bluuebunny/crossref_metadata_2025 huggingface dataset:
Epitaxial Growth of TiN(100) on Si(100) by Reactive Magnetron Sputtering at Low Temperature
Authors: Sheu Wei-Hwa , Wu Shinn-Tyan
Published: October 2002

Epitaxial growth of TiN (150 nm) on Si(100) has been thoroughly
investigated by X-ray pole figure analysis. During reactive magnetron
sputtering using metal targets, the epitaxial ordering of sputtered
atoms starts between 300°C and 400°C. Below this range, the films have a
fiber structure, with TiN(200) parallel to Si(100). Above this
range, further in-plane order is developed such that Si(001)[110]//TiN(002)[110],
which is clearly established by both X-ray
and electron diffractions. This is the case despite the large lattice
mismatch (Δa/a=24.6%), suggesting that lattice matching is not
always a prerequisite for epitaxial growth.
Characterization of ZnSe/GaAs(001) Heteroepitaxial Interfaces by X-Ray Reflectivity Measurement
Authors: Takase Aya , Kuribayashi Masaru , Ishida Kohtaro , Kimura Kozo , Kuo Li-Hsin , Yasuda Tetsuji , Miwa Shiro , Yao Takafumi , Tomita Hirofumi , Komiya Satoshi
Published: October 2002

The interfacial structure of ZnSe/GaAs(001) epitaxial crystals is studied using X-ray reflectivity measurements. The samples are grown by molecular beam epitaxy (MBE)
with Se- or Zn-treatment. To obtain clear oscillation profiles of reflectivity, the measurements are carried out using synchrotron radiation near the Se K absorption edge and at a distance from it. Comparing
observed curves with curves calculated using Parratt's theory, the thicknesses and the electron densities of the transition layers of ZnSe/GaAs are determined. The
thicknesses and the electron densities compared with epitaxial ZnSe are one molecular layer (1 ML) and 82% for the Zn-treated sample, 3 MLs and 80% for the Se-treated sample, respectively.
Fine-Grained SrBi2Ta2O9 Thin Films by Low Temperature Annealing
Authors: Ogata Nobuhito , Nagata Masaya , Ishihara Kazuya , Urashima Hitoshi , Okutoh Akira , Yamazaki Shinobu , Mitarai Shun , Kudo Jun
Published: October 2002

A new low pressure annealing method for preparation of SrBi2Ta2O9 thin films is proposed.
These thin films were prepared on Pt/TiO2/SiO2/Si substrates by the metalorganic decomposition
(MOD) method, and their structural and electrical properties were investigated. Low pressure
annealing was performed at 650°C for 60 min in a 2 Torr oxygen ambient per coating. The films
were well crystallized and exhibited fine-grained and dense structures with grain size of about 50 nm. P
r=4.9 µC/cm2, E
c=24 kV/cm, I
L=8.6×10-8 A/cm2 at a applied voltage of 3 V and breakdown
voltage (V
B) of over 20 V were obtained for the 200-nm-thick films. Futhermore, in the 100-nm-thick SBT film, a saturation voltage of 1 V was obtained. P
r=3.6 µC/cm2, E
c=25 kV/cm, I
L=5.5×10-8 A/cm2 at 1 V and V
B was over 10 V. Therefore, this method is very useful for highly
integrated ferroelectric nonvolatile memory application.
Polarized Optical Heterodyne Profilometer
Authors: Huang Yeu-Chuen , Chou Chien , Chou Ling-Yu , Shyu Jenn-Chyang , Ming Chang Ming Chang
Published: October 2002

A quasi common path polarized optical heterodyne interferometer with an aluminum coated polarized beam splitter is proposed in order to sense the surface profile. The heterodyned P wave is generated by two acousto-optic modulated P waves with different frequencies in the Mach-Zehnder interferometer. So is the heterodyned S wave. Both heterodyned P wave and S wave propagate through quasi common optical path in the interferometer. An aluminum coated polarized beam splitter was used to conduct a quasi common path configuration to sense the surface profile. The stability of the interferometer was ±0.25°/0.5 h and 0.5% in phase and amplitude respectively. The height sensitivity was 2 Å and the lateral resolution was 2 µ m in the experiment. In case of a birefringence lens or a Wollaston prism is suggested to replace the aluminum coated polarized beam splitter, a novel polarized common path profilometer with better stability is expected.
Experimental Study on Heat Flux from an Argon RF Plasma Using Laser Interferometry Method
Authors: Takaki Koichi , Takahashi Atsushi , Fujiwara Tamiya
Published: October 2002

The plasma heat flow to a birefringent substrate (LiNbO3) in an argon rf
discharge has been investigated with the help of a laser interferometry method.
This method is based on monitoring the variation of natural birefringence with
temperature by the interferometry. The evaluation of the temperature curve shows
that heat flux from the plasma towards the substrate depends on which electrode
the substrate is put on. While the value is about 8% of the applied power in
the case of the substrate on the powered electrode, the heat flux decreases to
less than 1% in the case of on the grounded electrode. Ion fluxes have been
obtained from the measured values of plasma potential, electron density and
electron temperature. In the case of low pressure the ion flux approximately
agrees with the value of the heat flux. However it decreases with an increase
in pressure, and is almost 35% of the heat flux at 200 mTorr. Gas temperature
in the plasma has been measured using a thermocouple in order to investigate
the influence of gas pressure on the heat flux by neutral particles. The result
shows that the gas temperature increases by raising the gas pressure.
Coma Aberration Measurement by Relative Shift of Displacement with Pattern Dependence
Authors: Sato Takashi , Nomura Hiroshi
Published: October 2002

