bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Temperature Growth of ZnSe/GaAs Using Post-Heated Molecular Beams
Authors: Ohishi Masakazu , Saito Hiroshi , Fujisaki Yasunori , Hiroshi Torihara Hiroshi Torihara , Iminjan Ablet Iminjan Ablet
Published: February 2005

MBE growth of ZnSe/GaAs could be successfully performed at the substrate temperature as low as of 100°C using the molecular beams post-heated at 600°C both for Zn and Se by means of modified Knudsen cells composed of the effuser and the post-heating zone. ZnSe epilayers grown at 100-150°C showed the strong I2 bound exciton line and almost no other luminescence such as donor-acceptor pair, Y, S and deep emission at 4 K.
Order-Disorder Transition in Sputter-Deposited Silver-Zinc Alloy Films
Authors: Maeda Yoshihito , Tetsuroh Minemura Tetsuroh Minemura , Hisashi Andoh Hisashi Andoh
Published: February 2005

An order-disorder transition between β′ and β phases was observed to take place reversibly at 510 K in sputter-deposited AgZn alloy films of 30 nm thickness. The β′ phase was found to exist in the as-deposited alloy film and the transition could be described by the order parameter of Bragg-Williams theory.
High Contrast of Scanning Ion Microscopy Images Shows Element Segregation
Authors: Setsuo Nomura Setsuo Nomura , Hiroyasu Shichi Hiroyasu Shichi
Published: February 2005

Scanning ion microscopy (SIM) provides image contrast clearly higher than that of scanning electron microscopy (SEM). SEM and SIM images of the same sample have been taken in the same instrument under the same field of view conditions, and then compared. SIM reveals element segregation, but SEM does not. It is shown that the elemental contrast of SIM, when using positive secondary ions as the imaging signal, is made by variation of the secondary ion yield of the implanted primary beam element. The variation is caused by differences of sample elements. The high contrast provided by SIM gives valuable information about elements and microcrystallites in material science.
Bulk Plasmons in Solid C60
Authors: Saito Yahachi , Shinohara Hisanori , Akinori Ohshita Akinori Ohshita
Published: February 2005

Electron energy-loss spectra in a low loss region have been obtained from solid C60 by a 200 keV transmission electron microscope equipped with an electron energy analyzer. Bulk plasmons are observed at two characteristic energies, 6.5 and 26 eV, being attributed to collective oscillation of π-electrons, and to that of all the valence electrons (both the π- and σ-electrons), respectively.
Substitution Effect of Rare Earth Elements for Y in Pb-Sr-Y-Ca-Cu-O with “1212” Structure
Authors: Adachi Seiji , Adachi Hideaki , Kentaro Setsune Kentaro Setsune , Kiyotaka Wasa Kiyotaka Wasa
Published: February 2005

The superconducting transition temperature (T
c) and lattice constants of “1212” lead cuprate, (Pb/Cu)Sr2(Ln/Ca)Cu2O
z
(Ln=Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu and Y), were investigated. (Pb0.75Cu0.25)Sr2(Ln0.4Ca0.6)Cu2O
z
ceramics were prepared by sintering at 1000°C for 1 h in oxygen. Obtained ceramics were annealed at 800°C for 24 h in oxygen and subsequently quenched. Linear correlation between lattice constants and ionic radii of Ln was observed in the “1212” phases. The T
c value increased with decreasing ionic radii of Ln. The Ln=Lu sample exhibited a T
c (zero resistivity) of 61 K in our oxperiments.
In Situ Preparation of Superconducting Bi2Sr2Can-1CunOy (n=1∼5) Thin Films by Molecular Beam Epitaxy Technique
Authors: Ichiro Tsukada Ichiro Tsukada , Kunimitsu Uchinokura Kunimitsu Uchinokura
Published: February 2005

Superconducting Bi2Sr2Ca
n-1Cu
n
O
y
(n=1∼5) thin films have been prepared in situ by molecular beam epitaxy with highly condensed ozone as oxidizing gas. All films including thermally metastable phases of n=4 and 5 were obtained by sequential shutter control, and even the n=1 phase film showed superconductivity. The surface of the n=1 phase film was observed by reflection high-energy electron diffraction, and the modulated structure was clearly observed.
Organic Optical Storage Medium with a Read-Out Stability under 1 mW Laser Irradiation
Authors: Kobayashi Setsuo , Iwasaki Kishiro , Sasaki Hiroshi , Oh-hara Shuichi , Katayose Mariko Nishizawa
Published: February 2005

The basic characteristics of new naphthalocyanine derivatives used as a recording layer for a write-once optical storage medium were studied. Read-out stability could be improved by mixing two types of naphthalocyanines: one had a bulky structure with large side chains on the central atom, while the other had a flat structure. The stability of the medium under 1 mW laser irradiation for read-out was substantially improved by a hundredfold times compared with that of a single-component system.
Preparation of High-Tc Superconductor in the (BiPbSrCaCuO) System by Hot-Pressing*
Authors: Anna Tampieri Anna Tampieri , Gian Nicola Babini Gian Nicola Babini
Published: February 2005

Superconducting Bi-Pb-Sr-Ca-Cu-O ceramics were sintered by the hot-pressing technique. The densification mechanism was investigated at 800°C and 850°C and a densification phenomenology has been proposed. Samples hot pressed at 850°C showed high density and T
c≈110 K.
Photoconduction of Black Phosphorus in the Infrared Region
Authors: Baba Mamoru , Nakamura Yoshitaka , Shibata Kiyotaka , Morita Akira
Published: February 2005

Photoconduction of elemental black phosphorus has been investigated for the first time in the spectral range from 1.5 µm to 5.5 µm, including its fundamental absorption edge. It has been found that black phosphorus shows a broad spectral response from the absorption edge to the visible region and a linear response to the light intensity, which has a fairly response even at room temperature. These results suggest that black phosphorus can be applicable to IR detecting devices. In addition, the direct allowed transition at the absorption edge was confirmed and its temperature dependence was measured.
Effects of Oxygen Addition on Diamond Film Growth by Electron-Cyclotron-Resonance Microwave Plasma CVD Apparatus
Authors: Nunotani Masayuki , Komori Masaaki , Yamasawa Masahiro , Fujiwara Yasufumi , Sakuta Ken , Kobayashi Takeshi , Nakashima Shinichi , Minomo Shoichiro , Taniguchi Michio , Sugiyo Masato
Published: February 2005

