bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of recorded magnetization pattern by electron holography
Authors: Osakabe Nobuyuki , Yoshida Kazuetsu , Horiuchi Yasuaki , Matsuda Tsuyoshi , Tanabe Hideo , Okuwaki Toyoji , Endo Junji , Fujiwara Hideo , Tonomura Akira
Published: February 2003

Electron holography was employed for experiments involving a high-density magnetic recording, in which it was possible to directly observe streams of magnetic flux. The magnetic flux distribution in recorded films, and the maximum packing density in high-coercivity evaporated cobalt film were investigated. With magnetic longitudinal recording the resultant highest density was 170 000 bits per inch. This experiment has proven that electron holography is useful for the study of magnetic recording.
Inverse Lamb dip spectroscopy using microwave modulation sidebands of CO2 laser lines
Authors: Magerl Gottfried , Frye Joan M. , Kreiner Welf A. , Oka Takeshi
Published: February 2003

We report the observation of infrared Lamb dips using a widely tunable laser source. The microwave sidebands generated on CO2 laser lines provide sufficient power (∼0.5 mW) and spectral purity (Δν≲100 kHz) for saturation spectroscopy. Application of this infrared source to the observation of infrared Lamb dip spectra of CH3F and SiF4 is reported.
Temperature dependence of liquid crystal tilt angles
Authors: van Sprang H. A. , Aartsen R. G.
Published: February 2003

In a homogeneous cell the origin of the steep decrease, which is always observed in the liquid crystal tilt angle on an SiO coating as a function of temperature in the range close to Tc, is traced back to the growth of twist domains. It appears that a magnetic null method is unsuited for accurate tilt angle measurements in the relevant temperature region, because it is based on the assumption of a homogeneous director pattern in the sample cell.
Optical and electrical properties of amorphous silicon films prepared by photochemical vapor deposition
Authors: Saitoh T. , Muramatsu S. , Shimada T. , Migitaka M.
Published: February 2003

Amorphous silicon films have been prepared through mercury-photosensitized decomposition of monosilane gas at low temperatures. The films show optical and electrical properties comparable with those of the best films prepared by plasma chemical vapor deposition. The feasibility of amorphous solar cells with short-circuit current densities of more than 10 mA/cm2 has been demonstrated by fabrication of a Schottky barrier structure.
Evidence that the gold donor and acceptor in silicon are two levels of the same defect
Authors: Ledebo L-Å. , Wang Zhan-Guo
Published: February 2003

A photocapacitance method was used to monitor the time dependences of the occupation numbers for the gold-related donor and acceptor in silicon during optical excitation. The experimental data give strong evidence that the donor level corresponds to the +/0 transition and the acceptor to the 0/− transition for one single defect.
Picosecond AlxGa1−xAs modulation-doped optical field-effect transistor sampling gate
Authors: Bethea C. G. , Chen C. Y. , Cho A. Y. , Garbinski P. A. , Levine B. F.
Published: February 2003

New modulation-doped Alx Ga1−xAs/GaAs metal-semiconductor field-effect photodetectors have been fabricated and tested in a novel picosecond optical sampling gate configuration. The rise time was measured to be 12 ps, with a full width at half-maximum of 27 ps. The optical electronic picosecond cross-correlation measurement has shown the importance of the two-dimensional electron gas for high-speed operation.
Gettering of oxygen in Si wafers damaged by ion implantation and mechanical abrasion
Authors: Mikkelsen J. C.
Published: February 2003

Isotopic substitution of 18O was used in conjunction with secondary ion mass spectrometry to distinguish the source of gettered oxygen associated with damage produced in Si wafers by As ion implantation and by mechanical abrasion. It was found that oxygen was gettered from annealing ambients, exhibiting an enhanced diffusivity in the vicinity of the damaged layers at 600 °C. On the contrary, the oxygen originally dissolved in the wafers was unaffected by the damage, not being gettered by either type of damage and having the same diffusivity at that in undamaged Si crystals. These results are compared with published reports of 16O analysis of similar experiments.
Blocking oscillation of optical bistable devices using dc drift phenomena of LiNbO3 waveguide
Authors: Yumoto J. , Yajima H. , Ishihara S. , Sekiguchi Y. , Yamaya K. , Nakajima M.
Published: February 2003

Graphical solutions and experimental results of the blocking oscillation of the guided-wave optical bistable devices using dc drift phenomena of LiNbO3 are reported. The frequency of the oscillation can be varied in the range from 0.1 to 100 Hz by changing biasing voltage and input light level.
Passive mode locking of buried heterostructure lasers with nonuniform current injection
Authors: Harder Christoph , Smith John S. , Lau Kam Y. , Yariv Amnon
Published: February 2003

In this letter we report on a novel method to passively mode lock a semiconductor laser. We present experimental results of GaAlAs buried heterostructure semiconductor laser with a split contact coupled to an external cavity. The split contact structure is used to introduce a controllable amount of saturable absorption which is necessary to initiate passive mode locking. Unlike previous passive mode locking techniques, the method presented does not rely on absorption introduced by damaging the crystal and is consequently inherently more reliable. We have obtained pulses with a full width at half-maximum of 35 ps at repetition frequencies between 500 MHz and 1.5 GHz.
Enhanced HgBr(B2Σ+→X 2Σ+) emission at low pressures
Authors: Lapatovich Walter P. , Gibbs George R. , Proud Joseph M.
Published: February 2003