In lithography for LSI pattern exposure, pattern displacement was caused by
aberrations of the projection lens. This displacement depended on the pattern position
as well as the pattern size. Relative pattern shifts of the pattern to a 2.0 µm isolated
pattern were measured using submicron bars-in-bars marks, which are similar to the
overlay measurement marks. The measurement marks lie on the same mask and are
exposed at the same time by a KrF excimer stepper with a numerical aperture (NA) of
0.6 and wavelength of 248 nm. The relative pattern shift showed that the lens had
magnification errors which depended on the pattern size. Coma aberration was
presumed from the measurement results of aerial image simulation. The coma was
expressed in terms of Seidel aberrations. Wave aberration from the simulation
corresponded with the measurement results for the two types of illuminations, i.e., such
as a standard circuler source and an annular source.
Direct Determination of Azimuth Angles in Photoelastic Modulator System
Authors: Chao Yu-Faye , Wang Charn-Kuo
Published: October 2002

Instead of the nulling method, a high-level intensity technique is
proposed to determine the relative azimuth orientation of a photoelastic
modulator and an analyzer. In a photoelastic modulating system, one
can obtain a DC intensity distribution by varying the phase modulation
amplitude at two azimuth angles of the analyzer, which are π/4 apart
from each other. The relative azimuth orientation can be determined
by taking the ratio of the slopes of these two intensity distributions
around the linear region of the zero point of the zero-order Bessel
function. A similar technique is also applicable to wave plates for
aligning their optical axes with the system.
Electron Beam Damage in the SiN Membrane of an X-Ray Lithography Mask
Authors: Choi Sang-Soo , Kim Jong-Soo , Chung Hai Bin , Yoo Hyung Joun , Kim Bo Woo
Published: October 2002

The damage caused as a result of exposure to an electron beam of 20 to 50 kV acceleration voltage on the SiN membrane of an X-ray mask has been investigated. It determined that the optical and the mechanical properties of this material are modified and may potentially limit its use as a membrane in an X-ray mask structure for high density memory devices of giga bit dynamic random access memory (DRAM) level. In particular, after exposure to the electron beam of a 50 kV acceleration voltage and a dosage of 900 µC/cm2, the optical transmission of the SiN membrane fell by about 17% in the wavelength of 633 nm and the change of the out of plane distortion(OPD) on the 16 ×16 mm2membrane was observed. The difference in the mechanical deflection before and after exposure to the electron beam of 20 kV to 50 kV acceleration voltage on the membrane area of 800 ×800 µm2was about 500 Å to 200 Å which was measured by the α-step (Tencor 200) with the stylus force of 19.6 dyn.
Solvent Effect on Domain Formation of 4-Mercaptopyridine Self-Assembled Monolayers on Au(111) Substrate by Scanning Tunneling Microscopy
Authors: Umemura Kazuo , Fujita Katsuhiko , Ishida Takao , Hara Masahiko , Sasabe Hiroyuki , Knoll Wolfgang
Published: October 2002

We have studied the growth process of 4-mercaptopyridine (4-PySH)
self-assembled monolayers (SAMs) on Au(111) substrate, by scanning
tunneling microscopy (STM). The three factors which were investigated for
the domain formation of 4-PySH were; solvent effect, immersion time
dependence and the impurity effect. STM imaging revealed that the solvent
effect was very significant in determining the surface morphology of the 4-PySH
SAM growth, which was not observed on X-ray photoelectron spectra
(XPS). These results indicated that the solvent was an important factor in the
domain formation process, especially ethanol which as a typical SAM solvent,
assisted the reconstruction of 4-PySH domains on the substrate.
χ(2) Solitary Waves in Graded-Index Slab Waveguides
Authors: Franco Nalesso Barbara Costantini , Giacomo Someda Carlo
Published: October 2002

Analytical approximate stationary solutions of solitary waves
in a graded-index slab waveguide, are found for Type I second harmonic
generation (SHG) processes, ignoring the usual
assumptions that the linear and nonlinear effects occur separately
in each transverse direction.
We compare our results with those available
in the literature and show how our model
can depict accurately the influence
of the nonlinearity on the phase constant.
The analytical results are also validated by the
numerical integration of the governing equations.
Characteristics of Ceramic Microheater for Fiber Coupler Fabrication
Authors: Takeuchi Yoshiaki , Hirayama Mamoru , Sumida Shin , Kobayashi Osamu
Published: October 2002

Properties of a microheater have been greatly improved for use in fused-tapered fiber coupler
fabrication by employing a ceramic heat source. Lanthanum chromite was adopted as a heat source
because it has the highest melting point for the use in air and can be used without cooling equipment.
The usual susceptibility to heat shock exhibited by ceramic heaters was essentially overcome by
miniaturizing the structure so that it could handle quick temperature changes during fiber coupler
fabrication. The microheater was typically only 22 mm long which helps shorten the fiber coupler
length. The lifetime of the microheater was about 1500 h at 1530°C. This is more than 100 times that
of the previously developed precious metal microheater. There was only a slight change in the
temperature distribution along the heater with heating time. 1.31/1.55-µm wavelength-division-multiplexing (WDM) couplers were fabricated during the lifetime test and it was confirmed that the
coupling properties could be very well controlled even after the test.
An Optical Network Unit (ONU) Chip Based on Stacked Planar Optics
Authors: Mizuno Rogerio Jun , Kato Toshio , Aoki Yasuhiko , Iga Kenichi
Published: October 2002

In this paper, an optical network unit (ONU) based on stacked planar optics is described.
The ONU chip consists of planar microlens (PML) arrays and dielectric multilayered filters
conveniently arranged to perform a wavelength division multiplexing (WDM)
transmitter/receiver function. To avoid polarization dependence, nonpolarizing filters were
designed for WDM filters, half-mirrors and mirrors. An insertion loss of less than 2.5 dB and a
polarization-dependent loss (PDL) of less than 0.5 dB were obtained for the 1.3 µm port.
Crosstalk was estimated to be as low as -26 dB. For the 1.55 µm port, both insertion loss and
PDL of less than 0.08 dB were obtained.
Design and Performance of LiNbO 3 Optical Modulator with a Superconducting Electrode
Authors: Kanda Yutaka , Yoshida Keiji , Uezono Itaru
Published: October 2002