Diamond thin films have been grown by an electron-cyclotron-resonance (ECR) microwave plasma chemical vapor deposition (CVD) apparatus under the addition of oxygen to the host ambient gas of a mixture of CO and H2 gas. Although the amount of oxygen was very minute (0-6% vol. fraction), significant changes due to the oxygen were brought about in the growth properties and the film crystallinity. The Raman spectroscopy revealed a dramatically improved film crystallinity and the film was dominated by the grain growth, resulting in the faceted morphology. With increase in the oxygen up to 4.55%, the visible cathodeluminescence (CL) intensity grew by more than ten times. However, the CL spectrum indicated an appearance of one or two extra recombination centers depending on the amount of oxygen.
Comments on Stranski-Krastanov Growth of Bi and Ag on Si(100)
Authors: P. Akhter P. Akhter , A. Baig A. Baig
Published: February 2005

T. Yamada and H. Abe (Jpn. J. Appl. Phys. 29 (1990) L1192) have interpreted their results of adsorption of Bi and Ag on Si(100) as Stranski-Krastanov growth. We have analysed their data and have shown that both the metals grow in island mode instead of Stranski-Krastanov.
Efficient Visible Photoluminescence from Porous Silicon
Authors: Nobuyoshi Koshida Nobuyoshi Koshida , Hideki Koyama Hideki Koyama
Published: February 2005

It is shown that UV-excited porous Si (PS) exhibits an efficient visible photoluminescence (PL) at room temperature. The PS layers were formed by anodization of p-type and n-type single-crystal Si wafers in aqueous HF solutions. The peak wavelength of PL spectra depends on the anodization parameters including the resistivity and the conduction type of Si substrates. The PL spectra can be tuned to a higher energy side by either adjustment of the anodizing conditions or chemical etching after anodization. These remarkable results can be interpreted as a result of quantum size effects in PS.
Preparation and Properties of Single Crystal CuAlSe2 Film
Authors: Yoshio Morita Yoshio Morita , Tadashi Narusawa Tadashi Narusawa
Published: February 2005

Epitaxial CuAlSe2 film has been grown on the GaP(100) substrate by molecular beam epitaxy, and its optical and electrical properties have been characterized. The spectrum of optical reflectance suggests that the band gap of the film is about 2.7 eV, which agrees with that of the bulk material. The photoluminescence spectrum at 77 K showed no band edge emission, but only deep level-related emissions ranging from 520 nm to 870 nm. The CuAlSe2 sample exhibits n-type conductivity with the resistivity of 0.02 Ω·cm, the carrier concentration of 4×1018 cm-3 and the mobility of 60 cm2·V-1·s-1.
Effects of Electron Irradiation on the Structural Change in Oriented (Bi0.75Pb0.25)2Sr2Ca2Cu3O10 Superconductors
Authors: Ishibashi Teruo , Yoda Noriyuki Inuishi
Published: February 2005

Oriented sintered (Bi0.75Pb0.25)2Sr2Ca2Cu3O10 pellets have been irradiated up to 2×1018/cm2 with 3 MeV electrons at 370 K. By X-ray line broadening analyses, the amount of disordered portion in the c-axis direction increased by about 20% on irradiation of 2×1018/cm2. The intensity of Ca LMM Auger electrons decreased with increasing irradiation. The transition temperature onset remained unchanged at 110.1 K by irradiation, while the transition temperature offset decreased from 101.2 K to 94.7 K at the maximum irradiation dose. The above observations have been explained by the formation of the disordered portion in the grain surface by electron irradiation, which results in the reduction of the superconducting grain connection.
Electrical Transport in the Ag-Bi2Sr1.8Ca1.2Cu2Oy Composite System
Authors: Chen J. J. Lin
Published: February 2005

We have measured the resistivity of the Ag-Bi2Sr1.8Ca1.2Cu2O
y
composite system with Ag volume fraction p
Ag ranging from 0.00 to 1.00. We find, for the samples with p
Ag<0.6, that the addition of Ag slightly decreases the superconducting transition temperature of Bi2Sr1.8Ca1.2Cu2O
y
. For the samples with p
Ag>0.6, no zero-resistivity state is observed. The variation of the room-temperature resistivity with p
Ag indicates a three-dimensional percolating Ag matrix occurring at p
Ag≈0.17.
Preparation of Superconducting Ba2YCu3O7-y/Ag Composite Films by the Dipping-Pyrolysis Process Using Metal Naphthenates at 750°C
Authors: Kumagai Toshiya , Manabe Takaaki , Tsunoda Tatsuo , Wakichi Kondo Wakichi Kondo , Susumu Mizuta Susumu Mizuta
Published: February 2005

Superconducting Ba2YCu3O7-y
/Ag composite films were prepared on yttria-stabilized zirconia substrates by the dipping-pyrolysis process. Metal naphthenates were used as starting materials. Homogeneous Ba-Y-Cu-Ag solutions with (Ag/BYCO) molar ratios of 0-1.0 were spin-coated onto the substrates and pyrolyzed at 500°C. Subsequently, these prefired films were heat-treated at 750°C under a low-oxygen partial pressure (=2×10-4 atm) followed by higher-p(O2) annealing. High superconducting transition temperatures, T
c,onset(s)'s and T
c,zero$(r)'s, o
f 88 K-90 K
w
e
r
e
o
b
t
a
i
n
e
d
f
o
r
t
h
e
c
o
m
p
o
s
i
t
e
f
i
l
m
s
w
i
t
h (A
g/B
Y
C
O) m
o
l
a
r
r
a
t
i
o
s
o
f 0.1-0.5.
An Experiment for Estimating Inclination of Recorded Magnetization in an Obliquely Metal-Evaporated Tape by Using the Bitter Pattern Technique
Authors: Sakurai Tomoaki , Kitakami Osamu , Kimiyoshi Goto Kimiyoshi Goto
Published: February 2005

Inclination of recorded magnetization in an obliquely metal-evaporated (ME) tape is estimated by the Bitter pattern technique. Although the contrast of the Bitter pattern evolved in a magnetic field of various directions to the film plane is generally asymmetric with respect to recording transitions, it becomes symmetric only when that magnetic field is applied in a direction determined by the recorded magnetization. For the Co-Ni-O film recorded at 1.5 kFCl, the inclination of magnetization is estimated to be about 40°. It is also shown that this value of the inclination agrees well with the theory.
ICTS of MOS Interface States Enhanced by Gold Diffusion
Authors: Yoshida Haruhiko , Hirohiko Niu Hirohiko Niu , Seigô Kishino Seigô Kishino
Published: February 2005

