bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of atmosphere during arsenic diffusion in silicon from doped oxide
Authors: Sakurai T. , Nishi H. , Furuya T. , Hashimoto H. , Shibayama H.
Published: January 2004

The effects of N2 and O2 atmospheres on arsenic diffusion in silicon from a doped oxide are studied by the backscattering method. The results indicate that the amounts of arsenic atoms diffused in silicon in a N2 atmosphere are smaller than those in an O2 atmosphere. This is caused by the differences in the properties of the silicon-doped oxide interface during diffusion; the elemental arsenic is accumulated at the oxide side of the interface during diffusion in N2, whereas arsenic remains in the state of an arsenic oxide during diffusion in O2 and is not accumulated.
Threshold switching in chalcogenide glass films
Authors: Lee S.H. , Henisch H.K.
Published: January 2004

On the basis of polarization arguments, the equality τd=τl is proposed as the critical condition for the threshold point of chalcogenide glass switches, τd being the dielectric relaxation time and τl the carrier lifetime. It is shown that this switching criterion is in good agreement with measurements and that it explains the temperature dependence of the threshold voltage as well as the voltage dependence of the delay time.
Experimental flux shuttle
Authors: Fulton T.A. , Dunkleberger L.N.
Published: January 2004

We report the operation of an experimental model of the Josephson junction shift register known as the flux shuttle.
Ion-implantation-damage gettering effect in silicon photodiode array camera target
Authors: Hsieh C.M. , Mathews J.R. , Seidel H.D. , Pickar K.A. , Drum C.M.
Published: January 2004

The use of ion implantation damage to getter deleterious impurities from diode space-charge regions is studied. Ion implantation into the neutral regions near p-n junctions is shown to cause substantial reduction in the incidence of the type of white video defects (excessive-leakage current diodes) caused by impurity precipitation and often found in a cyclonic pattern. It is found that using doses of 1016 cm−2 phosphorus (50 keV), ≥1015 cm−2 arsenic (150 keV), and ≥3×1015 cm−2 argon (50 keV) can completely eliminate these defects. In addition, the dark currents of the targets which receive ion implantation is equivalent to or lower than control slices receiving regular phosphorus gettering. From curves of the dark current vs target voltage, it is estimated that the surface recombination velocity (S0) of the ion-implanted slices is ∼20% lower than S0 in the control slices, while the Si–SiO2 interface fixed-charge density is not affected by ion implantation. By comparing the gettering efficiency of P+-, As+-, and Ar+-implanted slices, it is concluded that the damage layer rather than the presence of an implanted n+ region is responsible for the observed gettering behavior.
Pulse amplitude modulation of a CO2 laser in an electro-optic thin-film waveguide
Authors: Cheo P.K.
Published: January 2004

Beam steering of a 10. 6-μm guided-wave mode in an electro-optic GaAs thin-film waveguide is observed. The deflection angle increases linearly with increasing voltage and interaction length. A switching time of about 60 nsec has been obtained and is limited by the detector response. This technique has been used to obtain more than 12% amplitude modulation of a CO2 laser by applying only 50 V to an ∼20-μm-thick GaAs thin-film waveguide having a total interaction length of 0. 5 cm.
Laser-induced gas breakdown in the presence of preionization
Authors: Brown Robert T. , Smith David C.
Published: January 2004

Experiments have been carried out to study the ionization buildup and gas breakdown processes in the focal volume of an intense 10. 6-μ laser pulse in atmospheric-pressure helium preionized to various levels of electron density. With no preionization the laser flux required for breakdown was in agreement with results obtained by previous authors, and showed the same dependence on the focal volume size. However, with a high initial electron density, the threshold was much lower and showed no volume dependence. The results indicate that with preionization the breakdown threshold is controlled by cascade ionization processes, while with no preionization it is dominated by other effects such as small impurity particles in the gas, and that these other effects may be responsible for the diameter dependence of the breakdown threshold.
Submillimeter waveguiding on periodic metal structure
Authors: Ulrich R. , Tacke M.
Published: January 2004

Electromagnetic radiation of 337-μm wavelength has been guided in the form of TM surface waves along thin copper sheets perforated in a regular pattern (metal mesh). Polyethylene prism couplers served for launching and output coupling. The frequency dispersion of the metal mesh guide is similar to that of a transmission line loaded periodically with shunt capacitances. Strong directional dispersion is observed.
Measurement of V-V transfer rate from HF v = 3 using simultaneous optical pumping on the HF v = 2 → 1 and v = 1 → 0 bands
Authors: Osgood R. M. , Sackett P. B. , Javan A.
Published: January 2004

A measurement of the (predominantly) vibration-vibration (V-V) decay rate of the v = 3 level in HF gas yields a value of 1.6×106 sec−1 Torr−1. The technique utilized was to optically pump the HF sample with the output of a pulsed HF laser oscillating simultaneously on a line in both the v = 2 → 1 and v = 1 → 0 bands. An analytic description of the time behavior of the v = 1, v = 2, and v = 3 levels using a treatment based on simplified rate equations is described.
Dislocations in thermally stressed silicon wafers
Authors: Hu S.M.
Published: January 2004

To the author's knowledge, this is the first letter on the dislocation structures generated in silicon wafers by thermal stresses. These dislocations were caused by cooling in a room-temperature ambient on removal from a furnace. The 〈110〉 60° type was dominant, although 〈112〉 dislocations were also observed. Their most important feature is that they tend to seek the shortest allowable paths in passing through the wafer thicknesswise. They often form fairly regular arrays in single or closely neighboring {111} planes, thus producing ensembles of etch pits (or mounds) that macroscopically resemble slip lines. The dislocation densities were often ∼104 cm−2; these values agreed within an order of magnitude with those predicted by a simple stress relief mechanism.
Circular etch pits in ion-implanted amorphous silicon films
Authors: Tu K.N. , Tan S.I. , Crowder B.L.
Published: January 2004