The performance of a LiNbO3 optical modulator with a superconducting electrode as the
transmission line of a traveling-wave signal has been studied theoretically as well as
experimentally. In the case of velocity matching between signal and optical waves using a
shielding plane on top of a coplanar waveguide, numerical calculations of the attenuation
constants of both superconducting and normal-conducting transmission lines indicate that the
performance of the optical modulator is far superior to that using normal metals with respect to
the figure of merit of bandwidth/driving voltage. Microwave characteristics of a traveling-wave-type LiNbO3 optical modulator with a superconducting electrode (Nb) have been also studied
experimentally in the temperature range from 300 K to 4.2 K. In the frequency range between
dc and 26.5 GHz, it is shown that the obtained modulation depth is in good agreement with the
theoretically expected one. The present results demonstrate the possible applications of
superconducting electrodes to high-performance LiNbO3 optical modulators.
A Cavity-SNOM (Scanning Near-field Optical Microscopy) Head Using a Laser Diode
Authors: Ito Kenchi , Shintani Toshimichi , Hosaka Sumio , Muranishi Masaru
Published: October 2002

A cavity-SNOM (scanning near-field optical microscope) head using a laser diode is proposed and
studied theoretically and experimentally. Theoretically, we study the optical properties using
conventional rate equations. Several conditions to detect the SNOM signal with a photodiode are
discussed. Experimentally, the dependence of output power of the laser diode on the injection current
is measured. A sufficiently strong modulation signal is detected using a tapered fiber as the probe, but
no modulation signal is detected using a tapered fiber with a small aperture (SNOM probe). The
conditions for detecting a signal using a SNOM probe are also discussed, and we suggest that a laser
diode with a SNOM probe fabricated on its facet is essential for realizing a practical cavity-SNOM head.
Observation of Silicon Surfaces Using Ultrahigh Vacuum Noncontact Atomic Force Microscope
Authors: Kitamura Shin'ichi , Suzuki Katsuyuki , Iwatsuki Masashi
Published: October 2002

The advantage of noncontact atomic force microscope (NC-AFM) is, that the interaction between the tip and the sample is reduced as compared with the other AFM techniques. Furthermore, in the ultrahigh vacuum (UHV) NC-AFM, the atomic resolution images can be obtained, as the capillary forces between the cantilever tip and the sample are eliminated. A UHV NC-AFM with a unique frequency modulation (FM) technique has been developed. We have obtained atomic resolution images of the Si(111) 7×7, Si(100) 2×1 structures and oxygen adsorption Si(111)7×7 surface along with the scanning tunneling microscope (STM) images. Using a similar technology, a UHV scanning Kelvin probe microscope (SKPM) utilizing the gradient of electrostatic force has also been developed. In the SKPM it is possible to simultaneously observe the contact potential difference (CPD) and the NC-AFM topographic images. The CPD image of Si(111) surface with deposited Au clearly shows the potential difference between the 7×7 and the 5×2 phases. A high resolution image of the Ag-deposited Si(111)7×7 surface is obtained by simultaneous observation of the CPD and the NC-AFM topographic images.
Local Tunneling Barrier Height on Si(111) Reconstructed Surfaces
Authors: Miyao Nobuhiro Horiguchi
Published: October 2002

We observed local tunneling barrier height images on reconstructed Si(111) surfaces. Local tunneling barrier height on √3×√3 reconstructed structure was almost the same as that of 7×7 structure. In contrast, local tunneling barrier height on the c(4×2) reconstructed structure was lower than that on the 7×7 structure. Both reconstructed structures were induced by transition metal atom adsorption. This is influence of three-dimensional spatial distribution of surface wave function. We also found that local tunneling barrier height on the ring cluster structure was lower than that on 7×7 structure.
Scanning Tunneling Microscopy Study of Fe Submonolayer Film on Vicinal Au(001)
Authors: Takeshi Kawagoe Takeshi Kawagoe , Kousuke Sogabe Kousuke Sogabe , Nobuhiro Kondoh Nobuhiro Kondoh , Ryu Narusawa Ryu Narusawa , Akiyoshi Itoh Akiyoshi Itoh
Published: October 2002

The initial stage of the growth process of Fe submonolayer films
on a vicinal Au(001) surface was studied by
means of a scanning tunneling microscope.
The vicinal Au(001) surface was characterized by an average terrace width of
20 nm, separated by straight, monoatomic steps aligned along
the [110] or [110] direction.
The correlation between the formation of steps and the reconstructed
structure is discussed.
One-dimension-like Fe structures with 4 nm width and 0.5 nm height
have been grown by decoration of monoatomic steps of Au(100) surface.
Ballistic-Electron-Emission Microscopy on Epitaxial Silicides
Authors: Känel Hans von , Meyer Thomas , Klemenc Michaela
Published: October 2002

Ballistic-electron-emission microscopy (BEEM) and
spectroscopy (BEES) applied to epitaxial CoSi2/Si interfaces are reviewed.
Interfacial dislocations in 2–3-nm-thick CoSi2(001)/Si(001)
films with Burgers vector
b=a/4<111>
lower the barrier height by almost 0.1 eV at 77 K.
This corresponds to a
decrease in the Schottky barrier height ΦB at the metallurgical
interface from ΦB=0.74±0.03 eV, characteristic of defect-free
regions, to near zero within the range of the strain field of a few
nanometers. In contrast, the dislocations of type
b=a/6<112>
present at CoSi2/Si(111) interfaces do not affect
the barrier height. CoSi2/Si(111) films are more suitable for studying
interfacial scattering by BEEM than CoSi2/Si(100) films, because of their
simpler surface structure and because of band structure effects.
Here, individual point defects can be
resolved. Their spatial distribution indicates diffusion along the interface
during film growth. By analysing the shape of BEES spectra obtained on
isolated point defects, and by making use of the projected band structure
predicting the BEES current to set in ∼0.2 eV above the Schottky
barrier, it may be concluded that the defects are located at the interface.
Biological Cryo-Atomic Force Microscopy: Instrumentation and Applications
Authors: Sheng Sitong , Shao Zhifeng
Published: October 2002