Additives of N2 and I2 vapor in diffuse HgBr2 discharges have been observed to produce a large enhancement of radiated power due to B2Σ+→X2Σ+ transitions at low pressures. The integrated power in the spectral range between 374 and 543 nm was recorded by means of an optical multichannel analyzer system. Optimization of the B→X radiation was investigated, and absolute efficiency was determined over a range of ‖E‖/N.
Current-assisted laser annealing of polysilicon films
Authors: Okamoto K. , Suzunaga H.
Published: February 2003

In this letter we suggest the current-assisted laser annealing of polysilicon films deposited on SiO2 by chemical vapor deposition of silane. QA-switched ruby laser was irradiated to polysilicon films with applying an electric field. Then, a large photocurrent flowed through the films during the laser irradiation, and the resistivity of the polysilicon films decreased drastically from ∼108 to ∼104 Ω cm by the current-assisted laser annealing, while the resistivity decreased only to ∼106 Ω cm in the case of the conventional laser annealing (zero electric field). The effects of the applied electric field on the annealing are due to the local heating at the grain boundaries and the promotion of the coalescence among the grains.
Temperature dependence of interface recombination and radiative recombination in (Al, Ga)As heterostructures
Authors: ’t Hooft G. W. , van Opdorp C.
Published: February 2003

From measurements of the quantum efficiency of Al0.12Ga0.88As-Al0.47Ga0.53As double heterostructures the effective nonradiative carrier lifetime in the active region and at its interfaces is determined. From the dependence of this lifetime on active layer thickness a value for the interface recombination velocity s is obtained. For a particular sample grown by liquid phase epitaxy s turned out to be 1050 cm/s at 300 K; between 110 and 360 K the interface recombination velocity is proportional to exp(−Ea/kT) with an activation energy Ea of 27 meV. In the analysis the radiative coefficient B is taken to be proportional to T−1.5, as theory predicts when a k-selection rule holds. This behavior of B was verified experimentally with temperature-dependent minority-carrier lifetime measurements.
Laser plasma coupling in long pulse, long scale length plasmas
Authors: Campbell E. M. , Rosen M. D. , Phillion D. W. , Price R. H. , Estabrook K. , Lasinski B. F. , Obenschain S. P. , Mclean E. A. , Whitlock R. R. , Ripin B. H.
Published: February 2003

Laser plasma coupling under near reactor-size target conditions is studied at Iλ2≂1014 W/cm2 μm2 with 1-mm size plasmas, 3-kJ, 3-ns irradiations on the 1.064-μm Shiva laser. Evidence for the occurrence of parametric processes, such as stimulated Brillouin sidescatter and the two-plasmon decay instability, is observed.
Cross section for photoelectron capture by IrBr3−6 in AgBr
Authors: Deri R. J. , Spoonhower J. P.
Published: February 2003

The lifetime of photogenerated electrons in AgBr crystals doped with trivalent iridium ions was determined from photoconductivity measurements. A first-order electron decay process occurs at Ir3+ sites, with a room-temperature photoelectron lifetime of 13–150 ps for materials with 89–4 ppm of dopant. A cross section of 26±5 Å2 was deduced for photoelectron capture by IrBr3−6 centers.
Ultraviolet stimulated Raman scattering in multimode silica fibers pumped with excimer lasers
Authors: Pini Roberto , Mazzoni Marina , Salimbeni Renzo , Matera Manlio , Lin Chinlon
Published: February 2003

Efficient ultraviolet frequency conversion by stimulated Raman scattering in multimode silica glass fibers is reported. Two orders of stimulated Raman scattering have been obtained in the 313–358-nm spectral region pumping with the near ultraviolet emission lines of excimer lasers.
Transmission thermal-wave microscopy with pyroelectric detection
Authors: Baumann T. , Dacol F. , Melcher R. L.
Published: February 2003

A new form of thermal-wave microscopy is reported in which the thermal wave transmitted through a sample is detected by a pyroelectric sensor. A thermal image is formed by scanning a point heat source (an electron beam) over the surface of the sample. The image is sensitive only to thermal inhomogeneities in the sample and is independent of the elastic and optical properties of the sample and of the photothermal properties of the surrounding media.
Self-developing resist with submicrometer resolution and processing stability
Authors: Geis M. W. , Randall J. N. , Deutsch T. F. , DeGraff P. D. , Krohn K. E. , Stern L. A.
Published: February 2003

Nitrocellulose films have been shown to function as self-developing resist layers that are sensitive to both low-energy (<2 keV) Ar+ ions and to 193-nm UV radiation from pulsed excimer lasers. A resolution of <100 nm and aspect ratios >25:1 have been demonstrated using a stencil mask and an argon ion beam; the resolution obtained was mask limited. The sensitivity of the resist to 2-keV Ar+ ions is 36 μm/min at beam currents of 1 mA/cm2, allowing exposure times of 1 s for 0.5 μm of resist. The material is capable of functioning as a mask material for typical semiconductor dry etching processes.
Liquid phase epitaxial growth of InP/InGaAsP/InP double-heterostructure wafers free of misfit dislocations
Authors: Yamazaki Susumu , Nakajima Kazuo , Komiya Satoshi , Kishi Yutaka , Akita Kenzo
Published: February 2003

A liquid phase epitaxial growth method for obtaining InP/InGaAsP/InP double-heterostructure wafers free of misfit dislocations is presented. The feature of this method is that upper InP layers on InGaAsP are grown by two steps. The obtained structure becomes 2nd InP/1st InP/InGaAsP/InP. The misfit dislocation-free area was determined by photoluminescence and x-ray transmission topography. This area has been determined mainly at the stage when the growth of the first InP has been terminated and is scarcely dependent on the total thickness of the upper InP. Nearly misfit dislocation-free wafers with about 4-μm-thick InP could be obtained by making the first InP thinner than ∼1 μm.
New amorphous silicon majority-carrier device
Authors: Jang Jin , Lee Choochon
Published: February 2003

