Ming , Wang Jin Chi
Published: March 2009

The tribo-electrification mechanisms had been successfully applied to dynamic monitor
the tribological properties between the metal films by our laboratory members. Moreover, the novel
method of using continuous tribo-electrification variations for monitoring showed more sensitive
and discriminative than that by the continuous friction coefficient variations as usual. However, the
above method is only suitable for the conducted material pairs.
This study is based on the above views to further develop another novel method for dynamic
monitoring the tribological properties between the semiconductor films in the friction process. The
experiment was conducted by the self-developed friction tester and its measure system. The
continuous variations of electrical contact resistance and friction coefficient were measured for
monitoring the timings of film rupture between the semiconductor films. Moreover, the wear loss
was measured by an accuracy balance and the SEM was used to observe the structures of material
transfer. Therefore, the wear mechanisms of Ti sliding against Ti with TiO2-film under different
normal loads can be investigated.
According to the experimental results of this study, the novel method of using electrical contact
resistance variations does show great potentialities for dynamic monitoring the tribological
properties of the TiO2-film.
Agent-Based Integrated and Collaborative Engineering Asset Management
Authors: Hsiao David W. , Trappey Amy J.C. , Ma Lin , Fan Yat Chih , Mao Yen Chieh
Published: March 2009

Engineering assets are fundamentally important to enterprises. Thus, making the best use
of engineering assets attracts equipment and system engineers’ attention. The state-of-the-art
researches contribute to asset condition monitoring, asset symptom diagnosis, asset health prognosis,
and the integration of above knowledge. However, they still lack the combination with enterprise
resources to determine the best maintenance/renewal time for the optimization of total enterprise
benefits. Consequently, this paper proposes the integrated architectural framework, activity and
process models of a multi-agent system called agent-based integrated engineering asset management
(AIEAM) based on agent techniques to build collaborative environment for asset manager, diagnosis
expert, prognosis expert and enterprise resource manager. An engineering asset management case (for
repair and maintenance of automatic parking tower) applying the proposed architecture and models is
depicted in the paper.
Ternary and Quaternary Interdiffusion in γ (fcc) Fe-Ni-Cr-X (X = Si, Ge) Alloys at 900°C
Authors: Garimella N. , Brady M.P. , Sohn Yong Ho
Published: March 2009

Interdiffusion in Fe-Ni-Cr (fcc γ phase) alloys with small additions of Si and Ge at 900°C
was studied using solid-to-solid diffusion couples. Alloy rods of Fe-24 at.%Ni, Fe-24 at.%Ni-
22at.%Cr, Fe-24 at.%Ni-22at.%Cr-4at.%Si and Fe-24 at.%Ni-22at.%Cr-1.7at.%Ge were cast using
arc-melt, and homogenized at 900°C for 168 hours. Sectioned alloy disks from the rods were
polished, and diffusion couples were assembled with in Invar steel jig, encapsulated in Argon after
several hydrogen flushes, and annealed atz 900°C for 168 hours. Polished cross-sections of the
diffusion couples were characterized to determine experimental concentration profiles using
electron probe microanalysis with pure elemental standards. Interdiffusion fluxes of individual
components were calculated directly from the experimental concentration profiles, and the moments
of interdiffusion flux profiles were examined to determine the average ternary and quaternary
interdiffusion coefficients. Effects of alloying additions on the interdiffusional behavior of Fe-Ni-
Cr-X alloys at 900°C are presented with due consideration for the formation of protective Cr2O3
scale.
Normally-Off 4H-SiC Vertical JFET with Large Current Density
Authors: Shimizu Haruka , Onose Yasuo , Someya Tomoyuki , Onose Hidekatsu , Yokoyama Natsuki
Published: March 2009

We developed normally-off 4H-SiC vertical junction field effect transistors (JFETs) with
large current density. The effect of forming an abrupt junction between the gate and the channel was
simulated, and vertical JFETs were then fabricated with abrupt junctions. As a result, a large rated
drain current density (500 A/cm2) and a low specific on-resistance (2.0 mWcm2) were achieved for
small devices. The blocking voltage was 600 V. These results were due to a reduction of the threshold
voltage by forming the abrupt junction between the gate and the channel.
Silicon Carbide Differential Amplifiers for High-Temperature Sensing
Authors: Patil Amita , Fu Xiao An , Neudeck Philip G. , Beheim Glenn M. , Mehregany Mehran , Garverick Steven
Published: March 2009