Although atomic force microscopy (AFM) has been successfully applied to a number of biological specimens under aqueous solution, its resolving power has been
limited due to specimen deformation or damage induced by the scanning tip, especially with large flexible and heterogeneous specimens. To further expand the capabilities
of the AFM, a cryo-AFM was recently developed to operate under ambient pressure in liquid nitrogen vapor. The operating principle of this novel system is discussed, and some of the most recent applications
of the cryo-AFM to various biological specimens are reviewed. These results have clearly demonstrated the power of the cryo-AFM in the study of biological structures,
and at the same time, have revealed novel structural information of several important molecules.
Comparative Atomic Force and Scanning Electron Microscopy for Fine Structural Images of Nerve Cells
Authors: Takuro Tojima Takuro Tojima , Dai Hatakeyama Dai Hatakeyama , Yukako Yamane Yukako Yamane , Kazushige Kawabata Kazushige Kawabata , Tatsuo Ushiki Tatsuo Ushiki , Shigeaki Ogura Shigeaki Ogura , Kazuhiro Abe Kazuhiro Abe , Etsuro Ito Etsuro Ito
Published: October 2002

Although we can routinely obtain fine structural images of cells by atomic force microscopy (AFM), the adequacy and reliability of morphological information acquired from these AFM images remain to be examined. In this report, we compared images of the fine structures of nerve cells as observed by both AFM and scanning electron microscopy (SEM). Although AFM revealed the structure of the top views of cells in greater detail than SEM, their side structures were better observed by SEM. The linear structures in the neural processes detected only by AFM were confirmed, by immunofluorescence staining, to be reflections of the cytoskeletal structures located beneath the cell membrane. These differences between the AFM and the SEM images reflected the characteristics of the detection systems and methods used for sample preparation. Therefore, these results revealed that more detailed information on cell morphology can be obtained by using both AFM and SEM to advantage.
Imaging Elastic Properties of Soft Materials Immersed in Water Using Force Modulation Mode in Atomic Force Microscopy
Authors: Hisashi Haga Hisashi Haga , Shigeo Sasaki Shigeo Sasaki , Mayumi Morimoto Mayumi Morimoto , Kazushige Kawabata Kazushige Kawabata , Etsuro Ito Etsuro Ito , Kazuhiro Abe Kazuhiro Abe , Takashi Sambongi Takashi Sambongi
Published: October 2002

Using the force modulation mode in atomic force microscopy (AFM),
we have succeeded in imaging elastic properties of agar gels immersed in
water.
The elastic images of agar have been captured simultaneously with
the topographic images.
Stiffer grains of agar whose size is about 200 nm can be clearly
seen in the elastic image of 3.0% agar, while they are not so visible
in the case of 1.5% agar.
These grains probably correspond to aggregation of agar which
cannot be observed in the topographic images.
We also measured force-versus-distance curves using AFM
to confirm that the absolute values of elastic modulus (Young's
modulus) of agar coincide with the bulk values measured using the
conventional stress-strain method.
The estimated values of the elastic moduli with the AFM were 40 and
90 kPa for 1.5% and 3.0% agar gels, respectively.
These are in good agreement with the respective bulk values of 30
and 80 kPa obtained using the conventional method.
Smoothing of Si Trench Sidewall Surface by Chemical Dry Etching and Sacrificial Oxidation
Authors: Yahata Akihiro , Urano Satoshi , Inoue Tomoki , Shinohe Takashi
Published: October 2002

By combining the effects of chemical dry etching (CDE) and sacrificial
oxidation, a smooth trench sidewall surface with a root-mean-square (Rms)
roughness of less than 1 nm was obtained. The possibility of obtaining a
smooth surface such as that of a planar metal-oxide-semiconductor (MOS) by
increasing both the CDE etching time and the oxide thickness of sacrificial
oxidation appears likely.
Effects of H2O Absorption on Electrical Property and Crystal Structure in YBa2Cu3Ox
Authors: Edo Shoichi , Takama Toshihiko
Published: October 2002

Polycrystals of YBa2Cu3O
x
(x=6.09, 6.24, 6.4, 6.52, 6.71 and
6.95) were annealed in air. The specimens with x≧6.4 were
transformed from the superconducting to normal conducting phase
at annealing temperatures between 100 and 200°C. The powder
X-ray diffraction profiles revealed that the original
orthorhombic phase disappears and a new phase with a long
lattice spacing grows at the above temperatures. Annealing
tests carried out in several kinds of atmospheres clarified
that the changes in resistivity and in crystal structure are
induced by the absorption of H2O molecules in air by means of a
diffusion process.
Fast Three-Dimensional Computation of the Optical Propagation Equation Using a Desktop Personal Computer
Authors: Bontoux Thierry , Kato Yoshinori , Nakatsuka Masahiro
Published: October 2002

We developed a method of computing the three-dimensional (3D) solution of the
optical propagation equation using no approximation other than its picosecond pulse
expression. The algorithm is fast enough to run on a personal computer (PC) with usual
delays of 1 or 2 min for calculation. Some results are given to emphasize precision
problems, but most of the time the high stability of the algorithm allows large calculation
steps, up to 1 cm in some cases.
Influence of Native Oxides on the Reliability of Ultrathin Gate Oxide
Authors: Takeda Mikako , Ohwaki Takeshi , Fujii Hideo , Kusumoto Eisuke , Kaihara Yoshiyuki , Takai Yoshizo , Shimizu Ryuichi
Published: October 2002