Using a dilute HF solution as the etchant, we found very different etching behaviors between amorphous silicon films prepared by vapor deposition and by ion implantation. The latter are etched preferentially forming circular pits on the surface, but not the former. However, when the evaporated films were subjected to high dosages of ion bombardment and followed by etching, the same kind of circular pits were observed. We conclude that the bombardment of ions can cause weak spots on the amorphous Si surface which possess low resistance to the etching.
cw laser power from carbon bisulfide flames
Authors: Linevsky M.J. , Carabetta R.A.
Published: January 2004

Up to 6 W of cw laser power has been extracted from vibrationally excited CO produced in free-burning CS2/O2/N2O flames burned at pressures of 10–40 Torr. A peak efficiency of approximately one laser photon for every eight fuel molecules has been obtained.
Image recording on FA centered crystals by He–Ne laser
Authors: Shono Y. , Inuzuka T. , Hoshino T.
Published: January 2004

The color centers of type FA in KCl single crystals doped with NaCl or LiCl have been used for image recording by He–Ne laser at room temperature. The optical transmission of the crystals changed linearly with change in the logarithm of incident energy in a certain range. By applying a linearly polarized light beam to anisotropic color centers (FA center), both negative and positive images were obtained from a single stored image.
Generation of 1182-Å radiation in phase-matched mixtures of inert gases
Authors: Kung A.H. , Young J.F. , Harris S.E.
Published: January 2004

Coherent radiation at 1182 Å is obtained by third-harmonic generation in a phase-matched mixture of Xe and Ar. For generation from 3547 to 1182 Å, Xe is negatively dispersive, and phase matching is obtained at a ratio of Xe:Ar=1:430. A conversion efficiency of 2.8% is obtained at an input power of 13 MW. As predicted by theory the conversion efficiency increases linearly to the limit of our available input power.
A new type of magnetic domain wall in nearly compensated Ga-substituted YIG
Authors: Krumme J.-P. , Hansen P.
Published: January 2004

A special type of 180° domain wall which we call a ``compensation wall'' is observed in (111)-oriented wafers with the chemical composition Y3Fe5−tGatO12, where t≈1.3. The compensation wall aligns along the sites of magnetic compensation (Ms=0) normal to the lateral gradient of t and is distinguished from a regular Bloch wall by essentially three properties: (i) The location of the wall remains unchanged under varying external magnetic fields; (ii) the wall thickness depends strongly on the applied magnetic field; and (iii) the wall moves with changing temperature.
Transit-time-limited wall motion in Permalloy films
Authors: Patton Carl E.
Published: January 2004

A simple quantitative formulation of transit-time-limited wall motion is used to show that such an effect can reasonably explain the observed nonlinear wall motion in Permalloy thin films. The ``critical velocity'' is calculated by equating the intrinsic relaxation time Ti to the transit time Tt for the wall past an individual spin position to obtain Vcrit=δ/Ti, where δ is the wall width. The model correctly predicts (i) the magnitude and (ii) variation with film thickness of the observed knee in the velocity-field curves for wall motion in Permalloy films.
Parameter study of a 10-J hydrogen fluoride laser
Authors: Pummer H. , Breitfeld W. , Wedler H. , Klement G. , Kompa K.L.
Published: January 2004

A hydrogen fluoride chemical laser has been constructed with high-voltage pulse initiation in a simple transverse discharge geometry. The system delivers a maximum pulse energy of 11 J with about 100-nsec half-width. This corresponds to an efficiency of nearly 4% with respect to the electrical input into the pulse generator. An investigation of the voltage and the current flow across the discharge chamber, however, indicates that the efficiency with regard to the actual energy deposition in the gaseous discharge is considerably higher. The discharge parameters for optimum operation are discussed.
Vibration-translation rates in CO2 glow discharges
Authors: Gower M.C. , Carswell A.I.
Published: January 2004

V-T rates for the CO2 (1000) and (0001) levels have been measured in various 10.6-μm amplifying and absorbing glow discharges by a simple new technique. The rise and decay times of the changes produced in the discharge current by a short-duration 10.6-μm laser pulse are interpreted in terms of the V-T rates. Reciprocal rise and decay time plots vs pressure yield straight lines, the slopes of which are the average molecular V-T rates for the (1000) and (0001) levels. Provided the electron density is known, the electron deactivation rates for these levels can also be obtained.
Velocity of domain walls in an epitaxial yttrium-europium garnet film
Authors: Vella-Coleiro G.P. , Hagedorn F.B. , Chen Y.S. , Blank S.L.
Published: January 2004

Measurements of magnetic domain velocity by domain transport methods in an epitaxial Y2.4Eu0.6Ga1.2Fe3.8O12 film have yielded values as high as 2800 cm/sec with no sign of saturation. These measurements conflict with those reported recently by Callen et al., who deduced a saturation velocity of 1300 cm/sec from bubble collapse measurements made on films of the same composition. It is suggested that the discrepancy is due to the wall velocity reaching momentarily the Walker breakdown velocity in the bubble collapse technique, which then leads to a relatively immobile spin configuration similar to the one reported recently for hard magnetic bubbles.
Optical waveguiding layers in LiNbO3 and LiTaO3
Authors: Kaminow I.P. , Carruthers J.R.
Published: January 2004