An enhancement of interface states of Si MOS diode by gold diffusion is observed by the isothermal capacitance transient spectroscopy (ICTS) measurement. The observed ICTS spectra are identified as the interface states with the help of numerical simulation. Although the gold diffusion is accompanied by thermal annealing, the effect of the thermal annealing on the interface states is eliminated with the use of an extra annealing at a low temperature in a nitrogen ambient. It is also ascertained that the interface states enhanced by the gold diffusion increase as the density of diffused gold increases.
Bulk Single Crystal Growth of Bi12TiO20 by the Czochralski Method
Authors: Okano Yasunori , Wada Hiroyuki , Miyazawa Tsuguo Fukuda
Published: February 2005

We have confirmed that photorefractive Bi12TiO20(BTO) crystal has incongruent melting properties and the upper limit for growing BTO single crystals is found to be 11 mol% TiO2. BTO single crystals 20 mm in diameter and 30 mm in length are successfully grown from a Bi2O3-rich melt by the Czochralski method. These crystals are light brown in color and transparent in the range over the absorption edge, near 450 nm. Growth rates of less than 0.5 mm/h prevent the grown crystal from excess Bi2O3 as inclusions. Facet and core characteristics are found to be dependent on the growth directions.
Zero-Field Time-of-Flight Measurements of Electron Diffusion in P+-GaAs
Authors: Lovejoy M. L. , Keyes B. M. , Klausmeier-Brown M. E. , Melloch M. R. , Ahrenkiel R. K. , M. S. Lundstrom M. S. Lundstrom
Published: February 2005

Minority electron diffusivities in p+-GaAs-doped N
A≃1.4×1018 and ∼1019 cm-3 have been measured in zero-field conditions with an extension of the zero-field time-of-flight technique. Extension of the technique to make it applicable to heavily doped p+-GaAs is described and zero-field data are discussed. Unexpectedly, majority carrier drag effects are not evident in a comparison of this data with recently reported high-field data. Low zero-field mobility of electrons in p+-GaAs has important implications for high-speed devices such as heterojunction bipolar transistors.
Microstructure and Microwave Properties of YBa2Cu3O7-δ Thin Films Grown on NdGaO3
Authors: Young K. H. , G. V. Negrete G. V. Negrete , J. Z. Sun J. Z. Sun
Published: February 2005

High-quality YBa2Cu3O7-δ thin films have been grown on NdGaO3(001) substrates by in situ laser ablation. The best transition temperature determined by AC susceptibility is 88.9 K and transition width is as narrow as 0.4 K. Critical current density of 1.2×106 A/cm2 at 77 K was obtained. However, the loss tangent of this substrate is measured to be 3×10-4 at 77 K and 5 GHz which is ten times poorer than that of LaAlO3. A 2.3 GHz resonator made from films on NdGaO3 exhibited a low power Q of 4500 which is very close to the calculated limit based on the loss tangent data. The microwave performance is thus severely limited by the substrate loss in our test geometries.
Characterization of Y-Ba-Cu-O Thin Films on Metallic Substrates Using Co-Evaporation Technique
Authors: Satoh Kouki , Yoshihara Masashi , Nakajima Minoru , Hara Tsukushi , Ishii Hideo , Yamamoto Takahiko
Published: February 2005

A tape wire having the structure of YBCO/YSZ/Hastelloy, of which a YBCO layer was fabricated by a co-evaporation technique, was prepared. The critical current density J
c of 2.3×104 A/cm2 at 77 K and 0 T was obtained by using an rf coil and a dc bias at substrate heater during the YBCO layer growth, which enabled denser surface morphology in the YBCO layer. It was considered that the surface smoothness of a YSZ buffer layer had a large influence on the degree of c-axis orientation of the YBCO layer from the view of microstructural observation by transmission electron microscopy (TEM).
Characterization of Y1-xCaxBa2Cu4O8 (x=0.0∼0.1) with Double Cu-O Chains by Raman Spectra
Authors: Kodama Yasuharu , Ikeda Sakae Tanemura
Published: February 2005

Raman spectra of Y1-x
Ca
x
Ba2Cu4O8 (x=0.0, 0.02, 0.05 and 0.1) ceramic samples synthesized under high oxygen pressure were investigated. Seven clear peaks assigned to Ag modes were observed for the sample with x=0. With increasing x, the peaks at 238 cm-1, 332 cm-1, 430 cm-1 and 590 cm-1 were broadened. The origin of the broadening of the peaks at 238 cm-1 and 590 cm-1 is considered to be the destruction of the double Cu-O chains due to the substitution of Ca for Y.
Line Shape Functions of Quantum-Box Lasers
Authors: Yamanishi Tsukuru Ohtoshi
Published: February 2005

Homogeneous line shape functions for quantum-box lasers are, for the first time, estimated considering the non-Markovian effect. Carrier-carrier interactions within a box and between neighboring boxes are considered as physical processes responsible for polarization damping. The line shape functions of quantum-box lasers are extremely narrow Gaussian functions. The influence of the long dephasing time on the lasing characteristics of quantum-box lasers is briefly discussed, raising questions on the validity of the conventional rate equation approximation.
Measurement of the Activation Energy of Tantalum Silicide Growth on Silicon by Rapid Electron Beam Annealing
Authors: Mahmood F. , Ahmed H. , Suleman M. , Ahmed M. M.
Published: February 2005

A rapid electron beam annealing technique has been used to induce the reaction of 1150±50 Å deposited tantalum films on single crystal silicon. The annealing was carried out at temperatures ranging from 750°C to 1000°C, in 25°C increments, for a dwell time of 2 s in each case. The tantalum silicide films were characterized by sheet resistance measurements and Auger electron spectroscopy depth profiling. The resistivity of the completely reacted thin tantalum silicide films was 45-50 µΩ-cm. The very accurate control of the time-temperature profile that was possible in the electron beam system enabled a detailed study of the growth rate of tantalum silicide. An activation energy of 3.0-0.2 eV was deduced for the growth of tantalum disilicide from the solid-phase reaction between the metal and the silicon substrate.
Thomson Scattering Diagnostics of an ECR Processing Plasma
Authors: Sakoda Tadanori , Momii Shinji , Uchino Kiichiro , Muraoka Katsunori , Bowden Mark , Maeda Mitsuo , Manabe Yoshio , Kitagawa Masatoshi , Kimura Tadashi
Published: February 2005

