bluuebunny/crossref_metadata_2025 huggingface dataset:
New dry etch for Al and Al-Cu-Si alloy: Reactively masked sputter etching with SiF4
Authors: Horwitz Chris M.
Published: February 2003

A new technique, ‘‘reactively masked sputter etching’’ of Al, is described here. This process can pattern fine lines in Al or in Al-Cu-Si alloy but does not have many of the problems associated with presently available reactive sputter etching methods. The technique combines deposition and etching in the one process; Al2O3, Al, and Al-Cu-Si alloy are etched, while all other materials are coated with a layer of SiOx. This results in essentially infinite (Al/mask) and (Al/substrate) etch rate ratios. In addition, the etch gas contains no Cl, which is a common cause of corrosion and undercut. In effect, the etch combines the advantages of both reactive and nonreactive sputter etching. The gas described here is a SiF4/O2 mixture, and it is shown that additions of most impurity gases have very little effect on the etch. However, water or H2 addition significantly improves the performance of the etch, and typical profiles are shown for a SiF4/O2/H2 mixture with a photoresist masking layer.
Viologen-based electrochromic light scattering display
Authors: Barclay D. J. , Dowden B. F. , Lowe A. C. , Wood J. C.
Published: February 2003

In conventional viologen-based electrochromic displays, contrast changes are achieved by modulating light using the optical absorbance of the electrodeposited film. A display technique is described which uses instead the light scattering properties of the same film to produce intensity variations. Under practical conditions, contrast ratios of 60:1 can be achieved by electrodepositing 1 mC cm−2 of the n-heptyl viologen cation radical with a 1-ms current pulse. The display also has memory and is compatible with integrated drive schemes.
Drift velocity measurements in relativistic electron beams
Authors: Avivi P. , Cohen Ch. , Friedland L.
Published: February 2003

A novel experimental method to measure the average drift velocity of relativistic electron beams is presented. The method is based on simultaneous measurements of the beam current and the radial electrostatic potential induced by the space charge of the beam. The method was applied to analyze the beam at different diode voltages and guide fields. The average drift velocity was found to be always considerably less than that corresponding to the diode voltage.
Pd/a-Si:H metal-insulator-semiconductor Schottky barrier diode for hydrogen detection
Authors: D’Amico A. , Fortunato G. , Petrocco G. , Coluzza C.
Published: February 2003

Hydrogenated amorphous silicon (a-Si:H), produced by the glow-discharge technique, has been used to construct very low cost, high quality metal-insulator-semiconductor structures where palladium has been utilized as catalytic metal for hydrogen detection. With this device, hydrogen concentration in hydrogen-nitrogen mixture as low as 100 ppm has been detected. There is indication that the ultimate limit is much lower.
High-performance K-band GaAs power field-effect transistors prepared by molecular beam epitaxy
Authors: Saunier P. , Shih H. D.
Published: February 2003

The maturity of the molecular beam epitaxy (MBE) technique for preparing device quality GaAs material for microwave applications is demonstrated by the excellent performance characteristics of K-band GaAs power field-effect transistors (FET’s) fabricated on the MBE wafers. An output power of 710 mW with 4.5-dB gain and 17.7% power-added efficiency was achieved at 21 GHz with a 1.26-mm gate width π-gate device. A similar device with a 0.56-mm gate width produced an output power of 320 mW with 5.0-dB gain and 26.6% power-added efficiency at 21 GHz. These are the best results yet reported to date for GaAs power FET’s operated in the K-band frequency range.
High resistivity in p-type InP by deuteron bombardment
Authors: Focht M. W. , Schwartz B.
Published: February 2003

High resistivity layers have been achieved in p-type InP using deuteron bombardment. A curve of average resistivity versus bombardment dose has been determined for p-type InP with an initial background carrier concentration of 1×1018 cm−3. It has been shown that average resistivities of 109 Ω cm or higher can be attained reproducibly, over a dose range 3×1013–1×1014 deuterons/cm2.
Thermoelastic hologram for focused ultrasound
Authors: von Gutfeld R. J. , Vigliotti D. R. , Ih C. S. , Scott W. R.
Published: February 2003