Positive refractive-index layers in LiNbO3 and LiTaO3 have been produced by a novel out-diffusion technique. The index profiles for a variety of conditions are measured directly with an interference microscope. Low-loss optical waveguiding on the surface of these crystals has been observed.
Iron garnet crystals for magneto-optic light modulators at 1.064 μm
Authors: Wemple S.H. , Dillon J.F. , Van Uitert L.G. , Grodkiewicz W.H.
Published: January 2004

Faraday rotation and optical absorption measurements are reported for several magnetic iron garnets. The results show that certain compositions containing praseodymium (or possibly neodymium) should allow the operation of magneto-optic modulators at 1.064 μm, having less than 3 dB of optical loss and requiring less drive power per unit bandwidth than the best available diffraction-limited electro-optic modulators.
Waveguide superradiant dye laser
Authors: Burlamacchi P. , Pratesi R.
Published: January 2004

The characteristics of a superradiant waveguide dye laser are described. Pumping is performed by commercial flashlamps. The output mode pattern was very stable and insensitive to disturbance produced by the dye flow and thermal effects. No recirculation of dye solution is necessary with cooling of the laser head. The superradiant power output is comparable to that of a conventional cavity laser.
UO2 deposition from its plasma
Authors: Kawabuchi Katsuhiro , Magari Saburo
Published: January 2004

When a UO2 anode (hollow cylinder) was sufficiently heated to evaporate by the electron current from a W cathode, a stabilized plasma occurred between the electrodes without feeding any plasma gases. Crystalline UO2 was deposited on the unheated cathode from the plasma. The mechanism of the deposition may be compared to that of electrodeposition of metals and may be called ``electrolysis of plasma''.
Theory and application of two-photon surface effect in infrared photoemission
Authors: Yee Jick H.
Published: January 2004

A study of the theory of the two-beam two-photon surface photoelectric effect, which is based on the steady-state scattering theory, shows that, if the intensities of the two photon beams and the two frequencies are properly chosen, one can use this effect for the detection of the CO2 frequency as well as other infrared frequencies. A numerical example for sodium is presented.
Raman scattering in thin-film waveguides
Authors: Burns G. , Dacol F. , Marinace J.C. , Scott B.A. , Burstein E.
Published: January 2004

It is shown that Raman spectra can be obtained from thin films by using the films as waveguides for the exciting laser light and efficiently collecting the scattered light. We have applied this technique to single-crystal GaN films epitaxially grown on c-plate Al2O3. The measured polarized Raman spectra enable all the Raman active modes to be determined for the GaN (point group C6v).
Optical waveguide modulation using nematic liquid crystal
Authors: Channin D.J.
Published: January 2004

Devices are demonstrated for modulating light in optical waveguides using nematic liquid crystals. 100% modulation and response times of 35 μsec are achieved. Coupling of light into waveguide modes of a liquid layer is demonstrated.
Microwave technique for measuring vibrational temperature in pulsed nitrogen discharges
Authors: Sahni O. , Jennings W.C.
Published: January 2004

A microwave radiometric technique has been developed to measure the molecular vibrational temperature in the active period of a pulsed N2 discharge. The technique monitors decay of the electron average energy Ūe in the afterglow. Kinetic theory analysis shows that if the quasi-steady-state value of Ūe > 0.5 eV, it may be taken as a direct measure of the vibrational temperature Tv in the active period. For lower values of average energy, elastic and rotational energy losses must be included in the calculation of Tv. The results are the first experimental confirmation of the electron-molecular coupling proposed by Hurle.
Thermally stimulated capacitance for shallow majority-carrier traps in the edge region of semiconductor junctions
Authors: Sah C.T. , Walker J.W.
Published: January 2004

The use of the thermally stimulated capacitance (TSCAP) arising from temperature-dependent Fermi level crossing of the trap level in the edge region of a p-n junction is explored as a means of scanning the band gap for shallow-level (60 meV from a band edge) majority-carrier traps above 77°K. An example of the oxygen-vacancy center (186 meV from the conduction band edge) in silicon is given as illustration. The edge region contribution also resolves the anomaly observed in previous applications of the TSCAP method.
Orientation of liquid crystals by surface coupling agents
Authors: Kahn Frederic J.
Published: January 2004

Uniformly oriented thin liquid-crystal layers are required for most liquid-crystal device applications and physical investigations. Usual methods for obtaining orientation rely on a substrate interface which has an orienting action on the liquid-crystal molecules. In previously described methods the orienting interfaces degrade chemically with time, thereby generating a corresponding degradation of the liquid-crystal orientation. In the present work, silane surface coupling agents are used to obtain chemically stable interfaces and a wide variety of liquid-crystal orientations.
Diffuse interface in Si (substrate)-Au (evaporated film) system
Authors: Narusawa T. , Komiya S. , Hiraki A.
Published: January 2004

When a gold film is vacuum evaporated at around 50 °C onto a clean surface of single-crystal silicon substrate, the adhesion of the film to the substrate is very strong, which suggests that some chemical reaction has taken place at the interface. Present study by Auger electron spectroscopy (AES) concludes the occurrence of the above reaction which induces a diffuse interface region in order to relax (or minimize) the interface energy. For the relaxation of silicon (110) and (111) interfaces, at least 45 and 20 monolayers of gold are necessary, respectively. The phase of the thus-formed interface is concluded to be similar to that of the nonequilibrium solid alloy obtained by quenching from a solid Si–Au eutectic liquid.
Very-long-path absorption cell for molecular spectroscopy
Authors: Vali V. , Goldstein R. , Fox K.
Published: January 2004