Information of electron behaviour in processing plasmas was obtained for the first time by the Thomson scattering measurements of electron cyclotron resonance (ECR) plasmas after overcoming various difficulties of the experiment. At relatively high microwave power of 500 W and high argon gas pressure of 2 mTorr, the measurements yielded electron temperature and density to be 9±3 eV and (9±2)×1017 m-3, respectively. Ways of improving detection limit and/or accuracy are discussed.
Two-Dimensional Device Simulator VENUS-2D/B for Amorphous Silicon Thin-Film Transistors Using a Gap-State Model
Authors: Ishizuka Tatsumi , Sumino Kazuki , Hirose Yasuroh Iriye
Published: February 2005

A two-dimensional device simulator VENUS-2D/B for amorphous silicon thin-film transistors has been developed. For the efficient numerical simulation of amorphous silicon devices, the trapped electron density in the band gap is modeled by the combination of exponential functions. The current-voltage characteristics of an inverted-gate hydrogenerated amorphous silicon thin-film transistor were simulated by VENUS-2D/B.
Temperature Dependence of Photoluminescence Decay Time in Tunneling Bi-Quantum-Well Structures
Authors: Sugiyama Yoshihiro , Tackeuchi Atsushi , Tsuguo Inata Tsuguo Inata , Sunichi Muto Sunichi Muto
Published: February 2005

We studied the nonresonant electron tunneling time in tunneling bi-quantum-well structures with a pump-probe photoluminescence (PL) system using optical mixing. The PL decay time of narrow wells for an Al
x
Ga1-x
As (x=0.51) barrier of 4.0 nm, determined by tunneling, decreases from 40 ps to 24 ps as the temperature increases from 6 K to 132 K. We attribute this to electrons in an exciton state thermalizing into free electrons having a faster tunneling rate.
Surface Analysis of C-Axis-Oriented YBa2Cu3O7-X Thin Films by QMS, XPS and LEED: Effects of In-Vacuum Annealing
Authors: Tanaka So , Nakamura Takao , Iiyama Michitomo , Yoshida Noriyuki , Takano Satoru
Published: February 2005

The effects of in-vacuum annealing on the crystallinity and superconductivity in the surface region of YBa2Cu3O7-X
thin films were investigated by QMS, XPS and LEED. Contaminated and disordered layers, which were nonsuperconducting phase, covered the film surface after being exposed to air. Surface contaminants are removed by annealing at 350°C in ultra high vacuum. The orthorhombic YBa2Cu3O7-X
(001) structure and superconducting phase are obtained at the outermost surface after annealing at 350-400°C.
EXAFS Study on the Local Structure around Cu in the Nitrogen-Annealed Bi1.6Pb0.4Sr2Ca1Cu2Oy Superconductor
Authors: Kuriyama Nobuya , Hiroyuki Nasu Hiroyuki Nasu , Kanichi Kamiya Kanichi Kamiya
Published: February 2005

The effect of nitrogen-annealing on the local structure around Cu in the high-T
c superconductor-Bi1.6Pb0.4Sr2Ca1Cu2O
y
has been studied using the extended X-ray absorption fine structure (EXAFS). In the CuO2 plane, two Cu-O distances of 1.86 Å and 1.91 Å were observed for the nitrogen-annealed sample (T
c=91 K), while only one distance of 1.90 Å was observed for the untreated one (T
c=71 K). The coordination number of Cu was changed from about 5 to about 4 by the nitrogen annealing.
Nearly Untwinned Superconducting Bi2Sr2CuOy Thin Films Grown on (Y, Nd)AlO3 (001) Substrate
Authors: Ichiro Tsukada Ichiro Tsukada , Kunimitsu Uchinokura Kunimitsu Uchinokura
Published: February 2005

Superconducting Bi2Sr2CuO
y
thin films were prepared in situ by molecular beam epitaxy with pure ozone gas. Films were deposited on SrTiO3 (001) and (Y, Nd)AlO3 (001) substrates, and their surface structures (Bi-O layer) were observed by reflection high-energy electron diffraction. While the film on the SrTiO3 substrate had incommensurate modulated structures equivalently along both the SrTiO3 [110] and SrTiO3 [1̄10] directions, the modulated structures of major domains of the film on the (Y, Nd)AlO3 substrate ran along the (Y, Nd)AlO3 [100] direction. The origin of the in-plane orientation is related to the in-plane lattice constants of (Y, Nd)AlO3 and Bi2Sr2CuO
y
.
Influence of Ozone Concentration on the Preparation of Stoichiometric Superconducting Y-Ba-Cu-O Films by a Metalorganic Chemical Vapor Deposition Technique
Authors: Ohnishi Hiroshi , Harima Hiroshi , Tachibana Yoshiyuki Goto
Published: February 2005

As-grown, nearly stoichiometric YBa2Cu3O7-x
superconducting films were prepared by a metalorganic chemical vapor deposition technique on SrTiO3(100) substrates at 650°C. This letter describes how the film characteristics change with the concentration of ozone in O2 gas. It was found that the superconducting characters of nearly stoichiometric films can be improved by optimizing the ozone concentration. At 3% concentration of ozone, a film with the zero-resistive temperature of 85 K was obtained at a composition of Y:Ba:Cu=1.1:2:2.7. It had a smooth surface morphology and a good c-axis orientation.
Phases and Third-Order Optical Nonlinearities in Tetravalent Metallophthalocyanine Thin Films
Authors: Hosoda Masahiro , Wada Tatsuo , Yamada Akira , Anthony F. Garito Anthony F. Garito , Hiroyuki Sasabe Hiroyuki Sasabe
Published: February 2005