An acoustic holographic lens structure is described for generating thermoelastic waves from the energy of absorbed laser excitation. The structure uses a large area optically absorbing surface to permit the megahertz ultrasound to be focused for nondestructive evaluation applications. Experimental results for the spatial distribution of 10-MHz ultrasonic waves obtained from the hologram are presented.
Solid phase epitaxial regrowth of amorphous silicon on molecular beam epitaxial silicon/Si layers
Authors: Christou A. , Wilkins B. R. , Davey J. E.
Published: February 2003

The recrystallization and epitaxial regrowth of amorphous silicon layers on molecular beam epitaxial (MBE) silicon at 650 °C is described. MBE silicon layers were deposited at 650 °C followed by deposition of amorphous layers at 100–400 °C. Subsequent solid phase epitaxial regrowth of these layers has been achieved at 650 °C.
Solid phase diffusivity effect on nonequilibrium dopant segregation
Authors: Campisano Salvatore Ugo , Baeri Pietro
Published: February 2003

The profile distribution and lattice location of Zn atoms after laser irradiation of ion implanted Si and Ge substrates have been determined by ion beam analysis techniques. In Si the implanted Zn is completely zone refined to the surface whilst in Ge considerable trapping and supersaturation are obtained. Zn is a fast interstitial diffuser in Si and a slow substitutional diffuser in Ge. This result confirms the kinetic trapping model in which the solid phase diffusivity of the considered dopant plays an important role in determining the velocity at which the interfacial segregation coefficient deviates from the equilibrium value.
High performance hydrogenated amorphous silicon solar cells made at a high deposition rate by glow discharge of disilane
Authors: Ohashi Yutaka , Kenne Jean , Konagai Makoto , Takahashi Kiyoshi
Published: February 2003

The deposition rate, electronic and optical properties of hydrogenated amorphous silicon films prepared from rf glow discharge decomposition of disilane (Si2H6) diluted in helium have been measured. These films show excellent electrical and optical properties and, most importantly, a high deposition rate coupled with satisfactory solar cell application was realized for the first time. At a deposition rate of 11 Å/s, 5.47% and 6.5% conversion efficiencies were obtained with a first trial of n-i-p type solar cells deposited on SnO2/ITO glass and metal substrates, respectively.
Silicon molecular beam epitaxy on gallium phosphide
Authors: de Jong T. , Douma W. A. S. , van der Veen J. F. , Saris F. W. , Haisma J.
Published: February 2003

Si overlayers have been grown under ultrahigh vacuum conditions on GaP(100) single crystals by means of molecular beam epitaxy. For growth temperatures of 300 °C and higher (2×1) low-energy electron diffraction patterns of the Si overlayers were seen at all overlayer thicknesses produced (8–10 000 Å). By means of Auger electron spectroscopy segregation of P and Ga on top of the grown Si surface was measured. With Rutherford backscattering using ion channeling we found Si minimum channeling yields of 3% in the GaP:Si(100) heterostructures, which corresponds well to the yield of pure monocrystalline (100) Si. Two methods are described to eliminate the Ga and P segregation.
Shot noise effect on the nonzero voltage state of the hysteretic Josephson junction
Authors: Ben-Jacob E. , Bergman D. J. , Imry Y. , Matkowsky B. J. , Schuss Z.
Published: February 2003

We consider the combined effect of shot and thermal noise on (i) the stationary distribution of fluctuations about the nonzero voltage state of an underdamped hysteretic Josephson junction, and (ii) the noise induced transition rate from the nonzero voltage to the zero voltage state. We find that the distribution is nonsymmetric in that the positive voltage fluctuations are more probable than the negative ones. We also find that the transition rates are larger than those due to thermal noise alone.
Direct measurement of the carrier leakage in an InGaAsP/InP laser
Authors: Chen T. R. , Margalit S. , Koren U. , Yu K. L. , Chiu L. C. , Hasson A. , Yariv A.
Published: February 2003