A new majority-carrier rectifying device is demonstrated which is made in hydrogenated amorphous silicon deposited by glow discharge decomposition. The devices were made in a structure composed of phosphorus doped, boron doped, intrinsic, and phosphorus-doped layers in series, prepared by using doping gas in the discharge. The rectification ratio at 1 V is over 106. Barrier heights depend on the thickness of boron-doped layer, and barriers as high as 1.09 eV are obtained with boron-doped layer of 120 Å. Conversion efficiencies of up to 5.7% under 20-mW/cm2 illumination have been observed.
Auger electron and x-ray photoelectron spectroscopy analysis of the hydrogenated amorphous silicon-tin oxide interface: Evidence of a plasma-induced reaction
Authors: Thomas J. H. , Catalano A.
Published: February 2003

Auger electron and x-ray photoelectron spectroscopies have been used to examine the chemistry of the hydrogenated amorphous silicon-tin oxide interface. Elemental tin is found in excess at the interface. Silicon dioxide resulting from a plasma-induced reduction of the tin dioxide surface is found throughout the thin silicon layer and peaks at the hydrogenated amorphous silicon-tin oxide interface.
Fabrication of periodic Ti:LiNbO3 waveguides by single and double diffusion
Authors: Yi-Yan Alfredo , Andonovic I. , Pun E. Y. B. , Bjortorp B.
Published: February 2003

Periodic index waveguides have been successfully fabricated by diffusing a 200-Å-thick titanium film containing a grating pattern into Y-cut LiNbO3 substrates. Bragg deflectors with efficiencies of up to 64% have been demonstrated in devices having a grating length of 750 μm and a diffusion time of 3 h. Similar devices have also been fabricated using a double-diffusion process to obtain high grating efficiencies in deeper waveguide layers. A deflection efficiency of 60% has been measured for a device having a total diffusion time of 11 h. While the diffusion of Ti gratings also leads to the formation of a surface corrugation on the waveguides, no increase in random scattering has been observed in the periodic region. The novel method of double diffusion could prove very useful in future integration of optical devices on a single LiNbO3 substrate.
Optically pumped cw semiconductor ring laser
Authors: Fuchs A. , Bebelaar D. , Salour M. M.
Published: February 2003

We report the first optically pumped semiconductor laser operating in a ring cavity configuration. Output powers of more than 40 mW have been achieved from a CdS platelet optically pumped by an Ar+ laser at 476 nm. Tunability of the laser output was demonstrated from 493–502 nm using an intracavity prism and temperature tuning.
Wide-band monolithic GaAs convolver and memory correlator
Authors: Melloch M. R. , Wagers R. S.
Published: February 2003

Experimental results for a monolithic GaAs convolver and memory correlator of time bandwidth 660 are reported. The device was fabricated on a semi-insulating GaAs substrate and ion implantation was used to define the 5.5-μs-long Schottky diode region. The interdigital transducers were chirped to provide a 120-MHz bandwidth at a center frequency of 300 MHz. With an untuned two-port insertion loss of 67.6 dB, an external convolution efficiency of –107 dBm and an external memory correlation efficiency of –120 dBm were obtained. Convolution and memory correlation with a 95-MHz chipping rate, 511 chip long, spread spectrum waveform are also demonstrated.
Effectiveness of polycrystalline silicon diffusion sources
Authors: Josquin W. J. M. J. , Boudewijn P. R. , Tamminga Y.
Published: February 2003

Boron and arsenic concentration profiles, diffused from polycrystalline silicon (polysilicon) into the underlying-single crystalline silicon (mono) substrate, were analyzed by Rutherford backscattering spectrometry and secondary ion mass spectrometry for various levels of oxygen concentration at the poly/mono interface. In contrast with previous reports it was found that chemically grown interfacial oxide layers of about 1.4-nm thickness provide more effective diffusion sources than oxygen-free interfaces. This surprising phenomenon is caused by the strong correlation between the crystalline structure of the polysilicon layer and the diffusion rates of dopant species in that layer. It is shown that the small amount of oxide at the poly/mono interface prevents the epitaxial realignment of the polysilicon, thereby maintaining high diffusion rates in the polysilicon, without offering a significant barrier to the diffusion of boron and arsenic across the interface.
Carrier dynamics at surface and interface in hydrogenated amorphous silicon observed by the transient grating method
Authors: Komuro Shuji , Aoyagi Yoshinobu , Segawa Yusaburo , Namba Susumu , Masuyama Akio , Okamoto Hiroaki , Hamakawa Yoshihiro
Published: February 2003

Carrier dynamics at a free surface and an interface in a glow discharge hydrogenated amorphous silicon (a:Si:H) film were observed by a transient grating method. The diffusion coefficients and lifetimes at the surface and in the bulk were determined separately by exciting carriers by selecting the wavelength of the excitation light. The diffusion coefficients and lifetimes in the bulk, at the surface and interfaces decreased in the following order: bulk, a:Si:H free surface, a-Si:H/substrate interface, a-Si C:H/a-Si:H interface.
Zone-melting germanium film crystallization with tungsten encapsulation
Authors: Ohmachi Yoshiro , Nishioka Takashi , Shinoda Yukinobu
Published: February 2003