A method whereby a light beam is temporarily trapped between two retroreflectors was adapted for the use of very-long-path absorption spectroscopy. An absorption path length of 20 km has been obtained with this method. By optimizing all the components for a preselected wavelength band, a path length of the order of 1000 km can be obtained.
Studies of initial oxidation on silicon-iron alloy (100) by means of work function and Auger electron spectroscopy
Authors: Ueda Kazuyuki , Shimizu Ryuichi
Published: January 2004

An initial oxidation process is studied on 5.59 at. % Si–Fe alloy (100) and iron (100) single crystals by the photoelectric work function combined with Auger electron spectroscopy in the low-pressure range of oxygen (10−8−10−6 Torr). A 46-V Auger peak of iron is split into two peaks (41 and 49 V) followed by an oxygen peak as the iron is oxidized. Oxidation at ∼ 10−6 Torr brings about an abrupt increase in the work function in consequence of the chemisorption of oxygen on the sample.
Surface mobility measurement using acoustic surface waves
Authors: Bers A. , Cafarella J.H. , Burke B.E.
Published: January 2004

The sheet mobility of accumulated electrons on silicon has been determined by measuring the acoustoelectric current which accompanies the interaction between these electrons and piezoelectric surface waves on LiNbO3. The advantages of this method are (a) it is a direct mobility measurement (not requiring a knowledge of density), (b) the effect of surface states may be made negligible, (c) it is a zero-average applied-field measurement, (d) both majority- and minority-carrier mobilities may be measured on the same sample. By using high-resistivity (30 000 Ω cm) silicon with an accumulated surface, the sheet density was varied from 1.5×1010 to 5×1011 cm−2. Over this range the mobility was determined to vary from 1100 to 450 cm2/V sec, respectively.
Observation of Raman scattering by SO2 in a generating plant stack plume
Authors: Melfi S.H. , Brumfield M.L. , Storey R.W.
Published: January 2004

Raman scattering by SO2 in an electrical generating plant stack plume has been observed using an optical radar system. Good qualitative agreement is evident between SO2 back-scatter intensity and the plant's electrical power output.
Threshold voltage and ``gain'' term β of ion-implanted enhancement-mode n-channel MOS transistors
Authors: Kamoshida Mototaka
Published: January 2004

Strong dose dependence was observed in the relation between threshold voltage and forward back-gate bias, although in the case of thick depletion layers (reverse back-gate bias) the characteristics showed no dependence of the subsurface concentration. Due to the higher concentration at the subsurface, the gain term β, which decreases with increasing implantation dose, also shows stronger reduction at low field, so that the concave β-vs-field characteristics change to convex curves in the case of higher dose.
High-power broadly tunable difference-frequency generation in proustite
Authors: Decker C.D. , Tittel F.K.
Published: January 2004

High-power wavelength-tunable coherent radiation has been produced by generating the difference frequency between the output from a tunable narrow-linewidth ruby-pumped infrared dye laser and a Q-switched ruby laser in a proustite crystal. Peak infrared powers in the kilowatt range and wavelength tunability from 3.20 to 5.65 μ have been achieved. The experimentally determined infrared power tuning curves are compared to those predicted by theory for interacting Gaussian light beams.
Energy-loss measurements of 4He ions in heavy metals
Authors: Chu W.K. , Ziegler J.F. , Mitchell I.V. , Mackintosh W.D.
Published: January 2004

Energy-loss measurements have been made for 2.0-MeV 4He ions in 20 targets. The energy-loss cross sections were determined by analysis of thick-target backscattering yields. Eight of the targets have been previously measured and support the accuracy of the present measurement. Twelve new heavy-metal targets are evaluated: Pb, Au, Pt, Ir, W, Ta, Hf, Gd, Te, Sb, Mo, and Ge. By using the Lindhard-Winther formalism with Hartree-Fock-Slater atomic charge distributions, the stopping cross sections for these metals are predicted down to 1.4 MeV.
Properties of a high-resistivity layer in epitaxially grown gallium arsenide film
Authors: Okamoto H. , Sakata S.
Published: January 2004

In the high-resistivity layer of vapor-phase epitaxial GaAs films grown under the condition of relatively low arsenic vapor pressure, various interesting properties were found, such as (i) a large PTCR (positive temperature coefficient of resistivity), (ii) large photoconductivity, and (iii) current-controlled negative resistance. A possible explanation is presented.
Heterodyne detection of blackbody radiation
Authors: Gay J. , Journet A. , Christophe B. , Robert M.
Published: January 2004

In order to extend to the infrared range some of the interferometric methods utilized in radioastronomy, the heterodyne detection of 10.6-m blackbody incoherent radiation has been accomplished, and the correlation between detected signals has been studied.
Pulsed HF chemical laser with high electrical efficiency
Authors: Parker J.V. , Stephens R.R.
Published: January 2004

A pulsed HF chemical laser utilizing the chain reaction between H2 and F2 has been operated with electric discharge initiation. A uniform transverse discharge is made possible through the use of spark preionization. For the mixture 1:1:10:0.06 (F2:H2:He:O2) at 120 Torr total pressure an output energy 1.01 times the electrical input has been achieved. The corresponding chemical efficiency was ∼1.0%. A tradeoff is observed between electrical efficiency and chemical efficiency with the maximum chemical efficiency of 2% being achieved at an electrical efficiency of 25%. Even higher electrical efficiencies are expected with further device optimization.
Image forces and the behavior of mobile positive ions in silicon dioxide
Authors: Williams R. , Woods M.H.
Published: January 2004

