bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selenium Doping in GaAs Grown by Molecular Beam Epitaxy
Authors: Eriko T. Sano Eriko T. Sano , Yoshiji Horikoshi Yoshiji Horikoshi 
Published: October 2002

Using elementary Se as n-type dopant,
Se-doped GaAs films were grown by molecular beam epitaxy.
Characteristics of the films can be classified
according to the amount of Se doped into areas where
carrier concentration
increases linearly [area I]
(Se concentration ≤4 ×1018 cm-3),
saturates [area II] ( 4 ×1018–1 ×1020 cm-3)
and decreases [area III] ( ≥1 ×1020 cm-3).
In each area, we found a close correlation between
electrical activity and photoluminescence spectra.
The activation ratio of Se donors was found to be high
in the samples classified in area I.
These samples showed an efficient photoluminescence,
although the observed spectra included deep level emissions
at 890 nm and 1050 nm in addition to the band-edge
excitonic emission.
For the samples in areas II and III, however,
photoluminescence efficiency dropped considerably
and only a broad band emission (1300–1500 nm)
appeared.
This broad band emission is probably caused by
complexes that include Ga
vacancies and Se atoms because
distinct electron concentration saturation takes place
in this region.
Electron Energy-Loss Spectra of Single-Shell Carbon Nanotubes
Authors: Kuzuo Ryuichi , Terauchi Masami , Saito Michiyoshi Tanaka 
Published: October 2002

Transmission electron energy-loss spectra of single-shell carbon nanotubes were measured and compared with those of multishell carbon nanotubes and graphite. Two peaks due to the π plasmon and the π+σ plasmon were observed at 5.8 eV and 20.6 eV, respectively. The energy of the π plasmon takes a value between those of two kinds of multishell tubes. The energy of the π+σ plasmon is lower than those of multishell tubes and graphite by 2 eV and 6 eV, respectively. The 1s→π* and 1s→σ* transition peaks of the single-shell tubes are much broader than those of the multishell tubes and graphite. The reason for the broadening may be due to the strong curving of the graphitic sheets.
Radiolysis of Solid CO2 and Future Electron Spin Resonance Dating on Outer Planets
Authors: Makoto Hirai Makoto Hirai , Motoji Ikeya Motoji Ikeya , Yoshiaki Tsukamoto Yoshiaki Tsukamoto , Chihiro Yamanaka Chihiro Yamanaka 
Published: October 2002

Paramagnetic radicals have been detected in solid CO2 with gamma irradiation at 77 K
with the measurement of electron spin resonance (ESR). Species of O3
-,
CO3
-, CH3, SO3
- and HO2 are identified. The lifetimes of
O3
-, CH3 and HO2 at several temperatures were obtained by isothermal
annealing experiments. Their stability at the ambient temperature of Mars and icy
satellites was estimated from the Arrhenius plot of the lifetime for the future
possibility of ESR dating of solid CO2.
Low-Temperature Chemical Vapor Deposition of Silicon Dioxide Using Tetra-isocyanate-silane (Si(NCO)4)
Authors: Hitoshi Taniguchi Hitoshi Taniguchi , Osamu Sugiura Osamu Sugiura 
Published: October 2002

Deposition characteristics and step coverage of low-temperature
chemical vapor deposition
silicon dioxide (CVD SiO2) using tetra-isocyanate-silane
( Si(NCO)4; TICS) and H2O
have been investigated for application to interlayer
dielectric films for advanced VLSI.
The deposition rate was 13 nm/min at 100°C.
The rate rapidly decreased with the
increasing deposition temperature.
It was determined by partial pressure rather than
by flow rate of material gases.
The step coverage showed a conformal profile.
Open-Base Multi-Emitter HBTs with Increased Logic Functions
Authors: Imamura Kenichi , Takatsu Motomu , Mori Toshihiko , Muto Shunichi , Naoki Yokoyama Naoki Yokoyama 
Published: October 2002