The influence of wet cleaning processes, such as the SC-1 and H2O2 processes, on the time dependent dielectric breakdown (TDDB) of ultrathin gate oxide was investigated. A large difference in the reliability by wet cleaning processes was observed, especially when an electrode is an anode. The reliability of the gate oxide by the H2O2 process was worse than SC-1. It was found by Fourier transformed infrared attenuated total reflection (FT-IR-ATR) analysis that the amount of structural imperfection of native oxides formed in H2O2 was larger than SC-1. Since stress-induced positive charges which affect the TDDB properties are generated near the anode- side oxide interface, a large amount of structural imperfection in the native oxides formed in H2O2 probably results in a defective thermal oxide surface, leading to an increase in the generation and trapping of positive charge.
The Influence of Surface Reflectivities on Measurement of the Torsional Anchoring Strength of Nematic Liquid Crystals
Authors: Yang Fuzi , Sambles John Roy
Published: October 2002

The polarisation dependent normal incidence transmissivity of a multilayered system
encompassing within it an optically uniaxial layer has been analysed in detail using
multilayer optics modelling. It is shown that even for this simple case of normal incidence
the orientation of the uniaxial sample and two polarisers needed to give a transmission
minimum is significantly influenced by the optical phase shifts caused by reflections at the
isotropic boundary layers. We highlight the failure of the simplified approach to this
problem which uses the Jones matrix, ignoring multiple reflections within the system.
Consequently we show that the standard technique of quantifying the boundary twist
offset angles by determining with polarisers the minimum points in the normal incidence
transmission for a thin nematic liquid crystal cell may well lead to seriously wrong values
for the torsional anchoring strength of aligning surfaces.
Etching Effect of Hydrogen Plasma on Electron Cyclotron Resonance-Chemical Vapor Deposition and Its Application to Low Temperature Si Selective Epitaxial Growth
Authors: Kimihiro Sasaki Kimihiro Sasaki , Toshiaki Takada Toshiaki Takada
Published: October 2002

Si etching properties by H2 plasma generated using the ECR technique were investigated. The etch rate increases in the order of (111) < (110) < (100). This phenomenon is explained by the bond formation of the Si atoms and the number of the atomic layer for each orientation. Si epitaxial growth was examined by the ECR plasma CVD technique using a SiH4–H2 gas system. At the substrate temperature of 150°C, although the crystallinity degrades with an increase of the film thickness, we confirmed epitaxial growth. An appropriate etching process with H2 plasma, which enhances rearrangement of the Si atoms, is important for Si epitaxial growth at low temperatures. Si epitaxial films with excellent crystallinity and smooth surface morphology as determined by observation of the Kikuchi-lines were obtained at 450°C. Complete selective epitaxial growth was successfully realized at substrate temperature of 150°C by utilizing the etch rate difference for the crystallinity of deposited films. However, the epitaxial thickness was limited to approximately 40 nm. For the substrate temperatures higher than 150°C, the film polycrystallization on an SiO2 substrate degraded the selectivity.
Study of Deep Levels in Mesa-Type HgCdTe Device
Authors: Yoshino Junya , Morimoto Jun , Wada Hideo
Published: October 2002

The deep levels in the p+-on-n mesa-type Hg1-x
Cd
x
Te (x=0.222) device fabricated on the Si
substrate by the molecular beam epitaxy method have been studied using the isothermal capacitance
transient spectroscopy (ICTS) method and the spectral analysis of deep level transient spectroscopy
(SADLTS) method. The value of the activation energy and the capture cross section could not be
determined by means of ICTS because the apparent peaks were not obtained in the ICTS spectrum.
However, five deep levels have been confirmed by SADLTS and the activation energies and the
capture cross sections for each level were calculated. The confirmed levels existed from 19.7 meV
to 45.7 meV below the conduction band edge. Three deeper levels are considered to be related to
the Hg vacancy, whereas two shallower levels are considered to be related to the impurity in the
n-type region. Moreover it is suggested that three deeper levels may assist the tunneling current in
the reverse bias region. On the other hand, the obtained values of the capture cross sections ranged
from 10-18 to 10-11 cm2.
Temperature Dependence of the Emittance of LiF and LiNbO3 in the Near-Infrared Spectra
Authors: Chen Jyh-Chen , Hu Chieh , Lee Yeou-Chang
Published: October 2002

This study investigates the temperature dependence of the normal emittance in 3–5, 5,
10.6 and 8–12 µm spectral range for LiNbO3 and LiF rods with both crystal and
polycrystalline structures. According to the results, the normal emittance in the near-infrared
spectra increases with increasing wavelength. The normal emittances at
10.6 and 8–12 µm are not only invariant with temperature, but also exceed 0.9.
When the temperature increases, the normal emittances at 3–5 and 5 µm for the LiF
single-crystal rod continuously increase regardless of the phase change from the solid
state to the liquid state. Before the temperature reaches the Curie point, the normal
emittances at 3–5 and 5 µm for the LiNbO3 single-crystal rod increase with increasing
temperature. The normal emittances at 3–5 and 5 µm then decrease as the
temperature further increases. A significant decrease in the normal emittance at 3–5
and 5 µm occurs when the emission is only from the melt. In addition, the
magnitudes of the normal emittance at 3–5 and 5 µm are enhanced by the scattering
effect due to the porous structure of the solid.
Theoretical Studies of Element-Specific Kikuchi-Band Effects in X-Ray Photoelectron Diffraction
Authors: Omori Shinji , Nihei Yoshimasa
Published: October 2002

