bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoconductive response of compensating impurities in photothermal ionization spectroscopy of high-purity silicon and germanium
Authors: Darken L. S. , Hyder S. A.
Published: February 2003

In photothermal ionization spectroscopy both positive and negative photoconductivity responses have been reported from compensating centers neutralized by minority carriers generated by band-edge light. Here, the response of compensating impurities in both n-type and p-type high-purity (‖NA−ND‖ ≊1010–1012 cm−3) nuclear-detector-grade silicon and germanium is reported. Negative photoconductive responses from compensating impurities were observed only when the distance the photothermally generated majority carriers traveled before recapture by shallow levels was longer than the sample length (contact to contact). We propose that in high-purity semiconductors, such as used in this study, it is the contact configuration that is responsible for the apparent rapid recombination of minority carriers which causes negative minority-carrier photoconductivity. n+nn+ or p+pp+ structures allow multiple traversals through the sample by only majority carriers. The dependence of the band-edge light generated excess carrier density on applied electric field supports this mechanism.
Size effect of the longitudinal resistivity of multifilamentary superconducting wires
Authors: Cavalloni C. , Kwasnitza K. , Monnier R. , Horvath I.
Published: February 2003

Measurements on 22 different conductor samples, and numerical calculations based on Chambers’ kinetic formulation show conclusive evidence for the existence of a substantial size effect on the longitudinal resistivity of multifilamentary superconducting wires in the normal state. This may have important consequences for the design of such conductors.
Integrated optics wave front measurement sensor
Authors: Rediker R. H. , Lind T. A. , Leonberger F. J.
Published: February 2003

First results are presented demonstrating the feasibility of using an integrated optics array of Mach–Zehnder dielectric-waveguide interferometers to measure the phase and amplitude across an optical wave front. The interferometers are formed from single-mode waveguides produced by Ti diffusion into LiNbO3. The spacing between the arms of the interferometer is 20 μm. The phase difference φ between the optical waves incident on the two interferometers arms is measured and compared with theory. The excellent and reproducible agreement between experiment and theory over a number of interferometers suggests that the accuracy of the wave front measurement sensor should be attractively high, limited only by signal statistics and noise considerations. As example, a sensor design is given for which the rms deviation (1σ) in the value of φ is less than 4.5° (the rms deviation in the optical path difference is less than λ/80).
Laser oscillation at 3.53 μm from Fe2+ in n-InP:Fe
Authors: Klein P. B. , Furneaux J. E. , Henry R. L.
Published: February 2003

Using pulsed optical excitation (hν>Eg), we have observed laser oscillations at 3.53 μm from the internal d-shell transitions of Fe2+ in n-type InP:Fe. The semiconducting nature of the InP host plays an important role in the pumping of the Fe2+ excited state, which occurs via the capture of a conduction-band electron by Fe3+ created during the exciting pulse.
Nonlinear optical coupling between radiation and confined modes
Authors: Carter G. M. , Chen Y. J.
Published: February 2003

Equations are developed which describe the coupling between radiation and confined (guided wave or surface plasmon) modes in the presence of an intensity-dependent index of refraction. Solutions are presented for three numerical examples and comparisons are made with asymptotic solutions. We find that under certain conditions, the addition of the nonlinear index drastically alters the coupling and gives rise to the possibility of optical switching. Experimental parameters for optimizing such switching are discussed.
Ion-induced amorphous and crystalline phase formation in Al/Ni, Al/Pd, and Al/Pt thin films
Authors: Hung L. S. , Nastasi M. , Gyulai J. , Mayer J. W.
Published: February 2003

Amorphization by ion beam irradiation of multilayered samples of Al/Pt, Al/Pd, and Al/Ni has been investigated by selected area diffraction and Rutherford backscattering. With a dose of 2×1014 Xe ions/cm2, uniform mixing is achieved in the Al/Pt system and the amorphous phase is produced over a large composition range. In the Al/Pd and Al/Ni systems, amorphous phases or the equilibrium, crystalline phases are formed depending on the composition of the films. The same results were found when the samples were annealed to form crystalline phases before bombardment. For thin films of these fcc metals, only the simplest intermetallics, NiAl and PdAl, (primitive cubic structures with 2 atoms/cell) were formed in crystalline form by ion-beam irradiation.
Electro-optical light modulation in InGaAsP/InP double heterostructure diodes
Authors: Bach H. G. , Krauser J. , Nolting H. P. , Logan R. A. , Reinhart F. K.
Published: February 2003

The linear electro-optic coefficient r41 was determined in quaternary double heterostructure waveguides containing a p-n junction. Over the limited range of measurements, it is independent of wavelength and composition with a value r41=−1.4×10−10 cm/V. A strong quadratic electro-optic effect has been identified for the first time, which strongly depends on the band gap and photon energy as does the associated electroabsorption effect.
Crystallization of amorphous silicon films during low pressure chemical vapor deposition
Authors: Kinsbron E. , Sternheim M. , Knoell R.
Published: February 2003

The crystallization of low pressure chemical vapor deposition amorphous silicon films was studied by transmission electron microscope observations. The results demonstrate the interdependence of the silicon deposition rate, the incubation time for nucleation, and the crystalline growth rate. At temperatures below 600 °C the deposited films are amorphous, but partial crystallization can occur the deposition time is longer than the incubation time. Crystallization occurs through an epitaxial-like growth from nucleates near or at the substrate interface; the crystalline phase will reach the depositing interface for thick films if the growth rate exceeds the deposition rate. The crystallized fraction of the deposited layer can be controlled by regulating the deposition temperature and rate and by in situ addition of dopant impurities. At temperature higher than 600 °C the deposited films are polycrystalline and columnar in structure. The surface texture is much smoother for films whose surfaces are amorphous.
Photopumped low threshold Alx″Ga1−x″As -Alx′Ga1−x′As-AlxGa1−xAs (x″∼0.85, x′∼0.3, x=0) single quantum well lasers
Authors: Camras M. D. , Holonyak N. , Nixon M. A. , Burnham R. D. , Streifer W. , Scifres D. R. , Paoli T. L. , Lindström C.
Published: February 2003