We have designed and tested a new functional device, an open-base multi-emitter heterojunction bipolar transistor (ME-HBT) which operates at room temperature. In this paper, we discuss the dependence of emitter doping concentration on the DC characteristcs of the ME-HBTs. The collector current turn-on volatge decreases to 0.7 V with an emitter doping of 1×1019 cm-3.
Using a ME-HBT, we constructed a 3-input AND/NOR gate, and confirmed that operation at room temperature was normal using an operating voltage of 2 V.
We also discuss a problem with this ME-HBT circuit and offer a possible solution. We believe our approoach will prove useful for various ICs due to its simplicity and functionality.
Sonochemical Oxidation of Iodide Ions in Solution Undersaturated with Ambient Gases
Authors: Hiroyuki Kitano Hiroyuki Kitano , Shigeo Hayashi Shigeo Hayashi 
Published: October 2002

Sonochemical oxidation of I3
- has been carried out in atmospheres of nitrogen, oxygen, air, and argon in the pressure range between 40 Torr and 760 Torr. The ambient gases have been dissolved by two methods: distillation and bubbling, with the former leading to undersaturation. Except for nitrogen, no simple relation exists between the reaction rates for the gas-undersaturated solutions, k
U, and those for the gas-saturated solutions, k
S. In some cases the values of k
U are five times greater than those of k
S in spite of the reversed order in the gas concentration.
Photoacoustic Spectra of Si Wafers at Liquid Helium Temperature
Authors: Hiroyuki Matsuyama Hiroyuki Matsuyama , Tetsuo Ikari Tetsuo Ikari , Hirosumi Yokoyama Hirosumi Yokoyama , Koji Futagami Koji Futagami 
Published: October 2002

Photoacoustic (PA) measurements of p- and n-type Si single crystals are carried out at liquid helium temperature (4.2 K). Two small peaks around 1.2 eV are observed in both samples. The energy of the higher-energy peak at 1.21 eV agrees with the thresholds of free exciton absorption with the emission of TO momentum-conserving phonons. The lower-energy peak shifts to the higher energy side with the decrease of the excitation light intensity. The possibility of the formation of an electron-hole drop for the lower energy peak will be discussed to explain the experimental results.
Green Photoluminescence from \mbα-Phase ZnAl 2S 4
Authors: Tetsuya Kai Tetsuya Kai , Masakazu Kaifuku Masakazu Kaifuku , Igor Aksenov Igor Aksenov , Katsuaki Sato Katsuaki Sato 
Published: October 2002

A bright green photoluminescence with a peak at 540 nm was observed at low temperature in the α-phase ZnAl2S4 ternary compound grown by heating ZnS, Al and S powders. The emission is interpreted as arising from donor-acceptor(DA)-pair recombination. At room temperature the green emission is dominated by two weak emission bands in the infrared spectral region.
Evaluation of Optical Glasses for Low-Loss Fibers: Optical Attenuation and Fiber Drawing Ability
Authors: Todoroki Shin-ichi , Shigeki Sakaguchi Shigeki Sakaguchi , Kiyomasa Sugii Kiyomasa Sugii 
Published: October 2002

Optical attenuation of commercial optical glasses with low refractive indices is evaluated on the basis of the measurements for light scattering and infrared absorption. Furthermore, these glasses are drawn into fibers to examine the stability against crystallization in the fiber drawing process. All glasses exhibit light scattering intensity higher than that of silica glass. Fluorophosphate glasses are crystallized during fiber drawing. The present evaluation reveals that silicate glass, C7, is suited for low-loss fibers. The intrinsic minimum attenuation is predicted to be 0.8 dB/km at 1.2 µm, which is somewhat larger than that of silica glass. In addition, the estimations for density and concentration fluctuations indicate that concentration fluctuation dominates the light scattering in multicomponent optical glass.
Investigations of Electronic Structures of Defects Introduced by Ar Ion Bombardments on MoS 2 by Scanning Tunneling Microscopy
Authors: Naohisa Sengoku Naohisa Sengoku , Keiichi Ogawa Keiichi Ogawa 
Published: October 2002