This paper presents silicon carbide sensor interface circuits and techniques for MEMSbased
sensors operating in harsh environments. More specifically, differential amplifiers were
constructed using integrated, depletion-mode, n-channel, 6H-SiC JFETs and off-chip passive
components. A three-stage voltage amplifier has a differential voltage gain of ~50 dB and a gainbandwidth
of ~200 kHz at 450oC, as limited by test parasitics. Such an amplifier could be used to
amplify the signals produced by a piezoresistive Wheatstone bridge sensor, for example. Design
considerations for 6H-SiC JFET transimpedance amplifiers appropriate for capacitance sensing and
for frequency readout from a micromechanical resonator are also presented.
Development of a High Rate 4H-SiC Epitaxial Growth Technique Achieving Large-Area Uniformity
Authors: Ito Masahiko , Storasta L. , Tsuchida Hidekazu
Published: March 2009

A vertical hot-wall type epi-reactor that makes it possible to simultaneously achieve both a high rate of epitaxial growth and large-area uniformity at the same time has been developed. A maximum growth rate of 250 µm/h is achieved at 1650 °C. Thickness uniformity of 1.1 % and doping uniformity of 6.7 % for a 65 mm radius area are achieved while maintaining a high growth rate of 79 µm/h. We also succeeded in growing a 280 µm-thick epilayer with excellent surface morphology and long carrier lifetime of ~1 µs on average. The LTPL spectrum shows free exciton peaks as dominant, and few impurity-related or intrinsic defect related peaks are observed. The DLTS measurement for an epilayer grown at 80 µm/h shows low trap concentrations of 1.2×1012 cm-3 for Z1/2 center and 6.3×1011 cm-3 for EH6/7 center, respectively.
(11-20) Face Channel MOSFET with Low On-Resistance
Authors: Okuno Eiichi , Endo Takeshi , Kawai Jun , Sakakibara Toshio , Onda Shoichi
Published: March 2009

We have investigated the techniques to improve the channel mobility of SiC MOSFETs
and found that the hydrogen termination of dangling bonds at a MOS interface is very effective in
improving the channel mobility, particularly that of the interface fabricated on a (11-20) face wafer. A
high channel mobility of MOSFET on the (11-20) face was achieved to 244cm2/Vs by new process
which can terminate dangling bonds by hydrogen. The vertical MOSFET, which is prepared using this
process, has a low on-resistance of 5.7 mΩcm2 and a breakdown voltage of 1100 V. The channel
resistance is estimated at 0.58 mΩcm2.
Effect of Recombination-Induced Stacking Faults on Majority Carrier Conduction and Reverse Leakage Current on 10 kV SiC DMOSFETs
Authors: Ryu Sei Hyung , Husna Fatima , Haney Sarah K. , Zhang Qing Chun Jon , Stahlbush Robert E. , Agarwal Anant K.
Published: March 2009

This paper presents the effect of recombination-induced stacking faults on the drift based
forward conduction and leakage currents of high voltage 4H-SiC power devices. To show the effects,
IV characteristics of a 4H-SiC 10 kV DMOSFET and a 4H-SiC 4 kV BJT have been evaluated before
and after the induction of stacking faults in the drift epilayer. For both devices, significant increases in
forward voltage drops, as well as marked increases in leakage currents have been observed. The
results suggest that injection of minority carriers in majority carrier devices should be avoided at all
times.
950 Volt 4H-SiC MOSFETs: DC and Transient Performance and Gate Oxide Reliability
Authors: Matocha Kevin , Stum Zachary , Arthur Steve , Dunne Greg , Stevanovic Ljubisa
Published: March 2009

SiC vertical MOSFETs were fabricated and characterized to achieve a blocking voltage of
950 Volts and a specific on-resistance of 8.4 mW-cm2. Extrapolations of time-dependent dielectric
breakdown measurements versus applied electric field indicate that the gate oxide mean-time to
failure is approximately 105 hours at 250°C.
Very High Growth Rate of 4H-SiC Using MTS as Chloride-Based Precursor
Authors: Pedersen Henrik , Leone Stefano , Henry Anne , Beyer Franziska Christine , Darakchieva Vanya , Janzén Erik
Published: March 2009

The chlorinated precursor methyltrichlorosilane (MTS), CH3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall CVD reactor, with growth rates as high as 170 µm/h at 1600°C. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor up to about 100 µm/h. The growth rate dropped for C/Si < 1 but was constant for C/Si > 1. Further, the growth rate decreased with lower Cl/Si ratio.
A Simple and Reliable Electrical Method for Measuring the Junction Temperature and Thermal Resistance of 4H-SiC Power Bipolar Junction Transistors
Authors: Eriksson K.G.P. , Domeij Martin , Lee Hyung Seok , Zetterling Carl Mikael , Östling Mikael
Published: March 2009