Data are presented showing that it is possible to photopump and operate a quantum well heterostructure laser at equivalent current densities (Jeq) as low as 70 A/cm2. Continuous 300-K laser operation of a single 60-Å GaAs (x=0) quantum well in the center of a ∼0.12-μm-thick x′∼0.30 Alx′Ga1−x′As waveguide (and carrier reservoir), which is confined by x″∼0.85 Alx″Ga1−x″As layers, is demonstrated at Ieq∼0.4 mA (168 W/cm2, Jeq∼70 A/cm2). These quantum well heterostructures are grown by organometallic vapor phase epitaxy.
Growth of hydrogenated amorphous silicon due to controlled ion bombardment from a pure silane plasma
Authors: Drevillon B. , Perrin J. , Siefert J. M. , Huc J. , Lloret A. , de Rosny G. , Schmitt J. P. M.
Published: February 2003

The growth process, optical and structural properties of a-Si:H films deposited from a silane multipole dc discharge are analyzed by real time and spectroscopic ellipsometry, and ir absorption spectroscopy. Films deposited mainly from neutral polymerized species are systematically compared to films deposited from monomeric ionic species at various ion incident energy up to 100-eV. An increase of ion bombardment energy is shown to favor the formation of high density homogeneous and isotropic films.
Study of optically induced degradation of conductivity in hydrogenated amorphous silicon by transient grating method
Authors: Komuro Shuji , Aoyagi Yoshinobu , Segawa Yusaburo , Namba Susumu , Masuyama Akio , Okamoto Hiroaki , Hamakawa Yoshihiro
Published: February 2003

Optically induced degradation of the conductivity (the Staebler–Wronski effect) in glow discharge hydrogenated amorphous Si was examined by a transient grating method. It was clarified that the Staebler–Wronski effect was a bulk and not a surface effect, and the origin of the decrease of the photoconductivity was mainly attributed to the decrease of the lifetime instead of the mobility.
Characterization of disordered bonds in Si-implanted Ga0.47In0.53As with laser Raman spectroscopy
Authors: Kakimoto K. , Katoda T.
Published: February 2003

Difference in degree of disorder introduced by ion implantation into In–As and Ga–As bonds in Ga0.47In0.53As was studied with laser Raman spectroscopy. The disorder is introduced more easily into the In–As bond than into the Ga–As one. The disorder is removed simultaneously from both bonds with annealing at a temperature higher than 600 °C.
Measurement of cube-root broadening of charge packets in metal-oxide- semiconductor structures
Authors: Nelson D. F. , Abraham D. L. , Cooper J. A.
Published: February 2003

The spatial width of electron packets drifting in a nearly uniform electric field in a metal-oxide-semiconductor structure is determined from flux pulse measurements. The width is found to broaden as the cube root of time, thus verifying an earlier prediction. Furthermore, the broadening rate constant is found to agree with that predicted to within 7%.
Channeling contrast microscopy: Application to semiconductor structures
Authors: McCallum J. C. , McKenzie C. D. , Lucas M. A. , Rossiter K. G. , Short K. T. , Williams J. S.
Published: February 2003

The new technique is demonstrated for the imaging of semiconductor structures. The technique involves the use of a channeled 4He+ microbeam, scanned across the surface to provide a channeling-contrast image of subsurface lattice disorder and atom location. The present arrangement provides a lateral resolution of ∼5 μm and an in-depth resolution of ∼30 Å. The technique is applied to the imaging of small, laser annealed regions on ion implanted silicon wafers.
Characterization of Te precipitates in CdTe crystals
Authors: Shin S. H. , Bajaj J. , Moudy L. A. , Cheung D. T.
Published: February 2003

Te precipitates in CdTe have been characterized by Auger spectroscopy, x-ray diffraction, and Raman spectroscopy. The x-ray results show that the precipitated Te in Bridgman-grown CeTe crystals has the same structural phase as observed in elemental Te under high pressure. Auger and Raman microprobe spectroscopy were carried out to confirm Te precipitates in CdTe and identify the symmetry of the Te precipitates.
Titanium nitride Schottky-barrier contacts to GaAs
Authors: Waldrop J. R.
Published: February 2003

The electrical properties and interface chemistry of ideal titanium nitride Schottky-barrier contacts to GaAs are investigated by using x-ray photoemission spectroscopy (XPS), current-voltage (I-V), and capacitance-voltage (C-V) techniques. The TiN films were grown on clean n-type GaAs (100) surfaces by reactive evaporation of Ti in a NH3 atmosphere within the XPS system. The TiN-GaAs Schottky-barrier height is 0.83 eV. I-V and C-V measurements were made for a sequence of anneal temperatures up to 700 °C; the electrical properties are nearly ideal up to 600 °C. TiN is found to be a relatively inert nonmetallic alternative Schottky-barrier contact to GaAs that is suitable for high-temperature applications.
Interface traps generated by internal photoemission in Al-SiO2-Si structures
Authors: Zekeriya Viktor , Ma T. P.
Published: February 2003