A violation of the extinction rule for Bragg reflection has been recently observed as the
anomalous extinction of Kikuchi bands with nonzero structure factors in the X-ray photoelectron
diffraction pattern of F1s emission from a CaF2(111) surface. To explain this violation, we derived the
Kikuchi-band intensity formula and found that this formula leads to a novel extinction rule of Kikuchi
bands. In addition, on the basis of the formula, we set up a scheme of element-specific Kikuchi-band
analysis for determining structure factors.
Strain Effect on Electronic States of Si near a Si/NiSi2Interface Measured by Electron Nanoprobe Techniques
Authors: Yutaka Wakayama Yutaka Wakayama , Shun-ichiro Tanaka Shun-ichiro Tanaka
Published: October 2002

Lattice strains near the Si/NiSi2interface and their effects on electron energy-levels of Si were investigated via experimental and theoretical approaches. For highly spatially resolved analysis, electron nanoprobe techniques were employed: convergent beam electron diffraction (CBED) for lattice strain and electron energy-loss spectroscopy (EELS) for the electron energy-levels. Additionally, a theoretical analysis based on the density-functional theory (DFT) was performed to explain the experimental results. The actual distribution of the lattice strains was complicated; both tensile and compressive strains were found to coexist near the interface. Shifts in the SiL23-edge of the EEL spectra were found to be induced by the lattice strain. Finally, we described the “distribution of the electron energy-levels” as the strain distribution around the interface in a submicron region.
Effect of CdTe Layer Thickness on Hg1-xCdxTe Epilayer Growth by Isothermal Vapor Phase Epitaxy Using (100) CdTe/GaAs Substrates and Void Formation at the Interface
Authors: Koo Bonheun , Wang Jifeng , Ishikawa Yukio , Isshiki Minoru
Published: October 2002

The growth of Hg1-x
Cd
x
Te (MCT) epilayers by isothermal vapor phase epitaxy
(ISOVPE) on (100) CdTe/GaAs substrates, with various thicknesses of CdTe layers, is
reported. Subsequent to ISOVPE growth of MCT layer, we observed the formation of
triangular voids at the interface between CdTe and GaAs, which strongly depends on the
thickness of the CdTe substrate layers. The problem of void formation and Ga
outdiffusion can be overcome by using a sufficiently thick CdTe layer. Although the
crystallinity of CdTe layers grown on GaAs by hot wall epitaxy (HWE) is strongly
related to thickness, the quality of MCT epilayers is better than that of the substrate layer
and is independent of the quality of CdTe layers. This result is attributed to the growth
mechanism of ISOVPE being different from other epitaxial methods.
Thermally Activated Motion of a Screw Dislocation Overcoming the Peierls Potential for Prismatic Slip in an hcp Lattice
Authors: Edagawa Keiichi , Suzuki Takayoshi , Takeuchi Shin
Published: October 2002

The prismatic slip in hcp metals has been studied by calculating the thermally
activated motion of a 1/3[1120] screw dislocation in a two-dimensional Peierls
potential assumed in the (1120) plane. The kink pair formation process for the
transition of the dislocation from a stable position to another under applied stress has
been investigated and the activation energies for the two types of transitions
constituting the prismatic slip have been calculated. Using the activation energies, the
critical flow stress τc has been deduced as a function of the direction of the applied
stress χ and temperature. The calculated τc–χ relations deviate significantly from
the Schmid law and well reproduce the deviation relation observed in the experimental
data of Ti. The deviation from the Schmid law originates in a structural feature of the
hcp lattice itself, i.e., a zigzag arrangement along the prismatic plane of atomic rows.
Heteroepitaxy of Layered Compound InSe and InSe/GaSe onto GaAs Substrates
Authors: Budiman Maman , Yamada Akira , Konagai Makoto
Published: October 2002

The van der Waals epitaxy of InSe films was performed on (111)GaAs surface at the
growth temperature of 350°C. A spiral trigonal structure was observed on the surface of the
InSe films. To improve crystal quality of the InSe films, their orientation control was
investigated. The growth rate decreased rapidly as the growth temperature increased and no
InSe films were obtained at growth temperatures higher than 480°C. At growth temperatures
of 450°C and higher, a double-domain structure was observed, probably due to the
coexistence of In4Se3 phase in the films. Therefore, the InSe film was directly grown on c-axis
inclined GaSe, and it was revealed that InSe films were more easily grown on GaSe than on
(001)GaAs surface, due to the same crystal structure. Furthermore, for fabrication of the
quantum well structure, heteroepitaxial growth of GaSe/InSe/GaSe films on (001)GaAs
substrate was investigated.
Reflectance Difference Spectra Calculations of GaAs(001) As- and Ga-rich Reconstruction Surface Structures
Authors: Misao Murayama Misao Murayama , Kenji Shiraishi Kenji Shiraishi , Takashi Nakayama Takashi Nakayama
Published: October 2002

The reflectance difference (RD) spectra of nine GaAs(001) surface
reconstructions, (2×4)β2, (2×4)α,
(2×4)γ2, (2×4)β1, (2×4)γ1 and
c(4×4) reconstructions on As-rich surface and
(4×2)β2, (4×2)α
and (4×2)β1 reconstructions on Ga-rich surface,
were studied by using the nearest-neighbor s
p
3
s
*
tight-binding method.
The surface atomic positions and the tight-binding interaction
parameters were
obtained by the ab inito pseudopotential calculations.
We found that the RD spectra have considerably different features
between As- and Ga-rich surface reconstructions.
The RD spectra of As-rich surfaces
are mainly understood
by transitions between top As-dimer states,
while the RD spectra of Ga-rich surfaces
are explained by the surface electronic states
resulting from the sinkage of surface Ga atoms into bulk layers.
These calculations are compared with the results of recent
experiments.
Determination of Molecular Orientational Distribution Using Surface Second-Harmonic Generation Analyzed by the Five-Layer Model and the Modified Maximum-Entropy Method
Authors: Jeong-Geun Yoo Jeong-Geun Yoo , Byoungchoo Park Byoungchoo Park , Takahiro Sakai Takahiro Sakai , Yoshitaka Kinoshita Yoshitaka Kinoshita , Hajime Hoshi Hajime Hoshi , Ken Ishikawa Ken Ishikawa , Hideo Takezoe Hideo Takezoe
Published: October 2002