We have investigated the defects introduced by Ar ion bombardment on cleaved MoS2 surface by scanning tunneling microscopy (STM). The resultant defects have been observed at room temperature as dark regions typically 6–8 nm in diameter and their contrast is found to depend on the sample bias voltage (SB). The high-temperature STM observations at 600°C and 800°C show a reduction of the diameter to 2–4 nm. Based on these experimental results it is concluded that the S atom complex produced at the defect site is partially negatively ionized and a depletion region of conduction electrons is produced around it. The observed lateral extent of the depletion region is in good agreement with that calculated from the repulsive Coulomb potential due to the negatively charged complex. The calculated screening length, however, disagrees with the observed size of the dark region.
Improvement of Kelvin Probe Force Microscope (KFM) System
Authors: Masatoshi Yasutake Masatoshi Yasutake 
Published: October 2002

The Kelvin probe force microscope (KFM) is a useful tool that measures the surface potentials of both conducting and nonconducting materials. Recently, we have succeeded in improving the accuracy of potential measurements and increased the lateral resolution of the topographic image. Furthermore, Z axis servo control was improved to prevent the tip from coming into contact with the sample surface during scanning. Finally, the force gradient between the tip and the sample became steeper during the acquisition of the topographic image due to the inactivation of the modulation AC voltage. As a result, the potential resolution was less than 1 mV and the lateral resolution of the topographic image was improved to as high as 10 nm.
Disappearance of the Breakdown of Quantum Hall Effects in Short Devices
Authors: Yasushi Kawaguchi Yasushi Kawaguchi , Fumio Hayashi Fumio Hayashi , Susumu Komiyama Susumu Komiyama , Toshihito Osada Toshihito Osada , Yasuhiro Shiraki Yasuhiro Shiraki , Ryoichi Itoh Ryoichi Itoh 
Published: October 2002

Device-length dependence of the breakdown of the integer quantum Hall effects is studied by using devices with narrow constricted regions of different lengthsLatT=1.5 – 4.2 K and Landau-level filling factors of ν= 2, 4 and 6. Samples are fabricated from GaAs/AlGaAs heterostructures. Sharp increase in the diagonal resistanceRxat a critical current disappears, and is replaced by a continuous and gradual increase in short constricted regions ofL< 30 µm. The observedL-dependence supports an avalanche-type carrier multiplication mechanism triggered by electron-superheating.
Anomalous Magnetoresistance near Superconducting Transition Temperature in a Mesoscopic Aluminum Wire
Authors: Seongjae Lee Seongjae Lee , Kyoung Wan Park Kyoung Wan Park , Mincheol Shin Mincheol Shin , El-Hang Lee El-Hang Lee , Hyuk Chan Kwon Hyuk Chan Kwon 
Published: October 2002

We have observed an anomalous magnetoresistance (MR) in a mesoscopic aluminum wire near the superconducting transition temperature. The anomaly exists in a region of low magnetic field less than 12.5 G and within the narrow temperature region where the Ginzburg-Landau coherence length exceeds half the distance between the voltage probes. It consists of a “mesa” or “peak”-type MR centered around zero field (negative MR) with zero resistance outside the field region; in other words, the sample undergoes a normal-superconducting-normal transition as the magnetic field increases. Satellite peaks around the mesa MR were also observed for a very narrow range of temperature. We speculate that the sample size and dimensionality play an important role in these phenomena, but the origin is unclear.
Formation of InGaAs Quantum Dots on GaAs Multi-Atomic Steps by Metalorganic Chemical Vapor Deposition Growth
Authors: Masatoshi Kitamura Masatoshi Kitamura , Masao Nishioka Masao Nishioka , John Oshinowo John Oshinowo , Yasuhiko Arakawa Yasuhiko Arakawa 
Published: October 2002