Carrier leakage over the heterobarrier in an InGaAsP/InP laser is measured directly in a laser-bipolar-transistor structure. Experimental results indicate a significant amount of carrier leakage under normal laser operating conditions.
Stimulated bremsstrahlung masers
Authors: Palmer A. J.
Published: February 2003

Interferometer measurements of the dielectric constant of the cathode-region plasma of a helium glow discharge yield a null result for the stimulated bremsstrahlung gain coefficient for 75–95-GHz radiation in contradiction to recently reported single-pass gain measurements. Physical arguments supportive of the results are presented.
Picosecond optical pulse generation by impulse train current modulation of a semiconductor laser
Authors: Elliott R. A. , DeXiu Huang , DeFreez R. K. , Hunt J. M. , Rickman P. G.
Published: February 2003

Optical pulses of less than 10-ps duration have been generated by driving a GaAlAs laser with a train of 80-ps full width at half-maximum current impulses and a 20-ns pulsed square wave bias.
2.5-THz frequency difference measurements in the visible using metal-insulator-metal diodes
Authors: Drullinger R. E. , Evenson K. M. , Jennings D. A. , Petersen F. R. , Bergquist J. C. , Burkins Lee , Daniel H.-U.
Published: February 2003

Using point-contact metal-insulator-metal diodes, we have demonstrated heterodyne detection of visible laser radiation at frequency differences up to 2.5 THz (generated by a 119-μm laser). The signal to noise on the observed rf beat falls off at 2.3 dB/octave of laser frequency difference and would seem to indicate that 30-THz difference beats will be obervable with improved laser stability or signal averaging. While the diode detector ‘‘bandwidth’’ per se has not been evaluated, these measurements demonstrate an increase in the frequency difference which can be measured in the visible by more than an order of magnitude over that previously reported.
Polarized fluorescence line narrowing measurements of Nd laser glasses: Evidence of stimulated emission cross section anisotropy
Authors: Hall D. W. , Weber M. J.
Published: February 2003

Polarized 4F3/2→4I11/2 and 4F3/2→4F9/2 emission of Nd3+ in silicate laser glasses are measured using resonant and nonresonant fluorescence line narrowing techniques. The observed depolarization ratio is a measure of the anisotropy of the stimulated emission cross section and the degree of polarization hole burning that will occur for lasers operating in the large-signal gain regime.
Point-source x-ray backlighting for high-density plasma diagnostics
Authors: Miyanaga M. , Kato Y. , Yamanaka C.
Published: February 2003

We have developed a new backlighting method which uses a point x-ray source. It has the advantages of a large magnification factor, high spatial resolution, and freedom from the source intensity nonuniformity. Initial test results and evaluation of this method in comparison with other methods are presented.
Photovoltaic properties of cadmium sulfide/trivalent-metal phthalocyanine heterojunction devices
Authors: Hor Ah-Mee , Loutfy Rafik O. , Hsiao Cheng-Kuo
Published: February 2003

Thin-film photovoltaic devices consisting of a CdS/trivalent-metal phthalocyanine heterojunction have been prepared. The devices are fabricated by first electrodepositing a thin film of CdS onto a transparent conducting indium-tin-oxide substrate and then depositing phthalocyanine and gold layers sequentially in a vacuum coater. The trivalent-metal phthalocyanines used are chloroaluminium chlorophthalocyanine (ClAlClPc), chloroaluminium phthalocyanine (ClAlPc), and chloroindium phthalocyanine (ClInPc). Under an AM2 illumination of 75 mW cm−2, these heterojunction devices produce an open-circuit voltage Voc of 0.70 V and short-circuit current Jsc of 0.8 mA cm−2. The conversion efficiency is about 0.2%, which represents one of the highest values reported for phthalocyanine photovoltaic devices at high light intensity.
Transversely excited Sr+ recombination laser
Authors: Brandt M.
Published: February 2003