To determine the maximum allowed power dissipation in a power transistor, it is important
to determine the relationship between junction temperature and power dissipation. This work presents
a new method for measuring the junction temperature in a SiC bipolar junction transistor (BJT) that is
self-heated during DC forward conduction. The method also enables extraction of the thermal
resistance between junction and ambient by measurements of the junction temperature as function of
DC power dissipation. The basic principle of the method is to determine the temperature dependent
I-V characteristics of the transistor under pulsed conditions with negligible self-heating, and compare
these results with DC measurements with self-heating. Consistent results were obtained from two
independent temperature measurements using the temperature dependence of the current gain, and the
temperature dependence of the base-emitter I-V characteristics, respectively.
12 kV 4H-SiC p-IGBTs with Record Low Specific On-Resistance
Authors: Zhang Q. Jon , Jonas Charlotte , Sumakeris Joseph J. , Agarwal Anant K. , Palmour John W.
Published: March 2009

DC characteristics of 4H-SiC p-channel IGBTs capable of blocking -12 kV and conducting -0.4
A (-100 A/cm2) at a forward voltage of -5.2 V at 25°C are demonstrated for the first time. A record
low differential on-resistance of 14 mW×cm2 was achieved with a gate bias of -20 V indicating a
strong conductivity modulation in the p-type drift region. A moderately doped current enhancement
layer grown on the lightly doped drift layer effectively reduces the JFET resistance while maintains
a high carrier lifetime for conductivity modulation. A hole MOS channel mobility of 12.5 cm2/V-s
at -20 V of gate bias was measured with a MOS threshold voltage of -5.8 V. The blocking voltage
of -12 kV was achieved by Junction Termination Extension (JTE).
4H-SiC Single Photon Avalanche Diode for 280nm UV Applications
Authors: Hu Jun , Xin Xiao Bin , Alexandrov Peter , Zhao Jian Hui , VanMil Brenda L. , Gaskill D. Kurt , Lew Kok Keong , Myers-Ward Rachael L. , Eddy Charles R.
Published: March 2009

This paper reports a 4H-SiC single photo avalanche diode (SPAD) operating at the solar
blind wavelength of 280 nm. The SPAD has an avalanche breakdown voltage of 114V. At 90% and
95% of the breakdown voltage, the SPAD shows a low dark current of 57.2fA and 159fA,
respectively. The quantum efficiency of 29.8% at 280nm and <0.007% at 400nm indicates a high
UV-to-visible rejection ratio of >4300. Single photon counting measurement at 280nm shows that a
single photon detection efficiency of 2.83% with a low dark count rate of 22kHz is achieved at the
avalanche breakdown voltage of 116.8V.
Effects of 3C-SiC Intermediate Layer on the Properties of AlN Films Grown on SiO2/Si Substrate
Authors: Chung Gwiy Sang , Lee Tae Won
Published: March 2009

Aluminum nitride thin films were deposited on polycrystalline 3C-SiC intermediate layer
by pulsed reactive magnetron sputtering system. Characteristics of AlN/SiC structures were
investigated experimentally by means of FE-SEM, AFM, X-ray diffraction, and FT-IR. The columnar
structure of AlN thin films was observed by FE-SEM. The surface roughness of AlN films on 3C-SiC
layer was measured using AFM. X-ray diffraction pattern of AlN films on SiC layers highly were
oriented as (002). Full width of half maximum (FWHM) of the rocking curve around (002) reflections
was 1.3°. It was determined from infrared absorbance spectrum that the residual stress of AlN thin
films grown on SiC layers was almost free. The presented results show that AlN thin films on 3C-SiC
buffer layers can be used for various applications.
Multi-Level Simulation Study of Crystal Growth and Defect Formation Processes in SiC
Authors: Takaba Hiromitsu , Sagawa Ai , Sato Miki , Ouchi Seika , Yoshida Yuko , Hayashi Yukie , Sato Emi , Inaba Kenji , Sahnoun Riadh , Koyama Michihisa , Tsuboi Hideyuki , Hatakeyama Nozomu , Endou Akira , Kubo Momoj , Del Carpio Carlos A. , Kito Yasuo , Makino Emi , Hosokawa Norikazu , Hasegawa Jun , Onda Shoichi , Miyamoto Akira
Published: March 2009

The mechanism of layer growth as well as defect formation in the SiC crystal is fundamentally important to derive its appropriate performance. The purpose of the present study is to investigate competitive adsorption properties of growth species on the various 4H-SiC polytype surfaces. Adsorption structure and binding energy of growth species in the experimentally condition on various SiC surfaces were investigated by density functional theory. For the SiC(000-1) and SiC(0001) surfaces, the adsorption energy by DFT follows the orders C > H > Si > SiC2 > Si2C > C2H2. Furthermore, based on the DFT results, amount of adsorption of each species in the experimental pressure condition were evaluated by grand canonical Monte Carlo method. H and Si are main adsorbed species on SiC(0001) and SiC(000-1) surfaces, respectively. The ratio of amount of adsorption of Si to H was depending on the surface structure that might explain different growth rate of the surfaces.
Current Collapse in AlGaN/GaN/AlGaN Double Heterojunction Field Effect Transistors
Authors: Shimizu Mitsuaki , Inada Masaki , Yagi Shuichi , Nakajima Akira , Okumura Hajime , Ubukata Akinori , Yano Yoshiki , Akutsu Nakao
Published: March 2009