Zone-melting crystallization of Ge film by using an rf zone-heating slider system is described. A buffer layer of tungsten between the germanium and the amorphous substrate was found to prevent molten germanium agglomeration. In addition to the buffer layer, the use of a tungsten capping layer was found to promote large area and flat surface growth. Crystallized material included a single crystal region ∼100 μm wide width and several millimeters long approximately along the zone-melt sliding direction. Also, single crystalline islands patterned into 80×140 μm rectangles were prepared. Auger electron analysis showed neither tungsten autodoping in crystallized germanium nor enhanced diffusion along grain and twin boundaries.
Hollow cathode reactive sputter etching—A new high-rate process
Authors: Horwitz Chris M.
Published: February 2003

A new rf sputter etching configuration is described which enables SiO2 rates as high as 12 nm s−1 (0.72 μm min−1) to be obtained at CF4 pressures as low as 0.1 Pa (0.75 mTorr) with 3.8–6.4 Wcm−2 and 1.5 kVp-p applied to the etched sample. Comparing these etch rates with standard reactive sputter etching at 1.5-kV peak-to-peak applied rf voltage, the present etch rates are a factor of 100 higher at 0.1 Pa (0.75 mTorr) and a factor of 10 higher at 10 Pa (75 mTorr). The new configuration consists of two closely spaced opposing electrodes, connected electrically together as an etching target. These electrodes correspond to the ‘‘hollow cathode’’ used in dc discharges, and an intense discharge forms in between them. Here the etching properties of this configuration are demonstrated using CF4 over a 0.1–10-Pa pressure range and with the applied rf voltage varied from 0.5 to 1.5 kV peak-to-peak.
Breakdown of the atmosphere by emission from a millimeter-wave free-electron maser
Authors: Gold S. H. , Black W. M. , Granatstein V. L. , Kinkead A. K.
Published: February 2003

Production of an atmospheric pressure air breakdown plasma using the emission from a short-pulse millimeter-wave free-electron maser is used to demonstrate frequency tunability over the range 50–100 GHz, via breakdown standing wave patterns, and very high peak power.
Conditions for metastable thermal and magnetic domain structures and for observable oscillations in dρ/d
T near an electrothermal instability
Authors: Ausloos M. , Sousa J. B. , Amado M. M. , Pinto R. P.
Published: February 2003

Experimental conditions for observing a new type of oscillations in the temperature derivative of the electrical resistivity near magnetic transition temperatures are discussed. An electrothermal instability arises due to a nonlinear electrical current-voltage drop characteristics as in a ballast resistor. Inhomogeneous temperature distributions are found for various experimental conditions.
Pyroelectric properties of the alanine and arsenic-doped triglycine sulfate single crystals
Authors: Bhalla A. S. , Fang C. S. , Xi Y. , Cross L. E.
Published: February 2003

Arsenic-doped triglycine sulfate single crystals show an enhancement in pyroelectric coefficients and the pyroelectric figures of merit p/K and p/√K by a factor of 2.2 over those of pure triglycine sulfate single crystals at the most desirable operating temperature of the pyroelectric sensors, ≂25 °C. The crystals are inexpensive to produce and show useful pyroelectric properties.
1.54-μm luminescence of erbium-implanted III-V semiconductors and silicon
Authors: Ennen H. , Schneider J. , Pomrenke G. , Axmann A.
Published: February 2003

Well-resolved sharply structured luminescence spectra at 1.54 μm were observed in erbium-implanted GaP, GaAs, InP, and Si. The optical transitions occur between the weakly crystal field split spin-orbit levels, 4I13/2→4I15/2, of Er3+(4f11). Typical spectral linewidths in GaAs are 2 cm−1(0.25 meV) at 6 K and 11 cm−1(1.36 meV) at room temperature.
Optical fiber loss increase in the infrared wavelength region induced by electric current
Authors: Murakami Yasuji , Uesugi Naoshi , Noguchi Kazuhiro , Mitsunaga Yutaka
Published: February 2003

A new phenomenon of silica-fiber loss increase, which is induced by an electric current applied in water, is reported. It is found from experimental results that the loss increase is caused by hydrogen gas, which is electrolytically produced and is diffused into the fiber interstitially.
B→X transition in 136Xe 19F
Authors: Tellinghuisen Patricia C. , Tellinghuisen Joel
Published: February 2003

The B→X emission spectrum is analyzed for the single isotopomer 136Xe 19F. Thirteen v′-v″ bands spanning v′=0–4 and v″=0–5 have been rotationally analyzed. The analysis yields greatly improved spectroscopic constants, permitting precise identification of most of the features in the XeF laser spectrum. No evidence is found for C→X emission in the normal sense. However, it is possible that several previously unassigned features, including one or more reported laser lines, constitute C→X emission enabled through intensity borrowing from B-X by B-C perturbative mixing.
Infrared transparent and electrically conductive thin film of In2O3
Authors: Chen Tze-chiang , Ma Tso-ping , Barker Richard C.
Published: February 2003

High quality infrared (1–12 μ) transparent and electrically conductive thin films based on thermal reactively evaporated In2O3 have been developed. Optical constants of these films have been obtained by the use of an iteration technique, which involves the formulas for multiple transmission and reflection. The details of the film deposition process and the theoretical foundation leading to its development are discussed in this letter. It has been found that the transparency and conductivity of these films are primarily due to their high electron mobility coupled with an appropriate electron concentration. A multilayer design of a bandpass induced transmission and antireflection coating has been developed and implemented on ZnS and ZnSe substrates for the wavelength range of 8–12 μ. Typical transmittance of 65%–80% with a film sheet resistance of 20–50 Ω/⧠ has been achieved. Such a design is applicable to forward-looking infrared systems where a window having both high electromagnetic (rf and microwave) shielding effectiveness and good infrared transparency are required. The properties of these films lend themselves to many other potential applications.
Rapid thermal annealing of arsenic and boron-implanted silicon
Authors: Narayan J. , Holland O. W. , Eby R. E. , Wortman J. J. , Ozguz V. , Rozgonyi G. A.
Published: February 2003