Aligned InGaAs quantum dots as small as 20 nm were naturally formed at multi-atomic step edges by metalorganic chemical vapor deposition growth. In addition, it was found that anisotropic structure of InGaAs along the step edges toward the [110]A direction appears with the increase of growth time of InGaAs. This phenomenon may be useful in the formation of quantum wires.
Many-Body Effects in the Magnetoplasma of In 0.13Ga 0.87As/GaAs Quantum Wires
Authors: Forchel Manfred Bayer , Stefan Benner Stefan Benner , Hartmut Haug Hartmut Haug 
Published: October 2002

We have performed photoluminescence experiments on modulated barrier In0.13Ga0.87As/GaAs quantum wires in normal magnetic fields up to B = 10.5 T. By using high excitation powers we observed emission from several lateral subbands. In comparison to low excitation spectra the emission features are shifted to lower energies due to band gap renormalization. Calculated luminescence spectra are in excellent agreement with the experimental spectra and have been used to study many-particle effects in these wires. We have found clear indications for an enhancement of the renormalization in quantum wires as expected due to the increase of the Coulomb interaction.
One-Dimensional Quantum Electron and Hole States in n-AlxGa 1-xAs/u-GaAs/u-AlxGa 1-xAs Corrugated Double-Heterojunctions
Authors: Karel Vacek Karel Vacek , Toshiyuki Usagawa Toshiyuki Usagawa 
Published: October 2002

Quasi-one-dimensional quantum electron and hole states are suggested in modulation-doped n-AlxGa1-x
As/u-GaAs/u-AlxGa1-x
As corrugated double heterojunctions. The interfaces between n-AlxGa1-x
As/u-GaAs and u-GaAs/u-AlxGa1-x
As are saw-tooth corrugated by bends with period 850 Å and bending angle 90°. The thickness of the sandwiched GaAs layer is 150 Å. Quantum-mechanical simulations are performed for electrons and holes. The electrons are found to be densely packed in quasi-one-dimensional states located in the convex corner of the GaAs layer near the doped layer of n-AlxGa1-x
As. The hole states are also quasi-one-dimensional and are located in the convex corner of the GaAs layer near the undoped layer of u-AlxGa1-x
As. Consequently, spatial separation of ground level electron and hole quantum states can be achieved.
Silicon-Based Single-Electron-Tunneling Transistor Operated at 4.2 K
Authors: Akiko Ohata Akiko Ohata , Hiromi Niiyama Hiromi Niiyama , Toru Shibata Toru Shibata , Kazuaki Nakajima Kazuaki Nakajima , Akira Toriumi Akira Toriumi 
Published: October 2002

We have fabricated single-electron-tunneling transistors using	silicon which is a useful material	for device applications.	The device is composed of thin polycrystalline silicon	film patterned	by electron-beam lithography and its thermally	grown oxidized film.	We have observed, in this device,	periodic conductance oscillations as a function	of gate voltage and nonlinear resistances	as a function of drain voltage at 4.2 K.	These experimental results are in agreement	with the theory of Coulomb blockade.	We conclude that the observed behavior	results from the charging energy	of single-electron tunneling.
Study of Inelastic Scattering Effect in Unstrained and Strain-Compensated GaInAs/GaInP Multiquantum Barriers
Authors: Terhoe Loh Terhoe Loh , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga , Kazuhito Furuya Kazuhito Furuya 
Published: October 2002

The effect of inelastic scattering on electron reflection in multiquantum barriers has been examined for the first time by using the damped resonant tunneling model. The electron reflectivity exhibits marked deterioration to values below unity at discrete energies in the virtual barrier. The largest dip in reflectivity is about 15% for an intraband relaxation time of 0.16 ps. It is also shown that this deterioration can be reduced by utilizing a strain-compensated superlattice in the multiquantum barriers.
Microwave Dielectric Properties of the Ba6-3x(Sm 1-y,\mbRy) 8+2xTi 18O 54 (\mbR=Nd and La) Solid Solutions with Zero Temperature Coefficient of the Resonant Frequency
Authors: Hitoshi Ohsato Hitoshi Ohsato , Hiromichi Kato Hiromichi Kato , Makoto Mizuta Makoto Mizuta , Susumu Nishigaki Susumu Nishigaki , Takashi Okuda Takashi Okuda 
Published: October 2002