The current collapse of normally-off mode AlGaN/GaN/AlGaN double heterojunction
field effect transistors was investigated in comparison with the normal AlGaN/GaN heterojunction
filed effect transistors.
Electrical Properties of Inhomogeneous Pt/GaN Schottky Barrier
Authors: Roccaforte Fabrizio , Iucolano Ferdinando , Giannazzo Filippo , Di Franco Salvatore , Puglisi Valeria , Raineri Vito
Published: March 2009

In this work, the electrical properties of Pt/GaN Schottky contacts were studied. The
temperature dependence of the barrier height and ideality factor, and the low experimental value of
the Richardson’s constant, were discussed considering the formation of an inhomogenous Schottky
barrier. Local current-voltage measurements on Pt/GaN contact, performed with a conductive
atomic force microscope, demonstrated a Gaussian distribution of the local barrier height values and
allowed to monitor the degree of inhomogeneity of the barrier. The presence of defects, terminating
on the bare GaN surface, was correlated with the electrical behavior of the inhomogeneous barrier.
Effect of Deep Trap on Breakdown Voltage in AlGaN/GaN HEMTs
Authors: Nakajima Akira , Yagi Shuichi , Shimizu Mitsuaki , Okumura Hajime
Published: March 2009

The effect of AlGaN surface traps on breakdown voltage VB and drain current collapse in
AlGaN/GaN high electron mobility transistors (HEMTs) were investigated using experimental
measurement and numerical simulation. The drain current transient due to surface traps was
systematically measured and analyzed, and the activation energy of a surface trap was evaluated as
approximately 0.7 eV. Results from the device simulation of VB in HEMTs were in good agreement
with the experimental results when assuming surface traps. The results indicate that surface traps
increase VB, and induce a crucial current collapse.
Diamond Doped by Hot Ion Implantation
Authors: Tsubouchi Nobuteru , Ogura M. , Watanabe H. , Chayahara Akiyoshi , Okushi Hideyo
Published: March 2009

Multiple P or S hot ion implantation to diamond substrates was performed at 800°C.
Optical absorption spectra indicated that instantaneous annealing during hot ion implantation occurs.
Temperature dependence of resistance demonstrated that a P as-implanted sample using a
homoepitaxial diamond film substrate emerges a weak doping effect. Also on S implantation, a
presence of a weak doping effect was observed in an as-implanted sample, but it was suggested that
the dopant is not S itself but S and defect complex. However, post-implantation annealing resulted in
high resistance of the samples and missing of such weak doping effects.
Homoepitaxial Growth of 4H-SiC by Hot-Wall CVD Using BTMSM
Authors: Seo Han Seok , Song Ho Geun , Moon Jeong Hyun , Yim Jeong Hyuk , Oh Myeong Sook , Lee Jong Ho , Choi Yu Jin , Kim Hyeong Joon
Published: March 2009

Homoepitaxial growth of 4H-SiC epilayer by hot-wall chemical vapor deposition using bis-trimethylsilylmethane (BTMSM, C7H20Si2) precursor was investigated. The growth rate of 4H-SiC was investigated as a function of the growth temperature and source flow rate. The FWHM values of epilayers as the growth temperature and source flow rate also investigated. The growth rate of 4H-SiC epilayer grown by hot-wall CVD was 3.0 μm/h and the background doping level of 4H-SiC epilayer was mid 1015/cm3.
Nitrogen Doping in Low-Temperature Halo-Carbon Homoepitaxial Growth of SiC
Authors: Chindanon Krista , Lin Huang De , Melnychuk Galyna , Koshka Yaroslav
Published: March 2009

In this work, nitrogen doping was investigated during the low-temperature halo-carbon epitaxial growth of 4H-SiC on Si- and C-faces. The dependencies of nitrogen incorporation on nitrogen flow rate, Si/C ratio, growth rate, and temperature were investigated. It was established that the efficiency of nitrogen incorporation for the C-face growth at 1300 °C is higher than that for the Si-face for a wide range of the growth conditions. Seeming deviation of the Si/C ratio dependence from the “site-competition” trend confirmed the critical role of the silicon vapor condensation during the low-temperature epitaxy. Opposite trends for the nitrogen doping dependence on the growth rate were observed on the Si- and C-faces. Finally, a complex temperature dependence of the nitrogen doping in the temperature range from 1300 to 1450 0C was observed.
Micropipe Dissociation through Thick n+ Buffer Layer Growth
Authors: MacMillan Mike F. , Sanchez Edward , Dudley Michael , Chen Yi , Loboda Mark J.
Published: March 2009