Generation of interface traps by internal photoemission of electrons from both the Al interface and the Si interface of an Al-SiO2-Si structure has been studied. The generation rate differs significantly between steam oxide and dry oxide samples, and among the dry oxide samples, the post-metal-anneal (PMA) treatment results in an appreciable reduction of this rate. A characteristic peak in the interface trap distribution, similar to the one generated by ionizing radiation, has been observed for all samples. For a given injection condition, the magnitude of this peak depends on the oxidation and PMA treatments, and is in the order (steam oxide)>(dry oxide/no PMA)>(dry oxide/PMA). For a given sample, the peak increases with the applied electric field and the total injected charge for either polarity. When the injection is made from the Si interface, the generation rate also depends on the energy of the incident photons, while no such dependence is observed for injection from the Al interface. A qualitative model is proposed to interpret the observations.
Beam-propagation analysis of stripe-geometry semiconductor lasers: Threshold behavior
Authors: Agrawal G. P. , Joyce W. B. , Dixon R. W. , Lax M.
Published: February 2003

The axial and lateral variations of the optical mode and carrier-density profiles of a gain-guided double-heterostructure stripe-geometry semiconductor laser are analyzed theoretically using a beam-propagation method based on the fast Fourier transform technique. The numerical results near the laser threshold indicate that the characteristic length lc, over which the lateral mode adjusts itself to small axial variations in the laser structure, is typically in the range 50 μm≲lc≲100 μm.
Observation of HSiCl in a chemical vapor deposition reactor by laser-excited fluorescence
Authors: Ho Pauline , Breiland William G.
Published: February 2003

Using laser-excited fluorescence, free-radical HSiCl has been detected in the gas phase during the chemical vapor deposition of silicon from dichlorosilane. Profiles of the relative HSiCl density were measured at atmospheric and low total pressures. Previous studies of chlorosilane deposition have not considered HSiCl as a possible intermediate species. Therefore, its role in the deposition process must be investigated.
Temperature-dependent ferroelectric hysteresis study in polyvinylidene fluoride
Authors: Olsen R. B. , Hicks J. C. , Broadhurst M. G. , Davis G. T.
Published: February 2003

An experimental study of temperature-dependent ferroelectric hysteresis phenomena of polyvinylidene fluoride is presented. The temperature dependence of the remanent polarization and coercive field was measured from saturated ferroelectric hysteresis curves with a temperature range 60–130 °C. These data were then compared to a two-site and six-site ferroelectric switching model.
Electroreflectance investigation of (Ga1−xAlx)0.47In0.53As lattice matched to InP
Authors: Parayanthal P. , Ro C. S. , Pollak F. H. , Stanley C. R. , Wicks G. W. , Eastman L. F.
Published: February 2003

We present the first electroreflectance study of (Ga1−xAlx)0.47In0.53As lattice matched to InP (0≤x≤1) in the energy range 0.7–5.5 eV. The composition dependence of the E0 (fundamental band gap), E0+Δ0 (spin-orbit component), E1, E1+Δ1, E′0 , and E0+Δ′0 optical features, as well as the spin-orbit splitting parameters Δ0 and Δ1, have been determined. The variation of E0 with composition is in good agreement with recent photoluminescence measurements as well as with a band structure calculation. The bowing parameters of Δ0 and Δ1 will be discussed in terms of a generalized Van Vechten–Berolo–Woolley model.
n-type GaAs photoanodes in acetonitrile: Design of a 10.0% efficient photoelectrode
Authors: Gronet Chris M. , Lewis Nathan S.
Published: February 2003

n-type GaAs semiconductor/liquid junctions have been studied in acetonitrile (ACN) solvent with the ferrocene/ferricenium redox couple. Previously reported inefficiencies in this system are demonstrated to be due to bulk electron-hole recombination and not to recombination at the junction. Increases in minority-carrier collection length lead to increases in short circuit current of the n-GaAs/ferrocene/ferricenium cell in ACN, with photocurrent densities in excess of 21 mA/cm2 at 88 mW/cm2 of ELH-type tungsten-halogen irradiation. Properly prepared n-GaAs samples yield photoelectrode efficiencies of 10.0%±0.5% for conversion of natural sunlight (65 mW/cm2) to electricity, with open circuit voltages Voc of 0.70–0.72 V, short circuit currents of 16–17 mA/cm2, and fill factors of 0.52–0.56, when measured relative to the potential of a reversible reference electrode in the same solvent/redox couple/electrolyte solution.
Measurement of the conduction-band discontinuity of molecular beam epitaxial grown In0.52Al0.48As/In0.53Ga0.47As, N-n heterojunction by C-V profiling
Authors: People R. , Wecht K. W. , Alavi K. , Cho A. Y.
Published: February 2003

We report the first measurement of the conduction-band discontinuity ΔEc for molecular beam epitaxial grown N-n In0.52Al0.48As/In0.53Ga0.47As heterojunction using the C-V profiling technique outlined by Kroemer et al. We find ΔEc=(0.50±0.05) eV @297 K corresponding to (71±7)% ΔEg. An interface charge density σi of (4.0±0.8)×1011 cm−2 was also obtained. A knowledge of ΔEc is of importance for quantifying carrier confinement in double heterostructure lasers fabricated from these ternary compounds.
Magnetoconductance study of inversion layers on InAs metal-insulator-semiconductor field-effect transistors
Authors: Yamaguchi Eiichi , Minakata Makoto
Published: February 2003

Magnetoconductance properties have been studied on an n-type inversion layer in an InAs metal-insulator-semiconductor field-effect transistor. Two series of Shubnikov–de Haas oscillation have been first observed for conductivity in the n-channel of InAs, due to the two quantized subbands. It has been found that the multi-subband structure of electronic states gave rise to a remarkable effect on electron mobility in the inversion layer of InAs.
Observation of optically induced molecular reorientation in films of smectic C liquid crystals
Authors: Lippel P. H. , Young C. Y.
Published: February 2003