Ba6-3x
(Sm1-y
,R

y
)8+2x
Ti18O54 (R = Nd and La; x = 0.6, 0.0 ≤y ≤1.0) solid solutions in which Nd or La ions are substituted for Sm ions were studied from the point of microwave dielectric materials. In both Sm-Nd and Sm-La series, formation of solid solutions was found, which was deduced from linear change of the lattice parameters. We found high-quality resonator materials in the both series which show high ε
r of 84, Q· f products of 9000 GHz, and temperature coefficient of resonance frequency τ f=0 ppm/\CC. The compositions of those materials in the Sm-Nd and the Sm-La series were determined to be y = 0.2 and 0.1, respectively. A relationship between dielectric constant and volume of octahedron is also stated.
Dielectric Relaxation Modes in the Phases of Antiferroelectric Liquid Crystals
Authors: Hiroyuki Uehara Hiroyuki Uehara , Yoshihiro Hanakai Yoshihiro Hanakai , Jun Hatano Jun Hatano , Shin'ichi Saito Shin'ichi Saito , Katsuyuki Murashiro Katsuyuki Murashiro 
Published: October 2002

Complex dielectric constant of an antiferroelectric liquid crystal family represented by 4-(1-methylheptyloxycarbonyl) 3-fluorophenyl 4'-dodecylbiphenyl-4-carboxylate was measured in the frequency range between 10-2 Hz and 107 Hz. The experimental results were analyzed using a generalized Cole-Cole expression, and seven dielectric relaxation modes were confirmed to exist. Possible models of collective molecular motions are proposed for mode assignments on the basis of the experimental results of temperature dependence of the modes, together with those of cell gap and bias field dependences.
Electron Beam Calibration Method for Character Projection Exposure System EX-8D
Authors: Hitoshi Sunaoshi Hitoshi Sunaoshi , Kiyoshi Hattori Kiyoshi Hattori , Jun Takamatsu Jun Takamatsu , Atsushi Ando Atsushi Ando , Hirotsugu Wada Hirotsugu Wada , Shunko Magoshi Shunko Magoshi , Toshio Yamaguchi Toshio Yamaguchi , Shinji Sato Shinji Sato , Shinsuke Nishimura Shinsuke Nishimura , Hiroaki Housai Hiroaki Housai , Susumu Hashimoto Susumu Hashimoto , Ryouichi Yoshikawa Ryouichi Yoshikawa , Tadahiro Takigawa Tadahiro Takigawa 
Published: October 2002

A character beam calibration method has been developed for the electron beam exposure system EX-8D. The method concerns the character selection deflector, beam current density uniformity, beam size, direction, and position on the target.	For the current density, the uniformity of less than 1.4 has been obtained in a 2-mm-square field. The beam size and the direction has been calibrated with an error of less than 1 nm in a 1-µm-square character beam.	The overall error of the resist pattern size exposed by the character beam was estimated to be 7.2 nm. For the beam position on the target, the calibration accuracy of 0.023 µm has been obtained by a pattern matching method.	After applying the calibration, 0.15 µm line-and-space patterns were exposed with good resolution by using the character beam. Also, a test pattern has been written with 0.02 µm stitching accuracy between variable shaped and character beams.
Numerical Prediction for 2 GHz RF Amplifier of SOI Power MOSFET
Authors: Ichiro Omura Ichiro Omura , Akio Nakagawa Akio Nakagawa 
Published: October 2002