Annealing of ion implantation damage and concomitant electrical activation of dopants, depth profiles, and lattice location of dopants have been studied in arsenic and boron-implanted specimens after rapid thermal annealing. A ‘‘complete’’ annealing of displacement damage with full electrical activation of dopants and profile broadening less than 100 Å can be attained for shallow implants whereas some extended defects are retained for deep implants. Mechanisms of rapid thermal annealing and its implications in solid state device fabrication are discussed.
Hysteresis in the voltage dependence of cathodoluminescence
Authors: Ozawa Lyuji
Published: February 2003

It has been shown that the voltage dependence curve of cathodoluminescence from Zn2SiO4:Mn exhibits a hysteresis in the narrow voltage range just above the threshold voltage.

E;8378.60.Hk, 77.30.ed
Metal film removal and patterning using a XeCl laser
Authors: Andrew J. E. , Dyer P. E. , Greenough R. D. , Key P. H.
Published: February 2003

Single-shot removal of thin metal films on various substrates has been studied using a XeCl laser and thresholds compared with theoretical modeling of the interaction. Low thresholds and potential for micron resolution with large area projection patterning techniques are demonstrated.
Photothermal deflection microscopy of dielectric thin films
Authors: Mundy W. C. , Hughes R. S. , Carniglia C. K.
Published: February 2003

A system has been developed which employs the photothermal deflection effect to map the absorption characteristics of thin-film optical coatings used in high-energy laser applications. The high spatial resolution, low-level absorption data provided by this system may reveal flaws which could become damage sites when exposed to high-energy laser radiation. Qualitative data of mappings of areas of the coating in which defects were found which were not observed with Nomarski microscopy are presented. Measurements are in progress to ascertain correlations between the absorption sites and laser induced damage.
Photosensitive impregnated porous glass
Authors: Borrelli N. F. , Morse D. L.
Published: February 2003

Porous glass, impregnated with photosensitive organometallic compounds such as transition metal carbonyls, demonstrates induced optical changes when exposed to light. Both optical absorption and refractive index changes can be induced and are permanent after heating. Examples of high resolution optical patterns produced by this process are shown.
Multiline oscillation from a hybrid CO2 laser by cavity length tuning
Authors: Biswas D. J. , Bhadani P. K. , Nath A. K. , Chatterjee U. K.
Published: February 2003

A simple method of obtaining multiline oscillation on the P-branch transitions of the 10.6-μm band from a hybrid CO2 laser by precisely controlling the cavity length is described. To explain the mechanism of this scheme, theoretical results on multiline oscillation in a hybrid CO2 laser using the rate equation model are presented.
Strain measurements by channeling angular scans
Authors: Picraux S. T. , Dawson L. R. , Osbourn G. C. , Biefeld R. M. , Chu W. K.
Published: February 2003

We demonstrate the first direct measurement of strain in InxGa1−xAs/GaAs strained-layer superlattices by ion channeling angular scans. This technique permits quantitative measurement of the strain without requiring computer simulations of dechanneling. The measurements are generally applicable to the study of strain in heteroepitaxial layers.
High efficient GaAlAs light-emitting diodes of 660 nm with a double heterostructure on a GaAlAs substrate
Authors: Ishiguro Hisanori , Sawa Kazuhiro , Nagao Shigeru , Yamanaka Haruyoshi , Koike Susumu
Published: February 2003

A new type GaAlAs light-emitting diode of 660 nm with a double heterostructure fabricated on a GaAlAs substrate has been developed. It can provide high efficiency of 8.0% and high speed response with a cut-off frequency of 20 MHz. The GaAlAs substrate is transparent at the emission wavelength of 650–660 nm, bringing about a reduction of internal absorption to increase the efficiency. The DH structure produces a high speed of response by confining carriers in the thin active layer.
Effects of power and hydrogen in the discharge on the photovoltaic properties of sputtered amorphous silicon
Authors: Moustakas T. D. , Maruska H. P.
Published: February 2003

The photovoltaic properties of amorphous silicon films produced by reactive sputtering have been investigated as a function of power level and hydrogen concentration in the discharge. We find that raising the power in the discharge leads to films with better bulk properties but poorer surface properties. Increasing the hydrogen concentration in the discharge affects the photovoltaic properties of the films by increasing the optical gap of the film and simultaneously decreasing the density of states in the middle of the gap. Because of this dual role of hydrogen, films with optical gaps of 1.7–1.85 eV are capable of generating the same magnitude of short circuit current in sunlight. However, the large gap material is capable of providing a higher open circuit voltage and therefore results in solar cells with better overall performance.
X-ray generated ultrasound
Authors: Kim Kwang Yul , Sachse Wolfgang
Published: February 2003

This letter describes the first observations of x-ray generated ultrasonic signals in materials. The x rays used were the pulsed x-ray beams of continuous energy spectrum taken from a high-energy synchrotron source. The ultrasonic signals were detected with conventional piezoelectric transducers attached to stainless steel specimens.
Local oxidation induced dislocation generation near [100] Si3N4 film edges
Authors: Vanhellemont J. , Van Landuyt J. , Amelinckx S. , Claeys C. , Declerck G. , Van Overstraeten R.
Published: February 2003