A linearly polarized laser beam incident on a freely suspended film of a smectic C liquid crystal has been observed to reorient the molecules. In films of 4, 4 bis (heptyloxy) azoxybenzene, large reorientations have been observed with an incident optical power of less than 50 mW. Photographs are presented showing the change in molecular orientation as the incident polarization is rotated. A simple theory explaining the effect is also included.
Cascade laser emission of optically pumped Na2 molecules
Authors: Wellegehausen B. , Luhs W. , Topouzkhanian A. , d’Incan J.
Published: February 2003

First continuous laser oscillation at wavelengths around 2.5 μm and 1.9 μm/0.9 μm on C 1πu →(3) 1Σ+g →B 1πu/A 1Σ+u cascade transitions of Na2 has been obtained. The C 1πu state is optically pumped with cw krypton and argon ion lasers at wavelengths in the range of 333–351 nm. Gain contributions due to coherent two-photon and three-photon processes are involved.
Generation and detection of ultrasonic Lamb waves in a thin deposited film by using interdigital transducers
Authors: Uozumi Kiyohiko , Ohsone Kaoru , White Richard M.
Published: February 2003

Interdigital transducers (IDT’s) have been used to generate and detect ultrasonic Lamb waves in a composite Cu(3 μm)-ZnO (0.45 μm) film that is much thinner than the acoustic wavelength in a bulk material. rf pulses of 29.0 and 1.31 MHz are applied to one of the pair of IDT’s with 140-μm period, giving rise to a nondispersive quasi-symmetric mode of phase velocity 4170 m/s and a dispersive quasi-antisymmetric mode having a phase velocity of 184 m/s and a group velocity of 362 m/s, respectively. Possible applications to electronic signal processing and material studies are described.
Measurements of plasma ion temperature and rotation velocity using the He II 4686-Å line produced by charge transfer
Authors: Groebner R. J. , Brooks N. H. , Burrell K. H. , Rottler L.
Published: February 2003

Spatially and temporally resolved values of the ion temperature and toroidal rotation velocity near the plasma axis have been obtained in neutral beam-heated plasmas in the Doublet III tokamak from measurements of the Doppler broadening and Doppler shift of the He II 4686-Å line, excited by charge transfer reactions between fast hydrogen atoms in the beam and thermal helium ions in the plasma. The measurement technique, which uses visible optics and a multichannel detector, promises to be a straightforward method to obtain ion temperature profiles in beam-heated tokamaks.
Ion channeling studies of InGaAs/GaAs strained-layer superlattices
Authors: Picraux S. T. , Dawson L. R. , Osbourn G. C. , Chu W. K.
Published: February 2003

The first ion channeling studies of the InxGa1−xAs/GaAs strained-layer superlattice (SLS) system are reported. The strong orientation dependence of the dechanneling for both axial and planar directions relative to the [100] growth axis indicates that the ≊1% lattice mismatch is accommodated by lattice strain. Tetragonal distortions along the growth direction give rise to alternating tilts for inclined crystal directions which result in significant [110] and (1̄10) dechanneling. Measurements for 40-layer structures with different In concentrations demonstrate that the channeling technique is a depth-sensitive probe of the degree of strain in SLS systems.
Optimum emitter grading for heterojunction bipolar transistors
Authors: Hayes J. R. , Capasso F. , Malik R. J. , Gossard A. C. , Wiegmann W.
Published: February 2003

A simple procedure has been used to determine the optimum emitter grading for a heterojunction bipolar transistor (ABT). Use of this procedure allows maximum hole confinement in addition to minimum base/emitter turn-on voltage, leading to a negligible collector/emitter offset voltage, both of which are necessary for high performance devices. By using a parabolic grading function at the emitter/base junction a Np+n Ga0.7Al0.3As/GaAs HBT has been fabricated, using molecular beam epitaxy, with a negligible collector/emitter offset voltage. A similar result can be obtained with a N-i emitter where the undoped i region is linearly graded.
Cold hydrostatic extrusion of powder metallurgy processed superconducting materials
Authors: Pourrahimi S. , Thieme C. L. H. , Foner S. , Murphy R. J.
Published: February 2003

Hydrostatically extruded multifilamentary composites of Cu-Nb, Cu-Nb with a central tin core and Nb-Al were directly drawn to fine wires without intermediate annealing. Uniform deformation was observed throughout the process. Cu-Nb composite wires were Sn plated for external diffusion. Overall critical current densities of better than 104 A/cm2 at 16 T were achieved for Nb3Sn-Cu composite wires with nominal areal reductions of 2000.
Room-temperature pulsed operation of AlGaInP/GaInP/AlGaInP double heterostructure visible light laser diodes grown by metalorganic chemical vapor deposition
Authors: Hino Isao , Gomyo Akiko , Kobayashi Kenichi , Suzuki Tohru , Nishida Katsuhiko
Published: February 2003

Room-temperature pulsed laser operation of (Al0.3Ga0.7)0.5In0.5P/ Ga0.5In0.5P/ (Al0.3Ga0.7)0.5In0.5P double heterostructure laser diodes grown by metalorganic chemical vapor deposition has been achieved for the first time. The lowest threshold current density was 26 kA/cm2 for a diode with a 22-μm-wide and 160-μm-long stripe. The lasing wavelength was 0.683 μm.
Equal-pulse correlation technique for measuring femtosecond excited state relaxation times
Authors: Taylor A. J. , Erskine D. J. , Tang C. L.
Published: February 2003