Operation of a strontium-ion recombination laser in a transverse-discharge configuration is reported. Laser oscillation occurred on the 431-nm transition of Sr+ over a range of discharge parameters, including He gas pressure up to 200 kPa (1500 Torr). Output energy densities of 25 μJ/cm3 have obtained from an active volume of approximately 40 cm3.
Picosecond frequency chirping and dynamic line broadening in InGaAsP injection lasers under fast excitation
Authors: Lin Chinlon , Lee T. P. , Burrus C. A.
Published: February 2003

We report the first observation of picosecond time-resolved frequency chirping within each longitudinal mode of InGaAsP injection lasers under fast excitation. This transient phenomenon is responsible for the characteristic dynamic line broadening observed in the spectra of injection lasers under modulation. The frequency chirping invariably shows a ‘‘red shift’’ during the optical pulse, and is associated with the refractive index increase due to the carrier density decrease in the process of optical pulse generation. The dynamic line broadening will limit the single-mode fiber transmission bandwidth even when single-longitudinal-mode injection lasers are used.
Photoelectrochemical deposition of metals onto p-silicon using an internal cell
Authors: Rose T. L. , Longendorfer D. H. , Rauh R. D.
Published: February 2003

Spatially defined photoelectrochemical deposition of low work function metals onto p-Si has been observed, operating through the local cell M+n+ne−→p-SihνM° ←dark Some M° must be incorporated initially onto the Si surface via a low resistance contact. With M=Zn or Cd, a large band bending is induced at the semiconductor/plating electrolyte junction, resulting in highly efficient imaging. For the more noble metals, Cu and Ni, the bending is very small or nonexistent, and this kind of imaging is not observed.
Time-resolved x-ray diffraction measurement of the temperature and temperature gradients in silicon during pulsed laser annealing
Authors: Larson B. C. , White C. W. , Noggle T. S. , Barhorst J. F. , Mills D. M.
Published: February 2003

Nanosecond resolution time-resolved x-ray diffraction measurements have been used to study the temperature and temperature gradients in 〈100〉 and 〈111〉 oriented silicon crsytals during pulsed laser annealing. Thermal strain analysis of time-resolved extended Bragg scattering has shown the lattice temperature to reach the melting point during 15-ns, 1.5-J/cm2 ruby laser pulses and to remain at the melting point during the high reflectivity phase (HRP). The temperature gradients at the liquid-solid interface were found to be in the range of ∼107 K/cm during the HRP.
Determination of grain boundary barrier height and interface states by a focused laser beam
Authors: Poon E. , Yang E. S. , Evans H. L. , Hwang W. , Osgood R. M.
Published: February 2003

An experimental technique has been developed to study the electrical properties of semiconductor grain boundaries (GB’s) by a focused laser beam. The laser beam is trained on a GB while the photoconductivity of the sample is measured. This technique allows us to examine a localized region of an individual GB in semiconductors with multiple grains. The measurement of the steady state and transient signals as a function of temperature determines the grain boundary barrier height, trap energy, and capture cross section.
Effect of high doping on the photoluminescence edge of GaAs and InP
Authors: Bendapudi Seishu , Bose D. N.
Published: February 2003

A theoretical method for calculating the variation of optical transition energy Eg,opt in semiconductors with heavy n doping is presented. The calculations based on the Moss–Burstein shift and band-gap shrinkage take into account both exchange and Coulomb interactions, the latter being calculated for nonparabolic bands. A comparison with the experimental values of Eg,opt for heavily n-doped GaAs and InP shows good agreement over wide ranges of temperature and doping and can satisfactorily explain photoluminescent emission at energies up to 1.65 eV in GaAs (1.8 °K) and 1.91 eV in InP (300 °K).
Intermittency in Josephson junctions
Authors: Yeh W. J. , Kao Y. H.
Published: February 2003