Thick (> 25 µm) 4H n+ epitaxial layer growth was performed on 4H n+ substrates utilizing chlorine containing etch chemistries in a hot wall CVD system. Optimization of the n+ epitaxial layer growth was achieved by varying C/Si ratio and N2 flow. Desired epitaxial layers have doping levels > 5x1018 cm-3, epitaxial surface roughness <10 nm on a 20x20 µm area and overall micropipe density reduction. To confirm the conversion of micropipes into closed core screw dislocations, microscopic examination of the epitaxial and wafer surfaces was carried out after KOH etching. Grazing incidence x-ray topography (XRT) as well as cross sectional XRT and microscopy were also performed. The cross sectional evaluation showed that the dissociation of the micropipes occurs very close to the epitaxy/wafer interface.
Solution Growth of 3C-SiC on 6H-SiC Using Si Solvent under N2-He Atmosphere
Authors: Kusunoki Kazuhiko , Kamei Kazuhito , Yashiro Nobuyoshi , Tanaka Takashi , Yauchi Akihiro
Published: March 2009

Top seeded solution growth of SiC on on-axis 6H-SiC was performed using Si solvent at growth temperature as high as 1645-1870°C. It was found that different polytypes of SiC layers were grown on 6H-SiC depending on gas species during growth. The growth under He atmosphere produced 6H-SiC homoepitaxial layers. On the other hand, the growth under N2-He atmosphere led to 3C-SiC epitaxial layers. It was obvious that the nitrogen dissolved in solvent strongly favoured the 3C-SiC polytype formation on 6H-SiC. We also conducted characterization of 3C-SiC layers grown on 6H-SiC (0001)Si by TEM, molten KOH etching and precise XRD measurement.
Growth of 3C-SiC on Si: Influence of Process Pressure
Authors: Severino Andrea , Frewin Christopher L. , Anzalone Ruggero , Bongiorno Corrado , Fiorenza Patrick , D'Arrigo Giuseppe , Giannazzo Filippo , Foti Gaetano , La Via Francesco , Saddow Stephen E.
Published: March 2009

In this work a comparison between atmospheric pressure (AP) and low pressure (LP) carbonization as the first step in the growth process of 3C-SiC on Si substrates is presented. Three different Si substrate orientations have been studied and compared. Characterization analysis has been performed by Atomic Force Microscopy (AFM), X-ray Diffraction Spectroscopy (XRD) and Transmission Electron Microscopy (TEM). XRD and AFM analysis show a lower roughness and a better quality for LPCVD carbonized samples. Substrate orientation plays an important role both in the generation as well as in the effect of such defects in the subsequent growth process, leading to a rougher SiC surface for growth on (110) Si while micro-twin effects are limited for growth on (111) Si, resulting in an extremely flat film.
3C-SiC on Si Substrates Using Pendeo-Epitaxial Growth
Authors: Kim Byeung C. , Capano Michael A.
Published: March 2009

Cubic silicon carbide (3C-SiC) growth using Pendeo-epitaxy technique was successfully achieved on Si(001) substrates. 3C-SiC was grown by chemical vapor deposition (CVD) with silane and propane as precursors. Effects of underlying stripes and seed 3C-SiC layers thickness on PE 3C-SiC films were investigated. Root mean square (RMS) measurements using atomic force microscope (AFM) showed that surface morphology of PE 3C-SiC films remarkably improves with an increase of the seed 3C-SiC layer thickness, and the values were from 9.8 nm for 3 µm thick seed layer to 0.5 nm for 10 µm thick seed layer thickness. Additionally, domain boundary densities were counted, and the values also strongly depend on the seed layer thickness: from >1500/mm2 for 3 µm seed layer thickness to <100/mm2 for 10 µm seed layer thickness. Pendeo-epiaxial growth profiles with various width/separation dimensions of stripes were also investigated, and stripes with width of 10 µm and separation of 5 µm provide the best profile and process viability.
Heteroepitaxial Growth of 3C-SiC on Si (111) at Low Substrate Temperature by Plasma Assisted CVD
Authors: Shimizu Hideki , Kato Akira
Published: March 2009