RF performance of a metal-oxide-semiconductor field effect transistor (MOSFET) on silicon-on-insulator (SOI) with 0.5 µm gate length and 2 µm buried oxide thickness has been numerically predicted using a 2-D device simulator to check its applicability to digital cellular telephones. The device has been found to have excellent performance for a 2 GHz high-power amplifier at a power supply of 2.8 V. The calculated cutoff frequency and maximum frequency of oscillation for the intrinsic MOSFET are 23 GHz and 65 GHz, respectively. The SOI MOSFET is a promising candidate for replacing GaAs MESFETs in 2 GHz RF applications.
Determination of the Conduction Band Electron Effective Mass in Hexagonal GaN
Authors: M. Drechsler M. Drechsler , D. M. Hofmann D. M. Hofmann , B. K. Meyer B. K. Meyer , T. Detchprohm T. Detchprohm , H. Amano H. Amano , I. Akasaki I. Akasaki 
Published: October 2002

The electron effective mass in hexagonal GaN films grown by metal organic vapor phase epitaxy on sapphire substrates is determined by cyclotron resonance experiments. Its value is m
p
* = 0.22±0.005 m
o. Taking polaron effects into account the band edge mass is m
b
* = 0.20±0.005 m
o. From the resonance linewidth a mobility of 3500 cm2/V·s at 6 K is obtained.
Large Electro-Optical Modulation of a Field-Effect Transistor-Type Waveguide Modulator Using α-Sexithienyl
Authors: Tetsuyuki Kurata Tetsuyuki Kurata , Chie Fukada Chie Fukada , Hiroyuki Fuchigami Hiroyuki Fuchigami , Kouji Hamano Kouji Hamano , Sei Tsunoda Sei Tsunoda 
Published: October 2002

An optical waveguide modulator having a field-effect transistor-type electrode using a thiophene oligomer, α-sexithienyl, has been fabricated and has functioned as an electro-absorption modulator with the modulation ratio of 20%. The device also functions as a field-effect transistor (FET). The optical modulation is directly related with the FET device operation, and has shown a maximum at 830 nm for propagating light wavelength. Therefore, the mechanism of the optical modulation has been clarified to be the increasing absorption due to polarons induced or injected by negative bias.
Surface Oxidation Behavior of TiN Film Caused by Depositing SrTiO 3 Film
Authors: Yanagisawa Yoshio Abe , Katsutaka Sasaki Katsutaka Sasaki 
Published: October 2002

TiN thin films are prepared by rf magnetron sputtering in order to examine their applicability as bottom electrodes of dynamic random access memory (DRAM) capacitors. On the TiN thin films, SrTiO3 thin films are deposited in various O2/(Ar+O2) sputtering gas flow ratios and substrate temperatures, and the amount of TiN which is converted to oxide during SrTiO3 deposition is evaluated from the change in its resistance. Thickness of the oxidized TiN was reduced from 43 nm to 7 nm by decreasing the O2 flow ratio from 100% to 0% and decreasing the substrate temperature from 400°C to 300°C during SrTiO3 deposition. The applicability of the TiN thin film as a bottom electrode of DRAM capacitors is discussed.
Metalorganic MBE Growth of Nitrogen-doped ZnSe: TAN Doping and Nitrogen Plasma Doping
Authors: Go Sato Go Sato , Takahiro Numai Takahiro Numai , Mitsuo Hoshiyama Mitsuo Hoshiyama , Ikuo Suemune Ikuo Suemune , Hideaki Machida Hideaki Machida , Norio Shimoyama Norio Shimoyama 
Published: October 2002

Growth of ZnSe and nitrogen doping were carried out by metalorganic molecular beam epitaxy (MOMBE). In this study metalorganic precursors were introduced into the growth chamber directly without precracking. We studied two nitrogen doping techniques. First, doping with the nitrogen precursor triallylamine (TAN) was studied. It was found that TAN decomposes above 300°C by quadrupole mass spectrometry. The doping properties of TAN were critically dependent on the VI/II ratio during growth. However contrary to our expectation, the doped ZnSe films tended to be n-type. The other nitrogen-doping technique involves doping with nitrogen gas activated by an electron cyclotron resonance plasma. In the samples doped with the nitrogen plasma, donor-acceptor pair emission was dominant. The net acceptor concentration up to 2.3×1017 cm-3 was measured in samples grown using this doping technique.