Numerical and analog solutions to a differential equation describing an rf-driven Josephson junction were obtained; variations of the quantum phase difference across the junction and its time derivative provide clear examples for the existence of intermittency in this nonlinear system. A critical exponent is determined in agreement with theoretical predictions.
Stimulated emission in strained GaAs1−xPx-GaAs1−yPy superlattices
Authors: Ludowise M. J. , Dietze W. T. , Lewis C. R. , Holonyak N. , Hess K. , Camras M. D. , Nixon M. A.
Published: February 2003

Photoluminescence data are presented on a direct-well GaAs1−xPx-GaAs (x∼0.25) strained superlattice (SL) (barrier LB ∼75 Å, quantum well Lz∼75 Å) and on indirect-well GaP-GaAs1−xPx (x∼0.6) strained SL’s (LB, Lz∼120 Å and LB, Lz∼60 Å) grown by organometallic vapor phase epitaxy. Stimulated emission (at 300 and at 77 K) is observed in the former but only weak luminescence in the latter, thus establishing that a large density of defects at the heterointerfaces is not necessarily an issue in strained SL’s and that so far zone-folding effects, and SL ‘‘indirect-direct’’ conversion, have not been observed in indirect systems.
Laser implosion of thick low-Z foam coated glass microballoon
Authors: Okada K. , Mochizuki T. , Sakabe S. , Shiraga H. , Yabe T. , Yamanaka C.
Published: February 2003

Driving pressure uniformity on the pusher surface has been significantly improved using a thick low density foam coated pellet with 120-ps laser pulse irradiation. The pusher surface is geometrically kept at 100 μm from the laser absorption region. The hydrodynamic converging mechanism in the foam medium may be responsible for the observed smoothing.
Abel inversion with a simple analytic representation for experimental data
Authors: Deutsch Moshe
Published: February 2003

The advantages of using a simple analytic representation for experimental data requiring Abel inversion are explored. A simple yet versatile function is proposed, and its Abel inverse derived. Its use allows not only a fast and accurate inversion of the data but also a simple, straightforward calculation of the magnitude of the error in the inverted values in terms of the mean standard deviations of the parameters defining the proposed function. A full discussion of the sources of error and their relative importance is also presented, as well as a numerical example using simulated data. The analysis indicates that unless the measured data is error free to an extremely high degree, no amplification of the experimental error, inherent in the data, occurs with this inversion method even if only three or four adjustable parameters are employed in defining the analytic function.
Observation of relaxation resonance effects in the field spectrum of semiconductor lasers
Authors: Vahala K. , Harder Ch. , Yariv A.
Published: February 2003

Subsidiary maxima are observed in the field spectra of single mode semiconductor lasers. Measurements of their power dependence show they are linked to the relaxation resonance. We attribute these maxima to combined phase and amplitude fluctuations at the relaxation resonance. A theoretical calculation of the field spectrum using the results of a noise analysisincorporating carrier dynamics agrees very well with observations.
Photolysis of KI/Xe mixtures at 193 nm: Observation of KXe* emission
Authors: Schilowitz A. M. , Wiesenfeld J. R.
Published: February 2003

Photodissociation of KI at 193 nm in the presence of Xe yields excimer emission in the region 410–530 nm. The intensity distribution differs dramatically from that observed following direct pumping, K (5 2 P)←K (4 2 S), the green emission being significantly weaker than that reported previously. Also, the rate of K(5 2 P) deactivation upon collision with Xe is quite inefficient, k<10−13 cm3 molecule−1 s−1. A simple mechanism involving a curve crossing in KXe resulting in efficient quenching of K (5 2 P) to K(5 2 S) is not supported.
Spectroscopic detection of silylene in the infrared multiphoton decomposition of silane
Authors: O’Keefe J. F. , Lampe F. W.
Published: February 2003