In order to demonstrate the formation of 3C-SiC film on Si (111) at low substrate temperature, the effects of C3H8 on the crystallinity of the films on Si (111) have been investigated by changing the flow rate of C3H8 at the substrate temperature of 950 °C. Nearly single-crystalline 3C-SiC film grew under the ratio of the flow rate of C3H8 to the flow rate of SiH4 (C/Si) of 2 - 2.5. From these results, it is suggested that C/Si shifts into higher with decreasing the substrate temperature. The crystallinity has been investigated by a reflection electron diffraction (RED) and a X-ray diffraction (XRD). The thickness and the surface roughness of the films were investigated by an ellipsometric measurement.
Atomic and Electronic Structure of the (2×1) and c(2×2) 4H-SiC(1-102) Surfaces
Authors: Virojanadara Charíya , Hetzel M. , Johansson Leif I. , Choyke Wolfgang J. , Starke Ulrich
Published: March 2009

The atomic and electronic structure of 4H-SiC(1 1 02) surfaces were investigated using
scanning tunneling microscopy (STM), low-energy electron diffraction (LEED) and photoemission
(PES). Two well ordered phases existing on this surface, i.e. (2×1) and c(2×2) are discussed. The
(2×1) phase consists of a Si adlayer which is topped by an array of ordered Si-nanowires with
electronic states confined to one dimension. For the c(2×2) phase STM indicates the presence of
adatoms and PES a surface composition close to bulk SiC stoichiometry. A detailed atomic model
for this c(2×2) phase is proposed.
Dislocation Contrast of 4H-SiC in X-Ray Topography under Weak-Beam Condition
Authors: Yamaguchi Hirotaka , Matsuhata Hirofumi , Nagai Ichiro
Published: March 2009

We have investigated dislocation image of 4H-SiC wafers projected on synchrotron
X-ray topographs taken under different positions in the rocking curve of a diffraction peak. The
diffraction geometry was grazing-incidence extremely asymmetric and the diffraction vectors were
g = 1 1 2 8 and 112 8. The weak-beam images were demonstrated for basal-plane dislocations
and threading-screw dislocations. The basal-plane dislocation images became narrower in width
at the off-Bragg conditions, and they were decomposed to separate lines under the weak-beam
condition. The threading-screw dislocations showed changes in their shape and contrast as the
crystal set was tilted from the rocking-curve peak, and finally the characteristic images near the
dislocation core were observed under the weak-beam condition. The origin of these weak-beam
images is unclear, but it will offer detailed analysis of the dislocations.
Evolution of Basal Plane Dislocations during 4H-SiC Epitaxial Growth
Authors: Stahlbush Robert E. , VanMil Brenda L. , Liu Kendrick X. , Lew Kok Keong , Myers-Ward Rachael L. , Gaskill D. Kurt , Eddy Charles R. , Zhang X. , Skowronski Marek
Published: March 2009

The evolution of basal plane dislocations (BPDs) in 4H-SiC epitaxy during its growth is
investigated by using two types of interrupted growth in conjunction with ultraviolet
photoluminescence (UVPL) imaging of the dislocations. For the first, each epitaxial growth was
stopped after 10-20 μm and a UVPL map was collected. For the second, changing the gas flow
interrupted the growth and the BPDs were imaged at the end. The first sequence made it possible to
track the formation of half-loop arrays and show that they arise from BPDs that glide perpendicular to
the offcut direction. For both types, each interruption causes between 30 – 50% of the BPDs to be
converted to threading edge dislocations (TEDs). This result suggests that using interrupted growth
may be an alternate method to producing epitaxial layers with low BPD concentration.
Characterization of Dislocations and Micropipes in 4H n+ SiC Substrates
Authors: Wu Ping , Yoganathan Murugesu , Zwieback Ilya , Chen Yi , Dudley Michael
Published: March 2009

Etching of 4H-SiC wafers in molten KOH as a method for micropipe and dislocation
density analysis was investigated. The obtained results were correlated with those of the synchrotron
white beam x-ray topography. Heavily nitrogen-doped SiC shows a significantly different etching
behavior in comparison with the low-doped material. This complicates identification of different
types of threading defects. In particular, it is difficult to separate Threading Screw Dislocations
(TSD) from Threading Edge Dislocations (TED). Depending on the level of doping and thermal
history of the crystal, some of the etch pits emerging due to the 1c screw dislocations can be as large as
those due to the micropipes.
X-Ray Rocking Curve Characterization of SiC Substrates
Authors: Yoganathan Murugesu , Wu Ping , Zwieback Ilya
Published: March 2009

X-ray rocking curve characterization is a relatively fast and nondestructive technique that
can be utilized to evaluate the crystal quality of SiC substrates. The contribution of lattice curvature
to rocking curve broadening is estimated, and shown to be the major contribution to the measured
broadening (FWHM). The feedback on lattice quality is used to optimize our SiC growth process. In
the optimized growth runs, the typical variation in rocking curve sample angle Ω across the entire 3”
diameter wafer is about 0.2 degrees. Possible mechanisms leading to changes in the lattice curvature
are discussed.
TEM Observation of the Polytype Transformation of Bulk SiC Ingot
Authors: Aoki Masahiko , Miyazaki Megumi , Nishiguchi Taro , Kinoshita Hiroyuki , Yoshimoto Masahiro
Published: March 2009