The generation of dislocations at [100] nitride film edges on (001)Czochralski silicon wafers is studied by means of high voltage electron microscopy. After local oxidation 90° (edge) dislocations forming triangular half-loops with sides lying in [211̄] and [21̄1] directions in a (011) plane are found. It is observed that the shape of the surface stacking faults is also influenced by the mask orientation and that a denuded zone free from bulk defects is formed at the silicon surface. A novel model to explain the dislocation generation and movement under the influence of the stresses near the Si3N4 film edges is discussed.
Maskless chemical etching of submicrometer gratings in single-crystalline GaAs
Authors: Podlesnik D. V. , Gilgen H. H. , Osgood R. M. , Sanchez A.
Published: February 2003

Submicrometer optical gratings are produced in a GaAs surface by a laser-enhanced, wet-etching process which permits the fabrication of different grating profiles. The etch process was investigated by in situ optical measurements of the diffracted beams and electron microscopy.
Sealed-off CO2 lasers with La1−xSrxCoO3 oxide cathodes
Authors: Karube N. , Iehisa N. , Fukaya K. , Matsuo K.
Published: February 2003

Some of the perovskite oxides such as La0.7Sr0.3CoO3 sintered at 1150 °C can have the function, when used as cathode materials in sealed-off CO2 lasers, to improve both output power and operating life. While the output power of the order of 50 W/m has become obtainable in sealed-off tubes, the longest life observed was 4400 h. It has been shown that this improvement comes from the simultaneous presence of the following properties in some perovskites, of oxygen emissivity, catalytic activity, metallic conductivity, and low sputtering rate.
Orientation filtering by growth-velocity competition in zone-melting recrystallization of silicon on SiO2
Authors: Atwater H. A. , Thompson C. V. , Smith Henry I. , Geis M. W.
Published: February 2003

We describe a method of controlling the in-plane 〈100〉 directions of grains in (100)-textured silicon films produced by zone-melting recrystallization over amorphous SiO2. Grains having in-plane orientation within a narrow range are able to grow through an orientation filter consisting of a pattern of crystallization barriers, while grains having other orientations are occluded. The results of experiments using an orientation filter, and the parameters which optimize filter performance, are reported.
Improvement in high-field critical currents of i
n s
i
t
u processed Nb3Sn by titanium addition
Authors: Yoshida Y. , Togano K. , Tachikawa K.
Published: February 2003

The effects of the addition of a small amount of Ti to in situ processed Nb3Sn tape superconductors have been studied. It has been found that Ti addition significantly improves the critical current density Jc at high magnetic fields above 12 T. A Jc value of 3×104 A/cm2 at a magnetic field of 15 T parallel to the tape surface was obtained for the Cu-40 (Nb-1.6 wt. % Ti) tape reacted with Sn at 650 °C for 100 h. This enhancement in high-field performance can be associated with the incorporation of Ti into the A15 Nb3Sn.
Nonlinear photoacoustic measurement of laser pulse correlation functions
Authors: Schmid A. , Horn P. , Bräunlich P.
Published: February 2003

A simple method is described for the measurement of temporal characteristics of short picosecond-nanosecond laser pulses in the visible and near IR. It relies on the photoacoustic detection of two-photon absorption in thallous halides in an otherwise conventional correlation experiment.
Surface photoacoustic wave spectroscopy of thin films
Authors: Brueck S. R. J. , Deutsch T. F. , Oates D. E.
Published: February 2003

Time-resolved detection of the surface acoustic waves (SAW) generated upon relaxation of energy optically absorbed in surface films has been used to measure surface absorption spectra and laser-induced desorption cross sections. This new background-free spectroscopic technique is shown to be highly sensitive to the details of the film/substrate bonding. Minimum detectable molecular surface densities of 2×1011 cm−2 over an area of 10−3 cm2 have been demonstrated for rhodamine-590 dye on a crystal quartz substrate using a pulsed laser source and an edge-bonded SAW detector.
Thin-film thickness measurements with thermal waves
Authors: Rosencwaig Allan , Opsal Jon , Willenborg David L.
Published: February 2003

We have developed a method for measuring the thickness of thin films that is nondestructive, noncontact and that can make measurements with 2-μm spatial resolution (i.e., 2-μm spot size) on both optically opaque as well as optically transparent films. With this method, which is based on the use of high-frequency thermal waves, thicknesses of Al and SiO2 films on Si substrates have been measured in the 500–25 000-Å range.
Freedericksz transition of twisted nematic cells
Authors: Yang K. H.
Published: February 2003

A general formula for calculating the Freedericksz transition of twisted nematic liquid crystal cells has been derived by taking into consideration the following factors: unequal elastic constants and arbitrary dielectric anisotropy for the liquid crystal medium, and a general form of the anisotropic liquid crystal-to-substrate interfacial potential with negligible pretilt angle. The numerical computation of the threshold voltage as a function of the anchoring anisotropy has been demonstrated for two nematic mixtures. Increasing the degree of multiplexing of twisted nematic cells seems feasible using certain nematic mixtures with weak anchoring anisotropy.
Measurement of local stress in laser-recrystallized lateral epitaxial silicon films over silicon dioxide using Raman scattering
Authors: Zorabedian Paul , Adar Fran
Published: February 2003