The third-order optical susceptibilities χ1111
(3)(-3ω; ω, ω, ω)s
f
o
r
t
w
o
d
i
f
f
e
r
e
n
t
p
h
a
s
e
s
i
n
v
a
n
a
d
y
l
a
n
d
t
i
t
a
n
y
l
p
h
t
h
a
l
o
c
y
a
n
i
n
e (V
O
P
c
a
n
d
T
i
O
P
c) v
a
c
u
u
m-d
e
p
o
s
i
t
e
d
t
h
i
n
f
i
l
m
s
a
r
e
d
e
t
e
r
m
i
n
e
d
b
y
o
p
t
i
c
a
l
t
h
i
r
d-h
a
r
m
o
n
i
c
g
e
n
e
r
a
t
i
o
n (T
H
G) m
e
a
s
u
r
e
m
e
n
t
s
a
t
w
a
v
e
l
e
n
g
t
h
s 1543 n
m
a
n
d 1907 n
m. T
h
e
r
m
a
l
a
n
n
e
a
l
i
n
g
c
a
u
s
e
s
a
p
h
a
s
e
t
r
a
n
s
i
t
i
o
n
w
h
i
c
h
a
c
c
o
m
p
a
n
i
e
s
a
r
e
d
s
h
i
f
t
i
n
t
h
e
i
r
a
b
s
o
r
p
t
i
o
n
s
p
e
c
t
r
a
a
n
d
a
n
i
n
c
r
e
a
s
e
i
n
t
h
e χ^(3) v
a
l
u
e
o
f 2-5 t
i
m
e
s
i
n
V
O
P
c
a
n
d
T
i
O
P
c
f
i
l
m
s. T
h
e
e
n
h
a
n
c
e
m
e
n
t
o
f
t
h
e
t
h
i
r
d-o
r
d
e
r
o
p
t
i
c
a
l
n
o
n
l
i
n
e
a
r
i
t
i
e
s
i
n
t
e
t
r
a
v
a
l
e
n
t
p
h
t
h
a
l
o
c
y
a
n
i
n
e
f
i
l
m
s
i
s
d
i
s
c
u
s
s
e
d
i
n
t
e
r
m
s
o
f
m
o
l
e
c
u
l
a
r
p
a
c
k
i
n
g.
Substrate Effect on Poling Process of Nonlinear Optical Polymer Films
Authors: Suzuki Akiyoshi , Yoshihiko Matsuoka Yoshihiko Matsuoka , Akira J. Ikushima Akira J. Ikushima
Published: February 2005

The effect of the substrate on the corona poling process of dye-doped poly(methyl methacrylate) films is investigated for nonlinear optics (NLO). It is found that poled films on soda-lime glass exhibit much larger nonlinear susceptibility than do those on fused quartz. This strange result is well explained by considering the volume resistivity of the substrate.
Photocurrent Spectroscopy of Excitonic Transitions in CdZnS/ZnS Strained-Layer Superlattices
Authors: Tetsuichiro Ohno Tetsuichiro Ohno , Tsunemasa Taguchi Tsunemasa Taguchi
Published: February 2005

We report the first observation of excitonic transitions in the photocurrent spectra (PCS) of MQW Cd
x
Zn1-x
S/ZnS (x=0.25) strained-layer superlattices (SLS). In electric field dependent PCS measured at 14 K and at room temperature, we have observed a significant blueshift of the peak energy and photocurrent enhancement with increasing applied field. These results may be fully explained by assuming that this strained superlattice system exhibits a type II band lineup. Preliminary results for photo-detection in the ultraviolet are also presented and these suggest the possibility of producing a photo-modulator in the green to UV region of the spectrum.
β-Relaxation Phenomena of Copolymer of Polyvinylidene and Trifluoroethylene
Authors: Shigenori Utoh Shigenori Utoh
Published: February 2005

Effect of sample conditions on the β-dielectric relaxation phenomena in copolymer of vinylidene fluoride VDF and trifluoroethylene TrFE with 73 and 27 wt.% was studied as a function of temperature under high pressure. We were able to divide the β-relaxation behaviors broadly into two types according to the sample conditions and we also found that they each have dielectric characteristics showing the different pressure dependences.
Formation of Polysilicon Films by Catalytic Chemical Vapor Deposition (cat-CVD) Method
Authors: Hideki Matsumura Hideki Matsumura
Published: February 2005

Silicon films are deposited by a new plasma-free and low-temperature deposition technique, the catalytic chemical vapor deposition (cat-CVD) method, in which deposition gases are decomposed by reactions with a heated catalyzer placed near substrates. It is found that polysilicon films of a grain size of around 0.1 µm can be easily obtained at substrate temperatures lower than 450°C by this cat-CVD method when gas pressure P
g is below a certain critical value, although films are amorphous even for substrate temperatures higher than 450°C when P
g is larger than such a critical gas pressure.
Noncentrosymmetric Structure of Merocyanine J-Aggregate Assembly Studied by Second-Harmonic Generation
Authors: Kajikawa Kotaro , Hideo Takezoe Hideo Takezoe , Atsuo Fukuda Atsuo Fukuda
Published: February 2005

We have found that the assembly of J-aggregates in a merocyanine monolayer Langmuir-Blodgett (LB) film has noncentrosymmetric structure by surface second-harmonic generation (SHG). The chromophores align along an average direction, so that the symmetry is C2v. The pure merocyanine monolayer has a large second-order nonlinear susceptibility χ
z
z
z
=1.3×10-7 esu, because of the noncentrosymmetric domain of J-aggregates. The dissociation of the aggregates occurs by heating, resulting in negligible SHG activity due to random orientation of the chromophore on the surface plane. We also confirmed the long-range anisotropic orientation of the chromophore over several millimeters.
Nonlinear I-V Characteristics of Bi2Sr2CaCu2Ox Thin Films
Authors: Myoren Hiroaki , Takatoshi Ishikawa Takatoshi Ishikawa , Yukio Osaka Yukio Osaka
Published: February 2005

The nonlinear I-V characteristics in magnetic fields of 100 nm-thick Bi2Sr2CaCu2O
x
films on MgO(100) substrates were measured. In addition to the published results on YBa2Cu3O
x
and Tl2Ba2CaCu2O
x
, the present measurement suggests that nonlinear I-V characteristics of high-T
c superconductors are universal and in agreement with a theoretical prediction based on a three-dimensional superconducting “vortex-glass” phase.
Fabrication of Variable-Thickness Bridge Using YBCO Thin Film
Authors: Park Chan Hoon , Tadayuki Kobayashi Tadayuki Kobayashi , Toshinari Goto Toshinari Goto
Published: February 2005

In-situ-grown YBCO thin films were prepared on a MgO substrate by rf magnetron sputtering with a dc-biased substrate holder using a stoichiometric Y1Ba2Cu3O
y
target. The variable-thickness bridges with the bridge length of 80 nm-200 nm were fabricated in these films by means of photolithography and slant evaporation techniques. The current-voltage characteristics of the bridge in rf radiation show the structure of the rf-induced steps over a wide temperature range.
Successive Phase Transitions in Antiferroelectric Liquid Crystal 4-(1-methylheptyloxycarbonyl)phenyl 4'-octylcarbonyloxybiphenyl-4-carboxylate (MHPOCBC)
Authors: Isozaki Tadaaki , Suzuki Yoshiichi , Kawamura Ichiro , Mori Kahoru , Yamamoto Norio , Yamada Yuichiro , Orihara Hiroshi , Ishibashi Yoshihiro
Published: February 2005