This article describes the analysis of the polytype transformation of SiC ingot. We analyzed
the sample by Raman spectroscopy and TEM observation. The result of the analysis shows the
polytype is transformed from 4H-SiC to 6H-SiC, and then returned to 4H-SiC. We found that the
direction of the c-axis is not the same as the growth direction of the ingot. And also we found the
existence of 8H-SiC at the interface between 6H-SiC and 4H-SiC region by the selected area
diffraction pattern and confirmed it by HR-TEM observation.
Investigation of Pits Formed at Oxidation on 4H-SiC
Authors: Nakano Yuki , Nakamura T. , Kamisawa A. , Takasu H.
Published: March 2009

We report an experimental investigation of the pits formed at oxidation. The pits were
formed by a long time oxidation in a dry or wet atmosphere at high temperature (~ 1200 oC).
Although they were observed in (0001) face, they were not in (000-1) face. Comparing the points of
oxidation pits to those of molten KOH etching pits on the same area of the substrate, we show that
the oxidation pits are formed by oxidizing defects. In addition, the influence of the oxidation pits to
the reliability of thermal oxide was researched.
Wave-Function Symmetry and the Properties of Shallow P Donors in 4H SiC
Authors: Ivanov Ivan G. , Persson C. , Henry Anne , Janzén Erik
Published: March 2009

A new investigation on the optical properties of the phosphorus-bound excitons is
presented. Arguments are given in favor of the possibility of degenerate donor state for phosphorus
substituting Si atom on hexagonal site. On the base of a simple model, it is shown that the
experimental spectra also provide evidence in favor of this possibility. The possibility for violation of
the Haynes rule in the case of phosphorus donors on the two inequivalent sites is indicated.
Diffusion and Electroluminescence Studies of Low Temperature Diffusion of Boron in 3C-SiC
Authors: Atabaev I.G. , Tin Chin Che , Atabaev B.G. , Saliev T.M. , Bakhranov E.N. , Matchanov N.A. , Lutpullaev S.L. , Zhang J. , Saidkhanova N.G. , Yuzikaeva F.R. , Nuritdinov I. , Islomov A. Kh. , Amanov M.Z. , Rusli Rusli , Kumta A.
Published: March 2009

The characteristics of boron diffusion in 3C-SiC at low temperature have been measured
using spreading resistance technique and electroluminescence spectroscopy. The coefficient of boron
diffusion in the temperature range of 1150 –1250°С has been found to be about 5.5 x 10-11–5.0 x 10-10
cm2/sec and the activation energy of boron diffusion was determined to be about 0.9 –1.15 eV.
Electroluminescence spectra of 3C-SiC p-n junction structures showed peaks at 750 and 630 nm due
to growth defects and carbon-silicon divacancies respectively.
Impact of 4H-SiC Substrate Defectivity on Epilayer Injected Carrier Lifetimes
Authors: Myers-Ward Rachael L. , Lew Kok Keong , VanMil Brenda L. , Stahlbush Robert E. , Liu Kendrick X. , Caldwell Joshua D. , Klein Paul B. , Wu Ping , Fatemi Mohammad , Eddy Charles R. , Gaskill D. Kurt
Published: March 2009

X-ray diffraction (XRD) rocking curves were mapped across 4H-SiC, 3-inch, 8° off-cut
substrates prior to and after epitaxial growth, where a pattern of slightly higher defectivity region
was clearly seen. This same pattern was apparent in both cross-polarization images of the epiwafers
and microwave photoconductivity decay (μ-PCD) lifetime maps of the epilayers, where the latter
shows the lifetime in the high defectivity regions had drastically decreased. Within the short
lifetime regions, electron trap concentrations were similar to that as in the long lifetime regions as
determined by deep level transient spectroscopy; however, the extended defect density was
significantly higher. Consequently, high spatial resolution XRD can be a valuable tool in preselecting
substrates for epitaxial growth to produce low defect density material with long injected
carrier lifetimes.
Variations in the Measured Carrier Lifetimes of n- 4H-SiC Epilayers
Authors: Klein Paul B. , Caldwell Joshua D. , Shrivastava Amitesh , Sudarshan Tangali S.
Published: March 2009