A new technique for measuring extremely fast excited state relaxation times, on the order of or less than the laser pulse width, in the presence of a longer relaxation time is described. The difficulties involved in using the conventional pump-and-probe technique and the corresponding advantages of the new technique are illustrated with numerical examples for specific three-level systems. Qualitative experimental results on semiconductors and organic dye molecules substantiating the results are shown.
Laser recrystallization of silicon stripes in SiO2 grooves with a polycrystalline silicon sublayer
Authors: Egami Koji , Kimura Masakazu , Hamaguchi Tsuneo
Published: February 2003

A new substrate structure has been proposed for obtaining laser-recrystallized silicon on quartz glass. Single crystal Si stripes as large at 12×500 μm, dielectrically isolated with a width as small at 1.5 μm, have been obtained by use of the new structure, in which polysilicon stripes are placed in SiO2 grooves and a polycrystalline silicon sublayer is inserted between the SiO2 layer and quartz glass to improve the thermal profile in recrystallization. The proposed structure is useful for realizing both enlargement and positional control of Si grains.
Lateral solid phase epitaxy of amorphous Si films on Si substrates with SiO2 patterns
Authors: Ishiwara Hiroshi , Yamamoto Hiroshi , Furukawa Seijiro , Tamura Masao , Tokuyama Takashi
Published: February 2003

Lateral solid phase epitaxy of amorphous Si films vacuum evaporated on Si substrates with SiO2 patterns has been investigated, in which the films first grow vertically in the region directly contacted to the Si substrates and then grow laterally onto SiO2 patterns. It was found from transmission electron microscopy and Nomarski optical microscopy that the lateral growth occurred in dense amorphous Si films formed by evaporation on heated substrates and subsequent amorphization by Si+ ion implantation, but it hardly occurred in porous films deposited at room temperature. The maximum length of the epitaxial film on SiO2 was about 6 μm after 10-h annealing at 600 °C.
Electrical properties of undoped and Si-doped Al0.48In0.52As grown by liquid phase epitaxy
Authors: Tanahashi Toshiyuki , Nakajima Kazuo , Yamaguchi Akio , Umebu Itsuo
Published: February 2003

Electrical properties of undoped Al0.48In0.52As layers grown by liquid phase epitaxy (LPE) were studied for the first time. The carrier concentration n(cm−3) and the mobility μ(cm2/Vs) were μ=4600 cm2/Vs at n=4.7×1015 cm−3 and μ=4500 cm2/Vs at n=5.9×1015 cm−3 at room temperature. The doping data of Si in LPE-grown Al0.48In0.52As and the resulting mobility and carrier concentration were also studied. The distribution coefficient of Si was determined to be 0.019. The mobility of Al0.48In0.52As is comparable to that of InP when compared at the same carrier concentration.
Water acoustic microscopy at suboptical wavelengths
Authors: Hadimioglu B. , Quate C. F.
Published: February 2003

An acoustic microscope using water as the coupling medium has been operated at frequencies up to 4.4 GHz. The signal-to-noise ratio is sufficient for imaging and the acoustic images demonstrate that the resolution is better than 2000 Å when the instrument is operated in the nonlinear regime.
Suppression of low angle grain boundaries in seeded thick Si films recrystallized between SiO2 layers
Authors: Pfeiffer Loren , Celler G. K. , Kovacs T. , Robinson McD.
Published: February 2003

We observe a marked suppression in the formation of low angle grain boundaries (sub-boundaries) during the graphite strip heater recrystallization of thick Si films over buried islands of SiO2. For 27-μm-thick Si films, areas exceeding 1×1 mm2 have been recrystallized on SiO2 which are completely free of grain boundaries and sub-boundaries, but which contain dislocations in other configurations. Moreover, we find the density of these remaining dislocations to be much reduced near the upper and lower SiO2 interfaces.
Dependence of laser-induced damage of surface layers of GaP on pulse width and wavelength
Authors: Okigawa Mitsuru , Nakayama Takeyoshi , Morita Kenji , Itoh Noriaki
Published: February 2003

Disorder induced by irradiation with a laser pulse on surface layers of GaP has been studied by means of the Rutherford backscattering channeling technique. It is found that a 0.6-μs laser pulse near the direct band gap and a 15-ns laser pulse near the indirect band gap induce damages more pronounced than a 15-ns laser pulse near the direct band gap of the same fluence. Moreover, decomposition of the surface layers into Ga-rich and P layers is found to be induced by irradiation with a 0.6-μs laser pulse. It is suggested that such a decomposition occurs when heating is not substantial.
Energy gap versus alloy composition and temperature in Hg1−xCdxTe
Authors: Chu Junhao , Xu Shichou , Tang Dingyuan
Published: February 2003

An empirical expression for the energy band gap Eg of Hg1−xCdxTe versus the temperature and alloy composition, deduced from optical absorption data for thin samples with different composition x, is reported as Eg =−0.295+1.87x−0.28x2+(6−14x+3x2) (10−4)T+0.35x4, which is applicable to the ranges of 0≤x≤0.37 (plus x=1) and 4.2≤T≤300 K. The values Eg of this expression are uniformly higher than the expressions of Hansen, Schmit, and Casselman. By comparing both expressions with the known magneto-optical experimental data at 4.2 and 24 K, we find that for this expression the standard error of estimate is 0.008 eV which is better than the expression of Hansen et al.
High-power phase-locked arrays of index-guided diode lasers
Authors: Botez D. , Connolly J. C.
Published: February 2003