A new antiferroelectric liquid crystal (AFLC), 4-(1-methylheptyloxycarbonyl)phenyl 4'-octylcarbonyloxybiphenyl-4-carboxylate (MHPOCBC), was synthesized and an unidentified phase (designated as SmCx) was observed between the paraelectric SmA phase and the antiferroelectric SmCA
* phase by means of thermal, dielectric and electrooptical measurements. Thermal and dielectric studies suggest that the SmA-SmCx phase transition is of the second order and the SmCx-SmCA
* phase transition is of the first order. Two types of electrooptical responses were observed in the SmCx phase: at relatively high temperatures the tristable switching appeared and at low temperatures tetrastables switching was noted. These features are discussed in terms of field-induced transitions.
Characteristics of Plasma-Enhanced Photoemission from Thin Films during Plasma-Assisted Chemical Vapor Deposition
Authors: Okada Tatsuo , Akihiro Nishimi Akihiro Nishimi , Mitsuo Maeda Mitsuo Maeda
Published: February 2005

Plasma-enhanced photoemission spectroscopy has been applied to in situ monitoring of thin-film formation during CH4/Ar rf plasma chemical vapor deposition (CVD). The behavior of the photoemission signal during CVD is described, along with basic characteristics of photoelectric signals in H2 rf plasma.
Reverse Dry Etching Using a High-Selectivity Carbon Mask Formed by Electron Beam Deposition
Authors: Heiji Watanabe Heiji Watanabe , Shinji Matsui Shinji Matsui
Published: February 2005

A reverse dry etching technique using showered electron beam (EB) assisted etching is reported whereby a surface layer of carbon formed on GaAs substrates resulting from EB irradiation of oil vapor in the vacuum system is used as a mask for EB assisted etching. As a result of GaAs reverse pattern transfer, high selectivity is obtained between the mask material and the GaAs substrate. Auger electron spectroscopy (AES) measurements show this mask to be an ultrathin carbon layer. A 0.6 µm linewidth reverse pattern is transferred onto the substrate using this technique.
Preparation of High-Jc Ba2YCu3O7-y Films on SrTiO3 (100) Substrates by the Dipping-Pyrolysis Process at 750°C
Authors: Manabe Takaaki , Kondo Wakichi , Susumu Mizuta Susumu Mizuta , Toshiya Kumagai Toshiya Kumagai
Published: February 2005

Superconducting Ba2YCu3O7-y
films were prepared on SγTiO3 (100) substrates by the dipping-pyrolysis process using metal acetylacetonates as starting materials. Prefired films were heat-treated at 750°C under a low-oxygen partial pressure (p(O2)=2×10-4 atm) and then annealed in O2. The resulting films showed high superconducting transition temperatures; both of the values of T
c,onset(s) and T
c,zero(r) were 89 K. The current-voltage characteristics of the films were measured at 74-86 K. The critical current at 77 K and 0 T was 2.4 A, which corresponds to the critical-current density of 3.9×105 A/cm2.
Second-Harmonic Generation from Y-Type Deposition of N-Acyl-p-Nitroaniline Langmuir-Blodgett Films
Authors: Miyamoto Yasuo , Kaifu Katsuaki , Koyano Takeshi , Minoru Saito Minoru Saito , Masakazu Kato Masakazu Kato
Published: February 2005

The second-order nonlinear optical properties of Y-type-deposited N-acyl-p-nitroaniline Langmuir-Blodgett films are studied. The second-harmonic intensity from the film shows a large anisotropy in the dipping direction and is dependent on the acyl-chain length. The same kind of anisotropy and dependence is observed in UV absorbance. It is indicated that the orientation of the p-nitroaniline group in the molecule is changed by the chain length by means of X-ray diffraction and IR spectroscopy.
Chevron Layer Structure and Focal Conics in Chiral Smectic C Liquid-Crystal Cells Aligned by SiO Oblique Evaporation Technique
Authors: Shin-ichi Kondo Shin-ichi Kondo , Tadashi Akahane Tadashi Akahane
Published: February 2005

Chevron layer structures and focal conics in chiral smectic C liquid crystals were investigated by means of polarizing microscope observation and X-ray analysis for two kinds of cells (parallel cells and antiparallel cells) aligned on obliquely evaporated SiO film. For parallel cells, symmetric chevron layer structures and symmetric focal conics were formed. For antiparallel cells, asymmetric chevron layer structures and asymmetric focal conics were formed.
GaAs Heteroepitaxial Growth on an InP (001) Substrate
Authors: Ichiro Tanaka Ichiro Tanaka , Shunsuke Ohkouchi Shunsuke Ohkouchi
Published: February 2005

We have observed GaAs growth processes on an InP (001) surface thermally cleaned in an arsenic flux using a multichamber ultrahigh-vacuum scanning tunneling microscope (UHV-STM) equipped with a molecular beam epitaxy (MBE) facility. When either 1 monolayer (ML) or 1.5 ML GaAs was deposited on an InP (001) surface, two-dimensional growth was observed. On the other hand, island formation was observed for 2.5 ML GaAs deposition.
High-Resolution Measurements of Nuclear Bragg Scattering from a Synthetic α-57Fe2O3 Crystal
Authors: Kikuta Seishi , Yoda Yoshitaka , Kudo Yoshihiro , Izumi Koichi , Ishikawa Tetsuya , Suzuki Carlos Kenichi , Ohno Hideo , Takei Humihiko , Nakayama Kan , Zhang Xiao Wei , Matsushita Tadashi , Kishimoto Shunji , Ando Masami
Published: February 2005

Nuclear Bragg scattering from a synthesized α-57Fe2O3 crystal was observed with 450 cps at beamline 16 of the Photon Factory. Mössbauer absorption spectra of the scattered beam were measured by oscillating the scatterer crystal while maintaining its Bragg condition. Time distribution of the scattered beam was measured with 300 ps resolution.
Si2H6 Doping of InP in Gas-Source Molecular Beam Epitaxy Using Triethylindium and Phosphine
Authors: Ando Hideyasu , Okamoto Naoya , Adarsh Sandhu Adarsh Sandhu , Toshio Fujii Toshio Fujii
Published: February 2005

Disilane was shown to be an effective alternative gaseous dopant source in gas-source MBE growth of n-type InP using triethylindium and phosphine. The epilayers could be successfully doped to carrier concentrations between 7.8×1016 cm-3 and 1.4×1018 cm-3 with disilane flow rates between 0.6 and 8.5 sccm. From a SIMS depth profile of structures composed of several layers grown with various disilane flow rates, no segregation or memory effects was observed. Electron mobilities of the epilayers were comparable to the best data obtained with other growth method. We also found that the introduction of disilane affects the growth rates of InP layers.
Highly P-Typed Mg-Doped GaN Films Grown with GaN Buffer Layers
Authors: Nakamura Shuji , Masayuki Senoh Masayuki Senoh , Takashi Mukai Takashi Mukai
Published: February 2005