Spectroscopic examination of the luminescence from SiH4 and SiH4-SiF4 mixtures that are irradiated with an unfocussed, pulsed CO2 infrared laser at a fluence of 0.75 J/cm2 shows the emission to be due to the transitions SiH2(1B1, ν′=2, 3) →SiH2(1A1, ν″=1) and thus clearly demonstrates the presence of SiH2 in the decomposing gas. The form of the time dependence of the emission is determined by the collisional energy pooling processes that produce highly excited SiH4 molecules and does not permit an assessment of the lifetime of the 1B1 state of SiH2.
Infrared absorption of thin metal films: Pt on Si
Authors: Mahan G. D. , Marple D. T. F.
Published: February 2003

It is shown that metal films will absorb more infrared radiation if they are made thinner. For most metals, the maximum absorptance is obtained for films which are less than 100 Å in thickness. Experiments are reported here for Pt on Si, for which peak absorptance of 3.39-μm radiation incident through the Si is found to be 0.5±0.1 for a film 80 Å thick.
Optically pumped sodium-dimer supersonic-beam laser
Authors: Jones P. L. , Gaubatz U. , Hefter U. , Bergmann K. , Wellegehausen B.
Published: February 2003

Continuous laser operation in an optically pumped Na2 supersonic beam with thresholds below 1 mW and output powers in the order of 600 μW have been achieved. Laser operation independent of molecular beam parameters is investigated. This novel device holds promise for the creation of molecular beams with highly vibrationally excited molecules.
Saturation splitting of phase-conjugate line through resonant degenerate four-wave mixing in SF6
Authors: Boulnois J. L. , Aubourg P. , Van Lerberghe A. , Agrawal Govind P.
Published: February 2003

Using the isolated P(33)A 12 one-photon resonance in SF6 the degenerate four-wave mixing spectrum is shown to exhibit line splitting below a critical pressure. The dependence of this saturation splitting on the gas pressure and the pump intensity is quantitatively studied.
Photoexcited carrier lifetime and Auger recombination in 1.3-μm InGaAsP
Authors: Sermage B. , Eichler H. J. , Heritage J. P. , Nelson R. J. , Dutta N. K.
Published: February 2003

We have measured the time-resolved decay of photoexcited carriers in InGaAsP subsequent to mode-locked laser pulse excitation at 1.06 μ. Carrier decay rates were evaluated from bleaching recovery and luminescence decay measurements as a function of injected carrier density over a two-decade range (1017–1019 cm−3). At low and moderate density the decay rate follows the variation with excitation expected for radiative decay. At high carrier density (above 2×1018 cm−3), the decay rate increases more rapidly with carrier density, indicating the onset of nonradiative recombination which can be accounted for by Auger recombination with an Auger coefficient of A=2.3±1×10−29 cm6 s−1. This compares to the calculated Auger coefficient range of 0.7–1.4×10−28 cm6 s−1. We discuss the influence of our measured decay rates on the threshold temperature dependence of InGaAsP-1.3 μ lasers by calculating expected T0 values, using a range of representative values for threshold carrier density and temperature dependence of the Auger decay rate. Our results suggest that while Auger recombination does contribute to the temperture dependence of the InGaAsP-1.3 μ laser it may not alone fully account for the observed room- temperature T0 values.
Plasma enhanced beam deposition of thin dielectric films
Authors: Chang R. P. H. , Darack S.
Published: February 2003

A low-temperature (30–250 °C) technique for depositing thin films of stoichiometric, amorphous dielectric layers with a sharp interface between the film and the substrate is proposed and demonstrated. The technique uses a combination of atomic or molecular beams of which at least one of the sources is generated by a plasma. As examples, SiO2 and Al2O3 films have been deposited on Si, GaAs, InP, InGaAs substrates. It is shown that the interface between the dielectric and the semiconductor is extremely sharp and that no native growth of oxides occurred on the semiconductor surface during film deposition. The physical properties of the deposited SiO2 are nearly identical to those of thermal oxides grown on Si. Preliminary electrical properties show that the films have a breakdown field strength of about 5×106 V/cm, and the 1-MHz C-V curves shown hystereses of 50 mV with a sweep rate of 100 mV/s. The fixed charge density is about 3.5×1011 cm−2.
Efficient visible photoluminescence in the binary a-Si:Hx alloy system
Authors: Wolford D. J. , Reimer J. A. , Scott B. A.
Published: February 2003