A nine-unit phase-locked array of index-guided channel-substrate-planar large-optical-cavity AlGaAs diode lasers is fabricated by one-step liquid phase epitaxial growth over a 5-μm period sawtooth grating etched into a GaAs substrate. Two-lobed, 180° phase shift operation is achieved to 75-mW cw power and to 400-mW peak pulsed power. Strong coherent optical coupling between the array units provides single-longitudinal-mode array operation to 80-mW cw output power. The cw and pulsed threshold currents are in the 250–400-mA range. Single-lobe, 0° phase shift operation, with the single beam peaked at 0°, is achieved to 200-mW peak power.
Investigation of the silicon beading phenomena during zone-melting recrystallization
Authors: Weinberg Z. A. , Deline V. R. , Sedgwick T. O. , Cohen S. A. , Aliotta C. F. , Clark G. J. , Lanford W. A.
Published: February 2003

During recrystallization of encapsulated silicon films on SiO2, by the graphite strip heater technique, the silicon sometimes breaks apart and agglomerates into small beads or stripes. By secondary ion mass spectroscopy analysis, it was found that a high concentration of nitrogen at the interface between the silicon and the top SiO2 capping layer is needed to prevent this from occurring. Incorporation of hydrogen into the crystallization ambient was found to cause the beading to occur. The initial stages of the bead formation were investigated by scanning electron cross-section microscopy.
Optical absorption tail in InP:Mn from surface photovoltage measurements
Authors: Chiang C. L. , Wagner S. , Ballman A. A.
Published: February 2003

The steady-state surface photovoltage technique was used to determine the optical absorption tail of InP:Mn, by extrapolation from the above-band-gap absorption spectrum. Reabsorbed recombination radiation is shown to have no effect on this procedure although it does raise the effective minority-carrier diffusion length. The tail absorption coefficient of InP:Mn increases with hole density in the range of 4.1×1014 cm to 5.3×1016 cm−3. In the 1016 cm−3 range, the absorption coefficient appears to rise also with the density of dislocations.
Platinum diffusion into silicon from PtSi
Authors: Prabhakar A. , McGill T. C. , Nicolet M-A.
Published: February 2003

We have observed platinum diffusion into the silicon underlying a PtSi film. Silicon substrates covered with platinum films were annealed at temperatures from 300 to 800 °C to form the silicide. Backscattering spectrometry spectra show no degradation of the silicide in the samples treated below 700 °C. Deep level transient spectroscopy (DLTS) was used to measure diffused platinum electron traps. Electron trap concentrations in samples treated below 700 °C are below the DLTS detection limit of 5×1011/cm3. Trap concentration profiles for the samples annealed at higher temperatures were obtained. These profiles cannot in general be explained by simple diffusion from an infinite source of platinum at the surface.
High speed logic operations of all refractory Josephson integrated circuits
Authors: Kosaka Shin , Shoji Akira , Aoyagi Masahiro , Shinoki Fujitoshi , Nakagawa Hiroshi , Takada Susumu , Hayakawa Hisao
Published: February 2003

A chain circuit of four-junction logic gates consisting of all refractory junctions with niobium nitride (NbN)-niobium (Nb) double-layered electrodes has been fabricated with a 2.5-μm minimum feature. A reactive ion etching technique has been used for patterning every layer such as junction electrodes, molybdenum resistors, and insulation layers. The minimum logic delay of 18 ps/gate has been obtained in the experimental circuit.
Threshold-wavelength and threshold-temperature dependences of GaInAsP/InP lasers with frequency selective feedback operating in the 1.3- and 1.5-μm regions
Authors: Tsang W. T. , Olsson N. A. , Logan R. A.
Published: February 2003

We have shown for the first time that a detailed and systematic study of the threshold-wavelength and the threshold-temperature dependences at different lasing wavelengths of laser diodes with built-in frequency selective feedback (FSF) mechanisms such as distributed feedback lasers, distributed Bragg reflector lasers, and lateral-evanescent field distributed feedback lasers, can be conveniently performed by utilizing external cavity semiconductor lasers with frequency selective feedback. The results obtained show that the position of the FSF lasing mode within the spectral gain profile of the laser significantly affected the threshold current and threshold-temperature dependence.
A novel technique for enhancing photoacoustic signals from solids
Authors: Ganguly P. , Somasundaram T.
Published: February 2003

Enhancement of the photoacoustic signal from condensed materials by several folds is achieved by the introduction of a liquid with high vapor pressure in the photoacoustic cell. The enhancement is especially marked for low absorption coefficients and high chopping frequencies. Typically the enhancement is two to nine times in the presence of diethyl ether at 293 K. A linear relationship is observed between the enhancement and the vapor pressure of the liquid.
Position of the degradation and the improved structure for the buried crescent InGaAsP/InP (1.3 μm) lasers
Authors: Hirano R. , Oomura E. , Higuchi H. , Sakakibara Y. , Namizaki H. , Susaki W. , Fujikawa K.
Published: February 2003

We have found a degradation of the buried crescent (BC) InGaAsP/InP lasers that occurs when the p-n junction plane coincides with the surface exposed in the high-temperature H2 ambient before the melt contact during the liquid phase epitaxial growth. To eliminate the degradation, we have fabricated a new structure of the BC laser and have obtained stable cw operation at 80 °C.
High voltage optoelectronic switching in diamond
Authors: Bharadwaj P. K. , Code R. F. , van Driel H. M. , Walentynowicz E.
Published: February 2003

Subnanosecond photoconductive switching has been observed in ultraviolet illuminated type IIa diamonds. Switching efficiencies up to 50% were attainable in coaxially mounted samples for direct current bias voltage as high as 8 kV at room temperature.
High magnetic field studies of the two-dimensional electron gas in GaInAs-InP superlattices
Authors: Portal J. C. , Nicholas R. J. , Brummell M. A. , Razeghi M. , Poisson M. A.
Published: February 2003