Mg-doped GaN films were grown with GaN buffer layers on a sapphire substrate. Hall-effect measurement of as-grown GaN films showed that the hole concentration was 2×1015/cm3, the hole mobility was 9 cm2/V·s and the resistivity was 320 Ω·cm at room temperature. After the low-energy electron-beam irradiation (LEEBI) treatment, each value became 3×1018/cm3, 9 cm2/V·s and 0.2 Ω·cm at room temperature, respectively. This value of the hole concentration is the highest ever reported for the p-type GaN films and that of the resistivity is the lowest.
Variable Energy Gap in Oxygenated Amorphous Cadmium Telluride
Authors: Espinoza-beltrán F. J. , Sánchez-sinencio F. , Zelaya-Angel O. , Mendoza-Alvarez J. G. , Alejo-Armenta C. , Vázquez-López C. , Farías M. H. , Soto G. , Cota-Araiza L. , Peña J. L. , Azamar-Barrios J. A. , Baños L.
Published: February 2005

A new material, oxygenated amorphous cadmium telluride, is introduced into the II-VI semiconductor compounds family. Amorphous films of this material have been grown by a radio frequency sputtering deposition technique, using a controlled plasma (Ar-O-N) on glass slides substrates positively dc biased. We show that the bandgap of the films can be changed in a controlled way in the range from 1.48 to 2.02 eV depending on the amount of oxygen present in the sample.
AlGaAs/GaAs and AlGaAs/InGaAs/GaAs High Electron Mobility Transistors Grown by Metalorganic Vapor Phase Epitaxy Using Tertiarybutylarsine
Authors: Kikkawa Toshihide , Ohori Tatsuya , Mitani Eizou , Suzuki Masahisa , Hitoshi Tanaka Hitoshi Tanaka , Junji Komeno Junji Komeno
Published: February 2005

We demonstrate the first fabrication of AlGaAs/GaAs and pseudomorphic AlGaAs/InGaAs/GaAs high electron mobility transistors (HEMTs) grown by metalorganic vapor phase epitaxy (MOVPE) using tertiarybutylarsine (tBAs) on 3-inch GaAs substrates. In the drain current-voltage characteristics, sharp pinch-off and excellent saturation were observed for HEMTs grown using tBAs as well as using arsine. A transconductance of 324 mS/mm and the K-factor of 418 mA/V2/mm were obtained using tBAs for n-AlGaAs/GaAs HEMTs with a 0.5-µm gate, while those for n-AlGaAs/InGaAs/GaAs pseudomorphic HEMTs were 350 mS/mm and 480 mA/V2/mm. These results verify that GaAs, AlGaAs, and InGaAs layers grown using tBAs are of sufficiently high quality for HEMT applications.
Hall Effect Measurements on Fine-Grain Poly-Si Thin-Film Transistors Made from Laser-Irradiated Sputter-Deposited Si Film
Authors: Serikawa Tadashi , Shirai Seiiti , Akio Okamoto Akio Okamoto , Shiro Suyama Shiro Suyama
Published: February 2005

N-channel, fine-grain polycrystalline silicon thin-film transistors (poly-Si TFTs) with field-effect mobilities of 185 and 40 cm2/V·s are fabricated from sputter-deposited Si film irradiated with laser light. Carrier concentrations and Hall mobilities are derived from Hall effect measurements at room temperature. Carrier concentrations are similar, but there is a large difference in Hall mobility between the two poly-Si TFTs. Therefore, the increase of field-effect mobility depends on the increase of carrier velocity itself, not on the increase of carrier concentration. It is also found that Hall mobility depends more strongly on potential barrier height than does carrier concentration.
Low-Threshold InGaAs/InGaAsP Multiple Quantum Well Lasers Grown by Chemical Beam Epitaxy
Authors: Yamada Takeshi , Iga Ryuzo , Yoshio Noguchi Yoshio Noguchi , Hideo Sugiura Hideo Sugiura
Published: February 2005

InGaAs/InGaAsP separate confinement heterostructure (SCH) multiple quantum well (MQW) lasers were successfully fabricated using chemical beam epitaxy (CBE) with a pressure-control system of gaseous sources. Grown films were processed into double-channel planar buried heterostructure (DCPBH) lasers of 1.5-µm stripe width with regrowth by liquid-phase epitaxy. The uncoated lasers were 300 µm long, and exhibited cw operation with a threshold current as low as 12 mA. About 90% of the lasers had a threshold current below 16 mA. The slope efficiency was 0.22 mW/mA and the characteristic temperature T
0 was 60 K. The uniformity of the grown films and photoluminescence of the MQWs were also studied.
Synchrotron Radiation-Assisted Removal of Oxygen and Carbon Contaminants from a Silicon Surface
Authors: Nara Yasuo , Sugita Yoshihiro , Noriaki Nakayama Noriaki Nakayama , Takashi Ito Takashi Ito
Published: February 2005

A silicon dioxide film was etched by synchrotron radiation (SR) irradiation at a substrate temperature of about 500°C. The obtained etching rate was 13 nm/h and the activation energy approximately 1.2 eV. This process was applied to remove surface contaminants on a silicon surface. Oxygen and carbon contaminants in the SR-irradiated area decreased by about 1/3 and 1/10, respectively, indicating that SR irradiation is effective for surface cleaning. A sharp peak in Raman spectrum appeared when a silicon film was deposited after SR irradiation. Thus, the pre-irradiation by SR improves the crystal quality of the deposited film.
Selective-Area-Grown AlGaAs/GaAs Single Quantum Well Lasers on Si Substrates by Metalorganic Chemical Vapor Deposition
Authors: Kobayashi Yasufumi , Egawa Takashi , Takashi Jimbo Takashi Jimbo , Masayoshi Umeno Masayoshi Umeno
Published: February 2005

High-quality GaAs layers with dislocation densities of less than 5×106 cm-2 on Si substrates have been obtained through a combination of thermal-cycle annealing and selective-area growth using the metalorganic chemical vapor deposition method. The Al0.3Ga0.7As/GaAs single quantum well laser grown on a Si substrate by means of these techniques has a pulsed threshold current of 165 mA (3.92 kA/cm2) at 300 K and a CW threshold current of 152 mA (4.78 kA/cm2) at 200 K. Stacking faults or microtwins near the boundary of the SiO2 mask are thought to cause a pulsed operation at 300 K for the selective-area-grown laser.
Modulation Spectroscopies on a GaAs/InAs/GaAs Single-Monolayer Structure
Authors: Castrillo Pedro , Armelles Gaspar , Ana Ruiz Ana Ruiz , Fernando Briones Fernando Briones
Published: February 2005