The electrostatic image force has important effects on the behavior of ions located near an interface. In metallized thin films of SiO2 on silicon the attractive image potential depletes ions from the bulk and localizes them near the interfaces with metal or silicon. For ions localized near the silicon interface, it is shown that a uniform lateral distribution of ions is inherently unstable and tends to condense into patches of high concentration.
Integrated optical photodetector
Authors: Ostrowsky D.B. , Poirier R. , Reiber L.M. , Deverdun C.
Published: January 2004

An optoelectronically integrated photodetector has been realized, consisting of an optical waveguide structure (SiO2-glass) fabricated on an electrically active substrate (Si) containing a photodetector. Light is coupled into the waveguide structure by means of a grating coupler and is guided into the detector element. A coupling efficiency of 80% between the waveguide and detector structure at 6328 Å has been measured.
The effect of dust on 10.6-μm laser-induced air breakdown
Authors: Lencioni D. E.
Published: January 2004

Laser-induced breakdown in very clean air at 10.6 μm is shown to have a threshold of 3 × 109 W/cm2 for large beams and is described well by microwave breakdown theory. Dust particles are shown to lower the threshold by an amount which is greater for larger particles and higher vapor temperatures. There is a minimum in threshold for large particles, which for 200-nsec pulse length is ≤ 108 W/cm2, corresponding to an energy fluence of 10–20 J/cm2. These results are explained qualitatively by the increase in inverse bremsstrahlung rate caused by exploding particles.
Deep trap levels of ion-implanted germanium in silicon measured by Schottky contact techniques
Authors: Schulz M.
Published: January 2004

Differential capacitance measurements on Schottky contacts can be used to determine energy level, charge, and concentration profile of ion-implanted impurities which cause deep trap levels in the semiconducting material. For the example of germanium implanted into silicon, two deep donor levels at Ec − E1 = 0.27 eV and E2 − Ev = 0.51 eV are found which are due to an unstable incorporation of the implanted germanium in the silicon lattice. For the stable incorporation which is obtained at high annealing temperatures, no isoelectronic levels are found for germanium on lattice sites in silicon.
Momentum transfer to laser-irradiated targets, indicating the nonlinear interaction force
Authors: Hora Heinrich
Published: January 2004

Measurements by Metz of the momentum ρ transferred to laser-irradiated targets are evaluated and compared with the results of the nonlinear force of laser-plasma interaction. The measured thresholds for the intensity I*, estimated to be 2 × 1014 W/cm2, agree with the threshold of the nonlinear force. The measured highly superlinear relation P ≈ I4 agrees very well with the theory for not too large intensities I≳ I*. A consequence would be an electron energy of coherent oscillation near 104 eV, which may cause a nonthermal origin of fusion neutrons in other experiments.
Stress compensation in Ga1−xAlxAs1−yPy LPE layers on GaAs substrates
Authors: Rozgonyi G. A. , Panish M. B.
Published: January 2004

Epitaxial layers of Ga0.66Al0.34As1−yPy with y ≤ ≈ 0.04 have been grown in order to demonstrate that it is possible to adjust the lattice parameter of a mixed III-V layer such that it is matched with the GaAs substrate at room temperature. The amount of stress compensation has been determined as a function of y, as well as estimates of the layer thicknesses required to suppress the formation of misfit dislocations.
Self-focusing of laser light in the isotropic phase of a nematic liquid crystal
Authors: Rao D. V. G. L. Narasimha , Jayaraman S.
Published: January 2004

Self-focusing of ruby laser light is studied as a function of sample length and temperature in the isotropic phase of nematic liquid-crystal MBBA. The critical power for self-focusing, 0.36 kW, observed near the phase transition temperature is a factor of 20 times less than that for CS2. The corresponding nonlinear index 4.4 × 10−10 esu is the largest value known so far for any material.
Peaked structure in field-effect mobility of silicon MOS transistors at very low temperatures
Authors: Pals J. A. , van Heck W. J. J. A.
Published: January 2004

Field-effect mobility measurements on silicon n- and p-channel MOS transistors at temperatures of 4.2 K and lower are reported. The measured field-effect mobility as a function of the gate voltage shows an anomalous peaked structure superimposed on the well-known over-all behavior. These peaks are possibly due to statistical fluctuations within the bands of the semiconductor of the density of surface states as a function of the energy.
Electron-beam-initiated chemical laser in SF6–H2 mixtures
Authors: Gross Rolf W. F. , Wesner F.
Published: January 2004

A 3.5-cm × 35-cm planar field emission electron beam diode, producing a total beam current of 4.65 kA of 120-keV electrons in 26-nsec pulses was used to initiate the reaction of F with H2 in SF6–H2 mixtures. From an optical volume of approximately 1 liter we observed HF laser pulses of 20–30 nsec duration with a maximum energy of 0.2 J at 450 Torr. The application of a secondary potential, very near the self-breakdown limit of the gas, to the laser medium increased the laser output by only a factor of 2. Numerical analysis of the experiments without secondary field shows that 2.7 × 104 F atoms are produced by each 120-keV electron fully stopped in the gas. This corresponds to an energy of 4.5 eV required for the production of one F atom from SF6 by high-energy electrons. The conversion efficiency of electron beam energy input to the medium to laser output energy was 5.2%.
Continuously tunable high-pressure CO2 laser with uv photopreionization
Authors: Alcock A. J. , Leopold K. , Richardson M. C.
Published: January 2004