Raman microprobe measurements of stress have been performed on a laser-recrystallized, seeded, lateral epitaxial silicon film on an oxidized silicon wafer. The direction-averaged, planar tensile stress increased from 2×109 dyn/cm2 in the seed region to 5×109 dyn/cm2 in the silicon-on-insulator region at distances greater than 20 μm from the seed/silicon-on-insulator boundary. Grain-boundary nucleation observed by optical Nomarski microscopy occurred approximately 11 μm from the seed edge in this film. Depth variations of the stress were observed by comparing measurements using 457-nm and 514.5-nm excitation wavelengths.
Density of gap states of silicon grain boundaries determined by optical absorption
Authors: Jackson Warren B. , Johnson N. M. , Biegelsen D. K.
Published: February 2003

The results of optical absorption measurements on fine-grain polycrystalline-silicon thin films indicate that the singly occupied dangling silicon bond lies 0.65±0.15 eV below the conduction-band minimum in the grain boundary. The grain boundary band gap is ∼1.0 eV and there is evidence for exponential tailing of the band edges. The optical absorption was determined by photothermal deflection spectroscopy. The dangling silicon bond density has been measured on polycrystalline-silicon thin films as a function of hydrogen passivation of the grain boundaries and on silicon-on-saphhire films. The optical absorption exhibits a defect shoulder which varies as the dangling bond density.
Test for nonthermal transient annealing in silicon
Authors: Baglin J. E. E. , Hodgson R. T. , Neri J. M. , Fastow R.
Published: February 2003

The proposition that nanosecond pulsed laser annealing of implanted silicon is accomplished by electron plasma interactions (below 1700 K) has been tested by comparing the threshold energy densities required for epitaxial regrowth, using intense pulsed beams of B+ and Ba+ ions. Thresholds for 250-ns pulsed B+ (210 keV) (90% electronic energy deposition in Si) and Ba+ (285 keV) (44% electronic, 56% collisional) are identical, indicating that the mode of initial energy coupling to the solid is not important. The results agree with quantitative predictions for a normal thermal melting process.
Effect of disorder on the martensitic phase transformation in Nb3Sn
Authors: Snead C. L. , Kumakura H. , Suenaga M.
Published: February 2003

Specimens of Nb3Sn tape have been irradiated at ∼380 K with reactor-spectrum neutrons to fluences of 1.3×1019 n/cm2 (E>1 MeV) and the internal friction and dynamic Young’s modulus measured from 6 to 300 K. The softening of the lattice with decreasing temperature is seen to decrease from 40% of the room-temperature value at 10 K for unirradiated Nb3Sn to 94% at a fluence of 1.3×1019 n/cm2. The internal friction δ due to tetragonal domain-wall motion of the transformed material decreased with increasing fluence, being completely suppressed after ∼4×1018 n/cm2. The transformation temperature Tm decreased from ∼49 K for the virgin specimen to 22 K for a fluence of 3.8×1018 n/cm2 with no evidence of any tetragonal transformation at all for higher fluences. The lattice-dynamical and electronic changes responsible for these effects are not known at this time, but are seen to be correlated with the neutron-induced disorder.
Long-lived GaAlAs laser diodes with multiple quantum well active layers grown by organometallic vapor phase epitaxy
Authors: Lindström C. , Paoli T. L. , Burnham R. D. , Scifres D. R. , Streifer W.
Published: February 2003

Proton-defined stripe geometry GaAlAs laser diodes with multiple quantum well active layers grown by organometallic vapor phase epitaxy have been operated continuously at 5 mW/facet for over 1800 h at 70 °C and over 1100 h at 100 °C. With a 0.7-eV activation energy, these times extrapolate respectively to 11.7 and 47.9 years of continuous operation at 20 °C. In the present mode of degradation, we estimate that the mean time to double the initial operating current is greater than 138 years at 20 °C.
Carrier leakage and temperature dependence of InGaAsP lasers
Authors: Chen T. R. , Chang B. , Chiu L. C. , Yu K. L. , Margalit S. , Yariv A.
Published: February 2003

A direct measurement of electron and hole leakage in InGaAsP/InP lasers has been carried out. The effect of electron leakage on the temperature sensitivity of InGaAsP/InP lasers has been revealed.
Operation of an inductively ballasted helical TE-CO2 laser
Authors: Biswas D. J. , Bhadani P. K , Rao P. R. K. , Chatterjee U. K. , Nath A. K. , Nundy U.
Published: February 2003

We report here the successful operation of a Beaulieu-type TE-CO2 laser using equalizing inductances. An improvement of 50% or more in the efficiency was observed over resistance-ballast system.
Surface acoustic wave mode conversion resonator
Authors: Martin S. J. , Gunshor R. L. , Melloch M. R. , Datta S. , Pierret R. F.
Published: February 2003

It is well known that a ZnO-on-Si structure supports two distinct surface waves, called the Rayleigh and the Sezawa modes, if the ZnO layer is sufficiently thick. Herein we report a unique surface wave resonator that operates by efficiently converting between the two modes at the resonant frequency. The mode conversion resonator promises enhanced out-of-band signal rejection since input and output coupling is effected through different modes.
Oxygen-induced recombination centers in as-grown Czochralski silicon crystals
Authors: Nauka K. , Gatos H. C. , Lagowski J.
Published: February 2003

Simultaneous quantitative microprofiles of the interstitial oxygen concentration and of the excess carrier lifetime were obtained, for the first time, in Czochralski-grown Si crystals employing double laser absorption scanning. It was found that oxygen concentration maxima and minima along the crystal growth direction coincide with lifetime minima and maxima, respectively. It was further found that the magnitude of oxygen-induced lifetime changes increases dramatically in going from the center to the periphery of the crystal. The present findings imply that ‘‘as-grown’’ oxygen precipitates are involved in lifetime limiting processes.
Epitaxial growth of Hg0.7Cd0.3Te by laser-assisted deposition
Authors: Cheung J. T.
Published: February 2003