We report the observation of Shubnikov–de Haas oscillations in superlattices of GaInAs and InP, showing evidence of two-dimensional behavior. The electron g-factor is deduced from both the criteria for resolution of a spin splitting by comparison with the broadening parameter Γ, and from the tilted field method, and is shown to increase with increasing resolution of the Landau levels in a manner consistent with the theory of Ando and Uemura. In the ultraquantum limit, structure at ν=1/2 and ν=1/3 is observed.
Modulation-doped Ga0.47In0.53As/Al0.48In0.52As planar photoconductive detectors for 1.0–1.55-μm applications
Authors: Chen C. Y. , Pang Y. M. , Garbinski P. A. , Cho A. Y. , Alavi K.
Published: February 2003

We demonstrate a Ga0.47In0.53As/Al0.48In0.52As modulation-doped photoconductive detector. The detector has a built-in electric field to separate photogenerated electron-hole pairs. This allows the electron lifetime to be precisely determined by electrode spacings. When tested by a 200-ps, λ=1.3  μm laser pulse, the detector shows an internal gain of 18, a peak external quantum efficiency of 300%, a rise time of 80 ps, a full width at half-maximum of 250 ps, and an internal gain-bandwidth product of 72 GHz. Typical devices have 4-μm spacings between electrodes and 94-μm widths. The detector has a spectral response between 0.6 and 1.65  μm with a dip at 0.86  μm. We also measured the noise power of the detector at room temperature. With its capability to be integrated with a modulation-doped field-effect transistor, this detector can be useful in a monolithic integrated photoreceiver.
Highly sensitive photodetection using a microwave-coupled BaPb0.7Bi0.3O3 Josephson junction array
Authors: Ito Minoru , Enomoto Youichi , Murakami Toshiaki
Published: February 2003

The BaPb0.7Bi0.3O3 sputtered film possesses tunnel Josephson junctions at boundary layers [boundary Josephson junction (BJJ)] normal to the film plane in a homogeneous junction array. The film has high efficiency for optical irradiation of the junctions because of the high optical transparency. The letter presents the optical effect on the current-voltage characteristics for this Josephson junction array locked to a microwave field. The microwave-induced hysteresis loop caused by voltage locking among junctions in a microwave field is highly sensitive to optical illumination with as low an incident power as a few nanowatts. This probably can be exploited in a future, highly sensitive photodetector.
Multigigahertz-bandwidth linear-frequency-modulated filters using a superconductive stripline
Authors: Lynch J. T. , Withers R. S. , Anderson A. C. , Wright P. V. , Reible S. A.
Published: February 2003

Superconducting niobium patterned to form strip transmission lines on sapphire and silicon dielectric substrates has been used to make passive delay lines, capacitively coupled resonators, and linear-FM chirp filters. Chirp filters with a 37.5-ns dispersion and 2.3-GHz bandwidth were implemented by nonuniformly tapping nondispersive delay lines using proximity directional couplers. Pulse compression tests using two complementary filters agree well with theory. The results demonstrate a technology which promises to provide analog signal processing with about an order of magnitude bandwidth increase over surface-acoustic-wave and acousto-optic devices.
Propagation of magnetic bubbles on ion implanted patterns in a (100)Bi-yttrium iron garnet film
Authors: Wolfe R. , Luther L. C. , LeCraw R. C. , Lieberman R. A.
Published: February 2003

Magnetic bubbles have been propagated on ion implanted patterns in a (100) garnet film for the first time. Charged walls form in the implanted layer at the edges of unimplanted features due to stress relief at the pattern edges. In response to a rotating in-plane field, they circulate completely around unimplanted circles and 8-μm contiguous disk patterns, carrying underlying bubbles along. This is because in the Bi-yttrium iron garnet composition used, the magnetostriction coefficients λ100 and λ111 are both negative.
Laser driven compression experiments using low x-ray opacity polymer shells
Authors: Kilkenny J. D. , MacGowan B. J. , Rumsby P. T.
Published: February 2003

The use of polymer shells, filled with dichlorodifluoromethane in laser compression experiments is described. The absence of shell emission leads to chlorine spectra with little contaminating shell continuum emission. The low x-ray opacity of polymer indicates that chlorine heliumlike emission could be detected even with compressed shell areal density of 0.1 gm cm−2.
Suppression of feedback-induced noise in short-cavity V-channeled substrate inner stripe lasers with self-oscillation
Authors: Matsui S. , Takiguchi H. , Hayashi H. , Yamamoto S. , Yano S. , Hijikata T.
Published: February 2003

Self-oscillations of V-channeled substrate inner stripe (VSIS) lasers with index guiding and the influence of external feedback on low-frequency noise generation are presented. The self-oscillation is induced by means of shortening a cavity length of VSIS laser to 110 μm. VSIS lasers with self-oscillation have the fundamental linewidth of 0.56 Å below 3 mW and are not sensitive to both phase and amplitude of the externally reflected light. Signal to noise ratio of short-cavity VSIS laser at 1 MHz with a 10-KHz bandwidth was 97 dB at 0.05% optical feedback.
Long-range surface plasmons in electrode structures
Authors: Stegeman G. I. , Burke J. J.
Published: February 2003

We show that surface plasmon polaritons guided by thin metal electrodes can achieve millimeter plus propagation distances in the near infrared.
Growth of metastable Cu1−xCrx solid solutions by ion mixing during bias-sputter deposition
Authors: Shin S. M. , Ray M. A. , Rigsbee J. M. , Greene J. E.
Published: February 2003