The operation of a uv photoinitiated tranverse-discharge CO2 laser has been investigated at pressures up to 15 atm. Preliminary studies of a device having an active volume of [inverted lazy s] 13 cm3 have yielded a maximum output of [inverted lazy s] 1 J in 30 nsec, while the use of a grating-tuned resonator has resulted in continuously tunable operation over frequency intervals of [inverted lazy s] 20 cm−1.
HF and DF lasers by direct electrical discharge excitation
Authors: Byron S. R. , Nelson L. Y. , Mullaney G. J.
Published: January 2004

Using a high-current long-pulse electron-beam-stabilized electrical discharge, laser oscillation has been observed on several vibration-rotation bands of HF and DF in mixtures containing less than 1% HF or DF. Results in HF/argon mixtures with 10% added N2, H2, or D2 established that HF is vibrationally pumped by direct electron impact and also by vibrational energy transfer from H2. Rotational nonequilibrium as well as cascade coupling between 3 → 2 lines and 2 → 1 lines were inferred from the time sequence of the laser emission.
Saturated resonance spectroscopy of SiF4
Authors: Nella John
Published: January 2004

The small-signal absorption coefficient of silicon tetrafluoride (SiF4) at the 9.6-μm CO2 laser wavelength has been measured by means of saturated spectroscopy. The Lamb dip spectrum of the SiF4 transitions in coincidence with five CO2 9.6-μm P-branch transitions has been observed. Measurements of the pressure dependence of the Lamb dip width were made, resulting in a determination of the SiF4–SiF4 cross section for phase interruption collisions. The saturation intensity was experimentally found to be quadratic with pressure, in a limited pressure range, and an upper bound for the Einstein A coefficient was determined.
Electronically focused acoustic imaging device
Authors: Havlice J. F. , Kino G. S. , Quate C. F.
Published: January 2004

A new type of acoustic imaging device, which scans a large array of piezoelectric detectors is described. Scanning is carried out by a signal traveling along an acoustic surface wave delay line. The device can be electronically focused, and has given images of objects 20 cm from the detector array, illuminated with a 5-MHz acoustic wave, with a definition of 1 mm.
Effect of crystal structure on diffusion broadening of Mössbauer line shape in polycrystalline samples
Authors: Dibar-Ure M. Celia , Flinn Paul A.
Published: January 2004

Experimental observations of diffusional broadening of the Mössbauer resonance in polycrystalline solids have generally been analyzed on the basis of a liquidlike model which neglects the restriction of atomic jumps to crystallographically determined directions. A calculation based on the theoretical results of Chudley and Elliot for single crystals, averaged over all directions, shows that a substantial correction to the liquidlike result is required. Application of this correction, along with a simple assumption about the correlation factor largely eliminates the existing discrepancies between theory and experiment.
Electronic control of the velocity and attenuation of surface acoustic waves in piezoelectric semiconductors
Authors: Ganguly A. K. , Chao G.
Published: January 2004

The velocity and attenuation of a surface acoustic wave on a piezoelectric semiconductor may be controlled by adjusting the bias of a reverse-biased distributed diode. With the proper choice of resistivity and operating frequency, changes in velocity of 1% and attenuation of 300 dB/cm may be achieved in c-axis cadmium sulfide for bias voltages under 30 V. Theoretical behavior is presented and initial experimental results are summarized.
Effects of lattice disorder on the intrinsic optical damage fields of solids
Authors: Fradin D. W. , Bass Michael
Published: January 2004

Measurements of the effects of polycrystallinity and lattice disorder on the intrinsic laser-induced damage fields of transparent solids are reported. Extreme lattice disorder such as present in a highly amorphous material such as fused quartz causes the damage field to increase, whereas less severe disorder does not measurably affect the breakdown strength. This is consistent with an electron avalanche intrinsic damage mechanism.
Compensation from implantation in GaAs
Authors: Davies D. Eirug , Kennedy J. K. , Yang A. C.
Published: January 2004

Non-dopant ions have been implanted at low doses ([inverted lazy s] 1010 cm−2) into GaAs to determine the extent of carrier removal and to pin-point annealing stages for carrier recovery. A removal rate of around 200 carriers per ion is found for such lighter ions as B+, N+, and F+. At the 1-MeV energy used, compensating damage extends along the ion track right from the GaAs wafer surface. Partial recovery of the carriers as well as mobility occurs at the well-known 225 °C electron damage annealing stage. A further annealing stage is found at [inverted lazy s] 525 °C.
Detection and generation of magnetic bubble domains using ferrimagnetic resonance
Authors: Dötsch Horst , Schmitt Hans Jürgen , Müller Jürgen
Published: January 2004

Ferrimagnetic resonance within the bubble layer is used to couple two microwave transmission lines. If a bubble is switched into the coupling region which is comparable in size with a bubble domain, the transmitted microwave signal changes. For a 5-μm bubble a Zero/One ratio of 6:1 has been obtained. It is also possible to influence the resonance transmission in a reference layer adjacent to the bubble layer by the magnetic stray field of a bubble. At high power levels a nonlinear interaction between the microwaves and the magnetic domains is observed which can be used for bubble generation.
Proton-implanted optical waveguide detectors in GaAs
Authors: Stoll H. , Yariv A. , Hunsperger R. G. , Tangonan G. L.
Published: January 2004