We have determined the molecular orientational distribution functions
(ODFs) at air and substrate interfaces for unrubbed and rubbed
films of polymer possessing second-harmonic generation (SHG) active
side chains. Using a thick polymer film and four different optical
geometries, the surface SHG signals from the two interfaces could be
successfully separated. To theoretically analyze the surface SHG
results, we used the five-layer model, in which a five-layered system
consisting of air, an unrubbed or rubbed upper SHG active layer, a SHG
inactive polymer bulk layer, a lower SHG active layer and a substrate
was considered. The local field factors for both active layers were
deduced from the boundary conditions among these five layers. In
order to obtain ODFs of the side chains at two SHG active layers,
the modified maximum-entropy method was used. After achieving the best
fit of the theoretical SHG intensities to the experimental results, we
unambiguously determined the unbiased ODFs together with
information on the in-plane axial and the polar order parameters for
the side chains at the air-polymer and substrate-polymer
interfaces of unrubbed and rubbed polymer films.
Multiple Scattering Approach to Pd L3-Edge X-Ray Absorption near Edge Structure Spectra for Small Pd Clusters with Hydrogen Adsorption and Absorption
Authors: Ohtani Kunihiro , Fujikawa Takashi , Kubota Takeshi , Asakura Kiyotaka , Iwasawa Yasuhiro
Published: October 2002

Recent studies on Pd L3-edge X-ray absorption near edge structure (XANES)
spectra for pure small Pd clusters show that the spectra are strongly influenced
by hydrogen adsorption and absorption. In this paper, the full multiple scattering
method is applied to study the difference in measured spectra. The calculated
XANES spectra are not so sensitive to the detailed positions and the electronic
structures of the interacting hydrogen atoms, however they are sensitive to the
induced structural and electronic state change in the host small Pd clusters. The
size effect on the peak at ∼7 eV from the edge is well explained by the induced
lattice expansion after hydrogen absorption.
Study of Pt Bottom Electrodes using High-Temperature Sputtering for Ferroelectric Memories with SrBi2Ta2O9 (SBTO) Film
Authors: Nasu Toru , Kibe Masaki , Uemoto Yasuhiro , Fujii Eiji , Otsuki Tatsuo
Published: October 2002

Pt bottom electrodes for SrBi2Ta2O9 (SBTO) capacitors have been investigated for use in
nonvolatile memories. A Pt thin film which is sputtered at a temperature of 300°C consists of
enlarged columnar grains, while a film sputtered at room temperature consists of fibrous columnar
grains. The formation mechanism of enlarged grains of the Pt film sputtered at 300°C is due to the
fact that the film structure changes with substrate temperature based on the structure-zone model.
The Pt bottom electrode which consists of the enlarged grains results in a decrease in the Ti diffusion
path, leading to effective adhesion of Pt to a SiO2 film.
Structural and Electrical Properties of Crystalline CeO2 Films Formed by Metalorganic Decomposition
Authors: Fukuda Hisashi , Miura Miho , Sakuma Shigeyuki , Nomura Shigeru
Published: October 2002

Crystalline CeO2 films were formed on a Si (100) substrate by metalorganic decomposition at
temparatures ranging from 600°C to 800°C. As-deposited films were in the amorphous state
and were completely transformed to crystalline CeO2 above 600°C. However, during
crystallization in oxygen atomosphere, a reaction between CeO2 and Si occurred at the interface,
which resulted in the formation of a thin interfacial SiO2 layer. Capacitance-voltage
measurement on these films showed good dielectric properties with a dielectric constant of 15,
which is more than three times higher than that of SiO2. The modified structure of
CeO2/SiO2/Si is expected to be suitable for the dielectric layer in an integrated circuit, in place
of conventional dielectric films such as those of SiO2 or Si3N4.
In Situ X-Ray Diffractometry of Cristobalite Formation during High-Temperature Oxidation of SiC Films
Authors: Toshiki Kingetsu Toshiki Kingetsu , Kenjiro Ito Kenjiro Ito , Masaharu Takehara Masaharu Takehara
Published: October 2002

We studied the kinetics of β-cristobalite formation with the coexistence of amorphous silica on polycrystalline β-SiC films during high-temperature oxidation in air, by in situ X-ray diffractometry using an imaging plate. The kinetics was found to obey parabolic laws. The apparent activation energy Q of cristobalite formation estimated in our experiments suggested a possibility that Q might be significantly larger than reported previously for oxide growth on SiC. Possible causes for this large value were discussed.
Formation of Ultra-Shallow and Low-Reverse-Bias-Current Tantalum-Silicided Junctions Using a Si-Encapsulated Silicidation Technique and Low-Temperature Furnace Annealing below 550°C
Authors: Ino Kazuhide , Taniguchi Yoshiyuki , Ohmi Tadahiro
Published: October 2002

Low-temperature processing, below 550°C, has been developed to form ultra-shallow, low-leakage, and low-contact-resistance junctions with tantalum silicide. We have experimentally
demonstrated that the amount of residual defects after ion implantation and subsequent low-temperature annealing is strongly dependent on the substrate dopant concentration for both n
+
p and
p
+
n junctions. It is also confirmed that ion implantation through Ta is not the main factor inducing
larger leakage due to metal-knock-on. As a result, ultra-low leakage current (7.8×10-10 A/cm2 and
6.6×10-10 A/cm2 for n
+
p and p
+
n junctions at reverse-bias of 5 V) and ultra-shallow junction depth (70
nm and 40 nm for n
+
p and p
+
n junctions) have been achieved in Ta-silicided junctions at an annealing
temperature of as low as ∼550°C, by employing an ultraclean ion implanter, Si-encapsulated
silicidation, and low-dopant-concentration substrate.
Correlation between Light-Induced Degradation and Structural Inhomogeneities in Hydrogenated Amorphous Silicon Prepared under High-Rate Deposition Conditions
Authors: Sakikawa Nobuki , Tamao Masaki , Miyazaki Seiichi , Hirose Masataka
Published: October 2002