The Cu-Cr system exhibits a miscibility gap in the liquid and has essentially no solid solubility. However, using low energy, <160 eV, Ar+ ion bombardment of the growing film to promote ballistic collisional mixing, metastable single phase face-centered-cubic Cu-rich and body-centered-cubic Cr-rich solid solutions have been grown on amorphous glass substrates at 75 °C. The films were typically 1 μm thick with average grain sizes of 90 and 110 nm, respectively, and a (111) preferred orientation. Annealing studies combined with x-ray and electron diffraction analyses showed that the films have good thermal stability against phase separation at temperatures up to 400 °C. The metastable to equilibrium phase transformation occurred with the precipitation of an essentially pure second phase, rather than through a continuous series of metastable states, due to structural constraints.
High-speed GaAlAs/GaAs p-i-n photodiode on a semi-insulating GaAs substrate
Authors: Bar-Chaim N. , Lau K. Y. , Ury I. , Yariv A.
Published: February 2003

A high-speed, high-responsivity GaAlAs/GaAs p-i-n photodiode has been fabricated on a GaAs semi-insulating substrate. The 75-μm-diam photodiode has a 3-dB bandwidth of 2.5 GHz and responsivity of 0.45 A/W at 8400 Å (external quantum efficiency of 65%). The diode is suitable for monolithic integration with other optoelectronic devices.
Epitaxial film transfer technique for producing single crystal Si film on an insulating substrate
Authors: Kimura M. , Egami K. , Kanamori M. , Hamaguchi T.
Published: February 2003

Epitaxial film transfer, a new technique for producing a single crystal Si film with both large size and high quality on an insulating substrate, is demonstrated. The technique in which an epitaxial Si film is transferred to a secondary substrate by using three fundamental processes of epitaxial growth, bonding of two wafers, and substrate elimination, can produce a 2-in. single crystal Si film as thin as 1.5 μm on a insulating substrate. Thickness variation can be controlled to ±0.06 μm across a 2-in. wafer. An epitaxial Si film is transferred without significant degradation in quality although a fine film waving exists.
Anodic bonding of gallium arsenide to glass
Authors: Hök Bertil , Dubon Chantal , Ovrén Christer
Published: February 2003

We describe a modified anodic bonding technique for hermetic sealing between GaAs and glass, the modification being called for by the formation of a nonadherent oxide layer during the bonding process. We show that this can be avoided by prebaking the glass and performing the bonding operation in a reducing atmosphere. With this technique, strong, hermetic seals can be produced. Parameter dependence has been studied theoretically by solving the continuity equation for a one-dimensional model of the experimental situation. Experimentally, the bonds were evaluated with a number of methods, giving support for a model consisting of a high-field, sodium-depleted zone in the interface region during bond formation. The described technique is of particular interest for optoelectronic devices requiring transparent and hermetic seals.
Two-dimensional electron gas in a selectively doped InP/In0.53 Ga0.47As heterostructure grown by chloride transport vapor phase epitaxy
Authors: Takikawa M. , Komeno J. , Ozeki M.
Published: February 2003

A selectively doped InP/In0.53Ga0.47As heterostructure has been prepared by chloride transport vapor phase epitaxy. Hall and Subnikov-de Haas measurements revealed the existence of a high mobility, two-dimensional electron gas at the interface of this heterostructure. Enhanced electron mobilities were as high as 106 000, 71 200, and 9 400 cm2/Vs at 4.2, 77, and 300 K, respectively. These indicate the excellent interface properties of the selectively doped InP/In0.53Ga0.47As heterostructure grown by chloride transport vapor phase epitaxy.
Discovery of dc switching of a bistable boundary layer liquid crystal display
Authors: Meyer Robert B. , Thurston R. N.
Published: February 2003

A liquid crystal display based on bistable boundary layer configurations has been shown previously [Cheng et al., Appl. Phys. Lett. 40, 1007 (1982)] to have memory, adequate contrast, low-voltage operation, and a bistability that is relatively insensitive to changes in material properties, cell parameters, and temperature. We report here the discovery that a short, low voltage dc pulse switches the display into one or the other of its bistable states, depending on the polarity of the pulse. Experiments suggest that a storage display of this type having n lines of pels can be rewritten in (50+20n) milliseconds using voltages of less than 2 V. Consequently, a large area, low power, nonrefreshed display is possible.
Thermal wave remote and nondestructive inspection of polymers
Authors: Busse G. , Eyerer P.
Published: February 2003

Optically generated thermal waves propagating in various kinds of polymers (adhesives, coatings, fiber reinforced polybutyleneterephthalate, oriented polyethylene) are analyzed by photothermal detection. Some results from this remote technique are difficult to obtain by conventional methods.
Rectification and harmonic generation with metal-insulator-metal diodes in the mid-infrared
Authors: Klingenberg H. H. , Weiss C. O.
Published: February 2003

Different current-voltage characteristics were found for diodes with Ni and Nb substrates. The diode bias dependence of the rectified signals at 30, 88, and 118 THz (CO2, He-Ne, color-center laser) is found to correspond to the dc characteristics in both cases. Harmonic mixing between CO2 and He-Ne laser, CO2 and color-center laser respectively, was obtained for one of these characteristics only.
Pulsed ion beam technique for measuring diffusion coefficient of a slow diffusant in polymers
Authors: Venkatesan T. , Edelson D. , Brown W. L.
Published: February 2003

The determination of diffusion coefficients (D) of small molecules in a polymer for D below 10−10 cm2 s−1 is a difficult measurement using conventional self-supporting polymer membrane techniques. We propose a new method for obtaining similar information by irradiating a polymer with a pulsed ion beam and studying the evolving gaseous products. Product molecules that are not limited by the rate of their production in the film tend to exhibit diffusion limited dynamical characteristics in their transient evolution from the surface. By numerically modeling the diffusion problem we can extract diffusion coefficients from the data. Since thin films (<1 μm) can be used in these experiments, diffusion coefficients less than 10−10 cm2 s−1, typical of many molecules in polymers, can be measured with ease.