Defect levels introduced by implanting GaAs with high-energy protons give rise to optical absorption at wavelengths greater than that of the normal absorption edge at 0.9 μ. Optical waveguide detectors may be fabricated by taking advantage of this absorption mechanism in the presence of a Schottky barrier depletion layer. Detector response times less than 200 ns and external quantum efficiencies of 16% have been observed.
Photodiodes fabricated in epitaxial PbTe by Sb+ ion implantation
Authors: Donnelly J. P. , Holloway H.
Published: January 2004

Photodiodes in thin films of epitaxial PbTe grown on BaF2 have been fabricated using Sb+ ion implantation to create an n-type layer in p-type films. At 77 °K, 15-mil-square diodes had typical zero-bias resistances of 1 MΩ. With the infrared radiation incident on the n-type implanted layer, peak detectivities at 5.3 μm of 4.5 χ 1011 cm Hz1/2/W were observed in reduced background. Quantum efficiencies were typically 55%. With the radiation incident on the p-type side through the BaF2 substrate, the detectivity was much more sharply peaked with the peak occurring at 5.5 μm. The peak detectivity and quantum efficiency values in this case were similar to those for incidence on the n-type implanted layer.
cw submillimeter laser generation in optically pumped Stark-tuned NH3
Authors: Fetterman H. R. , Schlossberg H. R. , Parker C. D.
Published: January 2004

Submillimeter laser action has been achieved in ammonia by Stark shifting vibrational absorption lines into resonance with a CO2 laser pump. In two of the three observed cases the absorption line was between states of the same parity, i.e., forbidden in the absence of the applied Stark field. Stark tuning of a vibrational absorption into resonance with a pump laser line is a general technique which should greatly increase the number of stable cw submillimeter lines available at milliwatt power levels.
X-ray point-source projection photography with a laser-produced source
Authors: Holzrichter J. F. , Dozier C. M. , McMahon J. M.
Published: January 2004

Laser-produced plasmas are shown to have characteristics useful for high-resolution subnanosecond x-ray radiography. Plasmas produced by 3-J subnanosecond 1.06-μm laser pulses focused onto an Al target emit x rays (≳ 1.5 keV) from a 50-μm-diam volume in the order of 1 nsec. Such sources may be useful to probe other plasmas.
Staging of theta pinches using laser-heat addition and magnetic compression
Authors: Hoffman Alan L. , Vlases George C.
Published: January 2004

The thermodynamics of using laser heating in conjunction with magnetic compression in θ-pinch plasmas is discussed. It is shown that the minimum laser energy required to achieve a given plasma filling factor Λ (ratio of plasma to plasma tube area) is Elaser = Λ2/3Eplasma and that any filling factor up to Λ = 1 can be achieved. The proposed schemes have important implications for either increasing the performance of standard θ pinches or for replacing the single-turn θ-pinch coil by a multiturn solenoid.
Strong axial laser heating of a theta-pinch plasma
Authors: Hoffman Alan L.
Published: January 2004

Holographic interferograms are shown of θ-pinch plasmas heated axially by 35 J of 10.6-μm radiation. One hundred percent conversion of laser to plasma thermal energy is indicated by the resultant plasma expansion and inferred temperature increase from 10 to 65 eV. The heated plasma column is 10 cm long by 6 mm in diameter and at an electron density of about 5 × 1017 cm−3. The laser heating process is seen to produce a self-trapping density minimum on axis in contrast to the density maximum encountered in normal unheated θ pinches. This has significant implications for the high-density laser-heated long-solenoid approach to fusion.
Temperature dependence of the lasing transition in high-purity GaAs
Authors: Chinn S. R. , Rossi J. A. , Wolfe C. M.
Published: January 2004

We have measured the lasing energy of optically pumped high-purity GaAs from 2 to 300 K. Low-temperature results show strong many-body effects in the band-to-band lasing below the single-particle band-gap energy, and the high-temperature data indicate that the lasing energy approaches the band gap measured by photoconductivity.
Refractive index measurements on magnetic garnet films
Authors: McCollum B. C. , Bekebrede W. R. , Kestigian M. , Smith A. B.
Published: January 2004

Refractive-index-versus-wavelength data were determined from 509 to 633 nm for a number of bubble memory rare-earth garnet films. Using these data, the film thickness of these materials can be determined with an accuracy of 1–1.5%.
Direct infrared image up-conversion with a praseodymium chloride quantum counter
Authors: Sewell Kenneth G. , Volz William B.
Published: January 2004

Infrared images at 1.48, 1.59, 2.05, 2.38, and 4.81 μm have been successfully up-converted to 645.2 nm by using a PrCl3 quantum counter. Maximum up-converted resolution is 2.92 line pairs/mm, equal to that of the projected image, for an optical pump intensity of 2 mW/cm2 on a 0.63-cm format. A quantum efficiency of 4.6 × 10−6 has been measured for a device temperature of 163 °K and an optical pump intensity of 8 mW/cm2. The variation in 645.2-nm fluorescence with temperature is explained in terms of a depopulation mechanism involving thermal excitation to levels higher than 3P0.
Generation of tunable far-infrared radiation by difference frequency mixing using conduction electron spin nonlinearity in InSb
Authors: Bridges T. J. , Nguyen Van Tran
Published: January 2004

Far-infrared radiation tunable between 93 and 100 cm−1 has been produced by difference frequency mixing between the 944.2-cm−1 pump and the tunable frequency-shifted Stokes radiation from an InSb spin flip Raman (SFR) laser. Mixing occurs in a separate crystal of InSb using the strong nonlinearity of the electron spins. Since operation of both SFR laser and mixer require the same geometry and magnetic field, they are mounted together in the superconducting magnet.
Bulk acoustic wave interaction with guided optical waves
Authors: Brandt G. B. , Gottlieb M. , Conroy J. J.
Published: January 2004