The structural inhomogeneities of hydrogenated amorphous silicon (a-Si:H) prepared at high-deposition rates (20–27 Å/s) have been studied by the small angle X-ray scattering (SAXS) technique by changing the rf-electrode (cathode) bias voltages for controlling the ion flux impinging on the growing film surface. The total bonded hydrogen contents of the deposited films are independent of dc-bias, while light-induced degradation is significantly suppressed at the cathode bias V
c=+25 V. It is found that structural fluctuation in the range of 10–400 Å as evaluated by SAXS is reduced to about one half at V
c=+25 V in comparison with that of conventional deposition conditions at a rate of ∼1 Å/s.
Dependence of Photodarkening on Alloy Composition of CdSxSe1-x Nanocrystals in Glasses
Authors: Ohkuni Tadaki Miyoshi , Katsuhide Shiraishi Katsuhide Shiraishi , Naoto Matsuo Naoto Matsuo
Published: October 2002

Photodarkening has been investigated in
CdSxSe1-x
-doped glasses using luminescence
and electron spin resonance (ESR).
Photodarkening does not occur
when the wavelength of the laser light is longer than 640 nm,
even if the laser light is absorbed by glasses.
This result is explained by the two-step excitation process.
Lateral Overgrowth of Thick GaN on Patterned GaN Substrate by Sublimation Technique
Authors: Wang Jie , Tottori Satoru , Sato Hisao , Hao Mao-Sheng , Ishikawa Yasuhiro , Sugahara Tomoya , Yamashita Kenji , Sakai Shiro
Published: October 2002

The lateral overgrowth of thick GaN has been attempted using the sublimation
method. The lateral overgrowth of 60 µm on SiO2 mask, which is about three times larger than the vertical growth,
was obtained by one hour of growth at 995°C, with the stripe windows in the <1100>
direction of GaN. Transmission electron microscopy (TEM) shows that the extension of threading dislocations is terminated at the
SiO2/GaN interface. The dislocation density is about 109 cm-2 above the window areas, and is
reduced to 106 cm-2 in the lateral overgrowth region on SiO2.
Quantum Chemical Study on the Oxidation of Hydrogen-Terminated Silicon Surface by Oxygen Anions
Authors: Tachibana Akitomo , Sakata Ken , Sato Takahiro
Published: October 2002

The oxidation mechanism of hydrogen-terminated Si(111) surface by oxygen anions
has been studied using ab initio molecular orbital method. We have found that oxygen
anions are stable in a cage of silicon clusters, which is a local model of the hydrogen-terminated
Si(111) surface augmented by an extended model of periodic boundary
condition. Oxygen anions can attack Si atoms to form a penta-coordinated complex, which
will lower the diffusion barrier for oxygen anion transfer into the Si bulk. An oxygen anion
is inserted into a Si–Si bond to form a local Si–O–Si structure. The stabilization energy is
enhanced if the deformation energy in the local Si–O–Si structure is released. That the
oxidized Si has a tendency to accept additional oxygens is concluded based on a series of
cluster model calculations assuming that the crystallographic strain is completely relaxed.
Surface Crystal Structure of Magnetite Fe3O4(110)
Authors: Oda Yuko , Mizuno Seigi , Todo Sakae , Torikai Eiko , Hayakawa Kazunobu
Published: October 2002

The surface crystal structure of magnetite Fe3O4(110) was studied by low-energy electron diffraction (LEED). A clean surface was obtained after sputtering and annealing at 840 K. The clear LEED patterns show fractional order spots corresponding to a (3×1) surface reconstruction with missing spots. The missing spots indicate a glide plane symmetry of the (3×1) surface. Moreover, the LEED patterns have two-fold rotational symmetry, the surface structure should be p2m
g-(3×1) or double domain of p1g1-(3×1). The same glide plane symmetry of the reconstructed surface structure and the ideal surface structure of Fe3O4(110) shows a strong relation between surface and bulk structures. We propose one possible model that corresponds to the p2m
g-(3×1).
Patterns Around the (110) Plane of Field Emission Microscope Images of Tungsten Tips
Authors: Sato Mieko , Nisikawa Osamu
Published: October 2002

Two types of field emission micropcope (FEM) images of a O2–W adsorption system are
observed. While some of the Field Emission Microscope images appear to be similar to
the field ion micropcope (FIM) images of clean W tips, the other images exhibit patterns
which look as if two different patterns overlap. The relative structure and position of
two types of adsites on various crystallographic planes of a hemispherical surface with
an ideal atomic structure are assumed, and two types of (FEM)
images are examined. Such examination can also give an interpretation for the dark
rectangular patterns around {110} planes usually observed on the (FEM)
images of W tips cleaned by annealing.
Study on Zr–Si/W(100) Surface at High Temperatures by Combined Surface Analysis Techniques
Authors: Kawano Takashi , Kimura Yoshihide , Shimizu Ryuichi
Published: October 2002

The basic mechanism of electron emissivity of a Zr–Si/W(100) surface, which
has attracted much attention as a thermal field emitter for practical use, was
studied by Auger electron spectroscopy, ion scattering spectroscopy and work
function measurements. The results show that the topmost atomic layer consists
of Zr and Si at operating conditions (∼1300 K, 10-9 Torr), the work function of
which is slightly reduced by an order of half an eV from that of a clean W(100)
surface.