Epitaxial n-type Hg0.7Cd0.3Te layers on (111)A CdTe substrates have been grown at 130 °C by laser-assisted deposition. Mobility and carrier concentration values at 77 K range from 4000 to 7000 cm2/Vs and 0.7 to 3×1016 cm−3, respectively. Films can be converted to  p type after annealing at 410 °C. Implanted n+/p photodiodes have been demonstrated.
Accumulation mode Ga0.47In0.53As insulated gate field-effect transistors
Authors: Wieder H. H. , Veteran J. L. , Clawson A. R. , Mullin D. P.
Published: February 2003

Preliminary results obtained on enhancement-type insulated gate field-effect transistors are described. These are based on the surface accumulation of heteroepitaxially grown Ga0.47In0.53As layers whose residual donor impurities are compensated by deep level Fe acceptors.
Superluminescent damping of relaxation resonance in the modulation response of GaAs lasers
Authors: Lau K. Y. , Ury I. , Bar-Chaim N. , Harder Ch. , Yariv A.
Published: February 2003

It is demonstrated experimentally that the intrinsic modulation response of injection lasers can be modified by reducing mirror reflectivities, which leads to suppression of relaxation oscillation resonance and a reduction of nonlinear distortions up to multi-GHz frequencies. A totally flat response with a 3-dB bandwidth of 5 GHz was obtained using antireflection coated buried heterostructure lasers fabricated on a semi-insulating substrate. Harmonic distortions were below 40 dB within the entire 3-dB bandwidth. These results are in accord with theoretical predictions based on an analysis which include the effects of superluminescence in the laser cavity.
Internal photoemission from quantum well heterojunction superlattices by phononless free-carrier absorption
Authors: Chiu L. C. , Smith J. S. , Margalit S. , Yariv A.
Published: February 2003

The possibility of phononless free-carrier absorption in quantum well heterojunction superlattices was investigated. Order of magnitude calculation showed that the absorption coefficient was significantly enhanced over the phonon-assisted process. Important aspects of the enhancement in the design of infrared photodetectors are discussed.
Squeezable electron tunneling junctions
Authors: Moreland John , Alexander S. , Cox M. , Sonnenfeld R. , Hansma P. K.
Published: February 2003

We report a versatile new technique for constructing electron tunneling junctions with mechanically adjusted artificial barriers. I-V curves are presented for tunneling between Ag electrodes with vacuum, gas, liquid, or solid in the barrier. An energy gap is apparent in the measured I-V curve when tunneling occurs between superconducting Pb electrodes.
Chemographic images of silicon surfaces
Authors: Blech I. A. , Meieran E. S.
Published: February 2003

Images are obtained when freshly etched or abraded silicon wafers are placed in contact with photographic plates. Based on the study of the images it was concluded that the images form due to a neutral chemical species, probably atomic hydrogen, that is emitted from the silicon surface during the initial stage of oxidation. These chemograhic images are a chemical parallel to normal autoradiographs. This letter describes experimental verification of the model and discusses possible uses of the technique.
High-efficiency GaP pure green light-emitting diodes of 555 nm fabricated by new liquid phase epitaxy method
Authors: Kawabata Toshiharu , Koike Susumu
Published: February 2003

A new liquid phase epitaxy (LPE) method, which can control impurity concentration by volatilization of impurities from the growth solution under reduced pressure, has been developed. Using this LPE method, high-efficiency GaP pure green light-emitting diodes, of which the peak wavelength is 555 nm, has been obtained. The average efficiency for a epoxy-encapsulated diode is 0.1% and the maximum efficiency is 0.14% at 16 A/cm2.
Spin dependent trapping in a polycrystalline silicon integrated circuit resistor
Authors: Schubert W. K. , Lenahan P. M.
Published: February 2003

Spin dependent trapping of majority carriers at trivalent silicon centers in the grain boundaries of a polycrystalline silicon integrated circuit resistor has been observed. The phenomenon has been studied both in a silicon bicrystal and in thin-film polycrystalline silicon with essentially identical results. This not only identifies the trapping center responsible for the large barriers observed at silicon grain boundaries, but also demonstrates that the technique has the sensitivity required to work with actual microelectronic devices.
Effect of beam energy and anneal history on trivalently bonded silicon defect centers induced by ion beam etching
Authors: Singh R. , Fonash S. J. , Caplan P. J. , Poindexter E. H.
Published: February 2003

Ion beam etching produces a modified layer at the surface of silicon which subsequently affects the electrical characteristics of devices fabricated on these surfaces. In this investigation it is shown that the modified layer resulting from low-energy ion beam processing contains a fundamental defect which has the signature of a trivalently bonded, silicon defect center. The evolution of the signature of this defect with ion beam energy and anneal history correlates with the evolution of the current-voltage characteristics of metal contacts made to the modified layer.
Lasing on the B→X band of cadmium monoiodide (CdI) and 114CdI in a UV-preionized, transverse discharge
Authors: Greene D. P. , Eden J. G.
Published: February 2003

Stimulated emission on the B→X band of CdI and isotopically enriched (98.6%) 114 CdI has been observed in a UV-preionized, transverse discharge device with a gain length of 50 cm. For natural CdI, the laser energy is distributed among several transitions between 656 and 658 nm. The isotopically enriched 114CdI spectrum, in contrast, is dominated by a single line at 657.1 nm, which contains >50% of the output energy. With a high-Q optical cavity, output energies >10 μJ have been measured in a 85-ns full width at half-maximum (FWHM) pulse.