An interaction between longitudinal or shear bulk acoustic waves and guided optical waves has been observed in single-mode and multimode polyurethane and sputtered glass optical waveguides. This interaction produces a number of effects — namely, mode conversion, amplitude modulation, and phase modulation — depending upon whether shear or longitudinal sound is present. Mode conversion between TE and TM waveguide modes occurs with shear sound; longitudinal sound produces amplitude and phase modulation of the guided light. The bulk acoustic wave effect offers promise for producing high-data-rate integrated optical modulators.
Acoustic surface wave properties of epitaxially grown aluminum nitride and gallium nitride on sapphire
Authors: O'Clock G. D. , Duffy M. T.
Published: January 2004

Experimental results are reported on the coupling of rf energy and acoustic surface waves in aluminum nitride (AlN) on sapphire and gallium nitride (GaN) on sapphire material systems. Metallized interdigital transducers are deposited on the AlN and GaN surfaces to generate and detect the acoustic surface wave energy.
New electrochromic memory display
Authors: Schoot C. J. , Ponjee J. J. , van Dam H. T. , van Doorn R. A. , Bolwijn P. T.
Published: January 2004

The principle of a new electrochromic display based on an oxidation-reduction reaction of an organic compound of the viologen family is described. The result is a display having a built-in memory, high contrast, a low switching voltage, and a low mean power consumption.
Lasing from the upper vibrational levels of a flash-initiated H2–F2 laser
Authors: Suchard S. N.
Published: January 2004

Laser action has been observed from the P-branch vibration-rotation bands of the HF molecule from v = 6→5 to v = 1→0 transitions. In addition, the time-resolved spectral behavior of this He-diluted H2–F2 chain reaction chemical laser has been recorded. The HF* lasing molecules were produced by the reaction of a 50-Torr gaseous mixture with mole ratio H2/F2/He=0.5/1/40 initiated by flash photolysis. In contrast to earlier results, strong lasing was found on the v = 6→5 and 5→4 transitions of the HF molecule. Within some of the bands from which lasing was observed, the time sequencing of transitions suggests non-Boltzmann distributions of the rotational states.
Copper superradiant emission from pulsed discharges in copper iodide vapor
Authors: Liu C. S. , Sucov E. W. , Weaver L. A.
Published: January 2004

Superradiant copper laser emission at 5106 and 5782 Å is reported from pulsed discharges in copper iodide vapor at temperatures of about 600°C. Dissociation of the iodide, excitation of the copper atom, and resonance trapping of the 3248 Å copper transitions are proposed as the principal inversion mechanisms.
Laser emission at 3 μ from Dy3+ in BaY2F8
Authors: Johnson L. F. , Guggenheim H. J.
Published: January 2004

A unique combination of properties in the host crystal BaY2F8 has made it possible to obtain laser emission from the Dy3+ ion at 3.022 μ. The laser line lies close to the electronic transition from the lowest level of the 6H13/2 excited state at 3520 cm−1 to a ground manifold level at 216 cm−1, but the oscillation frequency is shifted by 5 cm−1 due to overlapping vibronic lines. The intensity of Dy3+ emission is enhanced by energy transfer from Er3+, Yb3+, Tm3+, and Ho3+. The restrictions imposed on the multiphonon decay rates for the operation of a Dy3+ laser at 3 μ are discussed. A comparison of radiative and nonradiative relaxation rates for rare-earth ions in BaY2F8 indicates that an extension of laser emission to beyond 4 μ is unlikely.
Characteristics of aluminum-titanium electrical contacts on silicon
Authors: Bower Robert W.
Published: January 2004

An aluminum-titanium metallization scheme for use in silicon integrated circuits is described. This metallization can produce high-conductance electrical contacts with negligible dissolutions of silicon. The desirable contact is lost, however, if a TiAl3 reaction product is allowed to consume the entire Ti layer. The TiAl3 forms during the postmetallization heat treatment used to stabilize the electrical characteristics of the contact. The Ti layer is found to be consumed in this reaction at a rate proportional to t1/2, where the rate constant is determined to be d=d0 exp(−Ea/kT), where d0 ≈ 0.15 cm2/sec and Ea ≈ 1.85 eV. This rate constant can be used to determine the thickness of titanium layer necessary to produce the desirable electrical contact.
cw monolithic acoustic surface wave amplifier incorporated in a Δv/v waveguide
Authors: Coldren L. A. , Kino G. S.
Published: January 2004

Room-temperature cw operation is reported for an acoustic surface wave amplifier which uses a 25-μm-wide thin film of InSb deposited on LiNbO3. The device also illustrates the use of a thin semiconductor or metal film as a waveguiding structure which exhibits very little dispersion. A cw gain of 23 dB was observed at 340 MHz with a group delay factor (1/τ)∂τ/∂f = −8.3 × 10−7 MHz−1.
Transmission of stationary nonlinear optical pulses in dispersive dielectric fibers. I. Anomalous dispersion
Authors: Hasegawa Akira , Tappert Frederick
Published: January 2004

Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion. In the case of anomalous dispersion (∂2ω/∂k2>0) discussed here [the case of normal dispersion (∂2ω/∂k2<0) will be discussed in a succeeding letter], the stationary pulse is a ``bright'' pulse, or envelope soliton. For a typical glass fiber guide, the balancing power required to produce a stationary 1-ps pulse is approximately 1 W. Numerical simulations show that above a certain threshold power level such pulses are stable under the influence of small perturbations, large perturbations, white noise, or absorption.