The effects of measurement technique and measurement conditions (injection level,
temperature) on the measured carrier lifetimes in n- 4H-SiC epilayers are investigated. For three
optical measurement techniques, it is shown that the high and low injection lifetimes can vary
dramatically. Differences in the lifetime for varying injection level and temperature are approached
both experimentally and via carrier dynamics simulations, assuming Z1/Z2 as the dominant defect.
Reasonable agreement between measured and calculated behavior is obtained, as is insight into the
recombination kinetics associated with the lifetime limiting defect.
Characterization of Electrical Properties in SiC Crystals by Raman Scattering Spectroscopy
Authors: Kitamura T. , Nakashima Shinichi , Kato Tomohisa , Kojima K. , Okumura Hajime
Published: March 2009

We characterized the 4H- and 6H-SiC bulk crystals with graded doping and epitaxial films
with various carrier densities by Raman scattering spectroscopy. Electrical properties such as free
carrier density were examined for the SiC crystals through Raman measurements of the A1
LO-phonon plasmon coupled (LOPC) mode and its line shape analysis. The peak frequency and band
width of LOPC mode varied with carrier density in the range from 1016 to 1019 cm-3. The line shape
analysis revealed that the carrier density in the SiC crystals can be simply estimated from measured
frequency shift of LOPC mode for 4H- and 6H-SiC crystals.
Characterization of Electronic Properties of Different SiC Polytypes by All-Optical Means
Authors: Neimontas K. , Jarašiūnas Kęstutis , Yakimova Rositza , Syväjärvi Mikael , Ferro Gabriel
Published: March 2009

We applied a picosecond transient grating technique for studies of nonequilibrium carrier
dynamics in differently grown or doped SiC polytypes. Optical carrier injection in 4H-SiC at two
different wavelengths (266 and 355 nm) allowed us to vary the depth of the photoexcited region and
determine photoelectric parameters of high density (from ~1016 to ~1019 cm-3) carrier plasma in the
temperature range 10 – 300 K. A strong decrease of carrier lifetime with increasing nonequlibrium
carrier density was found in 4H-SiC samples at 300 K and fitted by bimolecular recombination with
coefficient B = 3 × 10-11 cm3 s-1. In 3C-SiC epilayers, the opposite tendency was observed over a wide
temperature range and attributed to recharging of defect states.
Computational Analysis of SiC HTCVD from Silicon Tetrachloride and Propane
Authors: Makarov Yuri , Talalaev R.A. , Vorob'ev A.N. , Ramm Mark S. , Bogdanov Maxim V.
Published: March 2009

This work focuses on computational analysis of SiC High Temperature Chemical Vapor Deposition (HTCVD) from silicon tetrachloride (SiCl4) and propane (C3H8) precursors supplied separately and diluted by argon and hydrogen, respectively. It is aimed at verification of the technological parameters providing complete precursor decomposition in the growth chamber, the optimal gas composition for SiC growth, and the required silicon-to-carbon ratio in the wafer region, as well as suppression of parasitic deposits at the reactor walls and inlet unit via the optimization of the reactor geometry and temperature distributions. As a result, a high growth rate and maximal yield are expected to be achieved due to minimal precursor losses.
Space Charge Waves in 6H-SiC and 4H-SiC
Authors: Lebedev Alexander A. , Lemmer M. , Hilling B. , Wohlecke M. , Imlau Mirco , Bryksin V.V. , Petrov M.
Published: March 2009

Resonant excitation of space charge waves (SCW) by means of an oscillating light
pattern has been investigated in hexagonal silicon carbide with 4H and 6H stacking sequence. The
experimental data can be explained by the existence of trap recharging waves in the 4H-SiC sample
and damped forced charge-density waves in the 6H-SiC sample.
Mapping of Defects in Large-Area Silicon Carbide Wafers via Photoluminescence and its Correlation with Synchrotron White Beam X-Ray Topography
Authors: Chen Yi , Balaji R. , Dudley Michael , Murthy Madhu , Maximenko Serguei I. , Freitas Jaime A.
Published: March 2009

Comparative studies of defect microstructure in 4H-SiC wafers have been carried out
using photoluminescence (PL) imaging and grazing-incidence Synchrotron White Beam X-ray
Topography. Images of low angle grain boundaries on the PL images correlate well with SWBXT
observations, and similar correlation can be established for some micropipe images although the
latter is complicated by the overall level of distortion and misorientation associated with the low
angle grain boundaries and the fact that many of the micropipes are located in or close to the
boundaries. This validation indicates that PL imaging may provide a rapid way of imaging such
defect structures in large-scale SiC wafers.
Contactless Topographic Analysis of Locally Inhomogeneous Resistivity in SiC and Cd(Zn)Te
Authors: Mueller Stefan , Stibal Rudolf , Jantz Wolfgang
Published: March 2009

Contactless topographic resistivity mapping is used to characterize SiC and Cd(Zn)Te wafer
material. For locally inhomogeneous material, detailed analysis of the deformed charge transients
allows the evaluation of the partial resistivity contributions.