Piezoreflectance, photoreflectance and reflectivity measurements have been performed on a sample consisting of one InAs monomolecular plane in bulklike GaAs grown by atomic layer molecular beam epitaxy. The heavy-hole and light-hole characteristics of the two excitonic InAs-related transitions observed are experimentally elucidated for the first time. The electric field modulation observed in the photoreflectance spectra of such a heterostrvcture cannot be attributed to the quantum-confined Stark effect.
A Small Collector-Up AlGaAs/GaAs Heterojunction Bipolar Transistor Fabricated Using H+ Implantation
Authors: Hirose Takashi , Akira Ryoji Akira Ryoji , Masanori Inada Masanori Inada
Published: February 2005

A small collector-up AlGaAs/GaAs heterojunction bipolar transistor with a collector size of 1×10 µm2 is developed by making the entire emitter layer under the external base highly resistive by oblique H+ implantation from both sides along the elongated direction of the collector mesa, and by forming the collector electrode and base electrodes by self-alignment method. The transistor shows high-frequency properties of f
T=31 GHz and f
max=50 GHz. The relationship between the process used and the properties of the transistor is analyzed.
High-Pressure Synthesis of Superconducting La1.7Ca1.3Cu2Oy
Authors: Bin Okai Bin Okai
Published: February 2005

At a high pressure of 6 GPa, La1.7Ca1.3Cu2O
y
and La1.7Sr1.3Cu2O
y
of the Sr3Ti2O7 structure were synthesized. A supply of oxygen was necessary for the synthesis of La1.7Ca1.3Cu2O
y
, while La1.7Sr1.3Cu2O
y
became multiphased under high oxygen pressure. The compound La1.7Ca1.3Cu2O
y
was a superconductor with the onset temperature of 70 K. With further increase of oxygen for synthesis, La1.7Ca1.3Cu2O
y
changed structure, and the onset temperature became 75 K.
Magnetization of Ceramic Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O after Neutron Irradiation
Authors: Takamura Saburo , Sekino Hajime , Matushima Hideo , Kobiyama Mamoru , Hoshiya Taiji , Sumiya Keiji , Kuwajima Hideji
Published: February 2005

Magnetization of ceramic Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O superconductors was studied after neutron irradiation in the fluence from 2.4×1021/m2 to 1.8×1022/m2 at 60°C. The area of hysteresis loops was enhanced at low neutron fluence, followed by saturation and then a decrease at high fluence. In Bi-Sr-Ca-Cu-O, the degree of enhancement was smaller than in Y-Ba-Cu-O and the enhancement reached saturation at lower neutron fluence.
Frequency Stabilization of a Dye Laser to a Reference Cavity with Sub-Hertz Relative Linewidth
Authors: Kazuhiko Sugiyama Kazuhiko Sugiyama , Atsuo Morinaga Atsuo Morinaga
Published: February 2005

We reduced the frequency fluctuation of a cw single frequency dye laser to the shot-noise limit at the Fourier frequency between 7 kHz and 20 kHz by the phase modulation technique. From the spectral density and the distribution of the instantaneous amplitude of the error signal, the relative linewidth of a dye laser to the reference cavity was estimated to be sub-Hz.
High-Resolution Holography Observation of H-Nb2O5
Authors: Kawasaki Takeshi , Ru Qing Xin , Matsuda Tsuyoshi , Bando Yoshio , Akira Tonomura Akira Tonomura
Published: February 2005

Electron holograms of H-Nb2O5 are formed from about 150 diffracted waves used to reconstruct high-resolution images. A niobium atom arrangement in H-Nb2O5 is observed in an aberration-corrected phase image. A hologram with 9.3-pm carrier fringes is also formed. It is the finest carrier fringe spacing hologram ever reported.
Deep Levels Associated with Molybdenum in Silicon
Authors: Toshiaki Hamaguchi Toshiaki Hamaguchi , Yoshinori Hayamizu Yoshinori Hayamizu
Published: February 2005

The behavior of Mo in Si has been investigated to identify energy levels associated with Mo and to confirm the effect on electrical properties of Si using DLTS, optical-DLTS and the minority carrier recombination lifetime measurement. Four deep levels at E
c-0.27, E
c-0.34, E
c-0.58 and E
v+0.31 eV were determined as Mo-related deep levels. It is confirmed that levels at E
c-0.27, E
c-0.34 and E
v+0.31 eV are not due to the complex of Mo and a dopant. Mo degrades the minority carrier recombination lifetime. The diffusion coefficient of Mo is determined to be 2×10-10 cm2/s at 1000°C.
Superconducting Current Density Profiles Estimated from the Flux Density Distribution in YBa2Cu3Ox Thin Films
Authors: Yokoyama Yuko , Suzuki Yoshishige , Hasumi Yuichi , Obara Haruhiko , Yosimi Takashi , Kita Yasuyo , Shin Kosaka Shin Kosaka , Sadafumi Yoshida Sadafumi Yoshida
Published: February 2005

The flux penetration in superconducting thin films has been observed by means of the magnetooptical Faraday effect in iron garnet films. Bi- and Ga-substituted YIG films were used for the observation of the flux density distribution for the disk-shaped YBa2Cu3O
x
films with a radius of 0.5 mm and a thickness of 1800 Å. Critical current density J
c was estimated from the whole profile of the flux density distribution without using Bean's model. The estimated J
c is about 6×106 A/cm2 at 10 K, and this value is smaller than that estimated using Bean's model from the remanent magnetization at the same temperature.
Actively and Passively Mode-Locked Nd:YAP(YAlO3) Laser with Negative Feedback Using CdSe and GaAs
Authors: Kubecek Vaclav , Kumazaki Shigeichi , Takagi Yoshihiro , Reali Giancarlo C. , Keitaro Yoshihara Keitaro Yoshihara
Published: February 2005

The feedback-controlled mode-locking operation of a flash-lamp-pumped Nd: YAP(YAlO3) laser using a CdSe passive element is reported for the first time. Pulse trains with a duration of 1000 ns, single pulse width of 5 ps and pulse energy of 10 µJ are generated. The performances of CdSe and GaAs negative feedback elements are compared.