We report the photoluminescence (PL) and structural properties of a new class of efficient visible-light-emitting semiconductors: low defect density a-Si:Hx alloys. For films prepared by the (thermal) homogeneous chemical vapor deposition (HOMOCVD) method, new broadband PL develops for x>0.3, reaching a peak emission energy of 2.05 eV for a hydrogen content x=0.66 (40 at. % H). We attribute the wide gaps to the influence of Si–H bonding on the density of states near the valence band edge. We ascribe the new PL process to band-to-band recombination from within the alloy band tails. This emission persists at room temperature with an integrated intensity comparable to conventional light-emitting diode (LED) materials. Qualitatively similar results are obtained for low-temperature-deposited rf plasma films prepared from Si2H6, but not from SiH4. We show that a low Si dangling bond concentration is the key factor, for all the different film types, to achieving efficient luminescence.
Optically pumped ring laser oscillation to vibrational levels near dissociation and to the continuum in Na2
Authors: Bahns John T. , Verma K. K. , Rajaei-Rizi A. R. , Stwalley W. C.
Published: February 2003

Unidirectional laser oscillation of Na2 dimers has been observed using 5682-Å single-mode Kr+ laser pumping. This laser action involves not only bound-bound transitions, but also (for the first time) bound-free transitions between two strongly bound electronic states (the A 1Σ+u and X 1Σ+g states). Twelve bound-bound transitions and two regions of bound-free emission, in the region 7200–8300 Å, were observed. Previously reported laser-induced fluorescence results were used to assign both the bound-bound and bound-free transitions to the A 1Σ+u –X 1Σ+g band system of Na2. The bound-bound transitions are also of particular interest because they all occur to very highly excited vibrational levels within 10% of dissociation (laser oscillation to lower levels should also be possible but was not examined). The pressure for optimum intensity was found to be ∼0.65 Torr.
Measurement of picosecond ultraviolet laser pulsewidths using an electrical autocorrelator
Authors: Bokor J. , Bucksbaum P. H. , Auston D. H.
Published: February 2003

The use of an electrical autocorrelator constructed of two ultrafast photoconducting detectors as a general technique for the measurement of picosecond ultraviolet laser pulsewidths is demonstrated.
cw recombination laser action in a cadmium vapor arc
Authors: Silfvast W. T. , Wood O. R. , Macklin J. J.
Published: February 2003

Continuous-wave laser oscillation at 1.40, 1.43, 1.45, and 1.64 μm has been achieved in a recombining plasma produced by a Cd vapor arc in the presence of low-pressure rapidly flowing He gas. The variation of gain with distance from the arc, calculated using a simple recombination model, is in close agreement with experiment. The experimental techniques used in this work should be applicable to the development of cw lasers in other metal vapor arcs.
Plasma rotation measurements using spectral lines from charge-transfer reactions
Authors: Isler R. C. , Murray L. E.
Published: February 2003

The central toroidal rotation velocities of tokamak plasmas have been measured from the Doppler shifts of spectral lines that are excited by charge transfer of the neutral hydrogen heating beams with fully ionized oxygen.
Switchable coaxial optical coupler using a liquid crystal mixture
Authors: Busurin V. I. , Green M. , Cozens J. R. , Leaver K. D.
Published: February 2003

A novel coaxial form of optical coupler has been constructed in which 95% intensity modulation was achieved, using a liquid crystal mixture as the electro-optic medium. The behavior of this coupler with varying temperature and applied voltage has been elucidated by comparison with the behavior of the same coupler when the liquid crystal was replaced by a silicone oil whose refractive index could be reproducibly and controllably varied.
Origin of lamellae in radiatively melted silicon films
Authors: Hawkins W. G. , Biegelsen D. K.
Published: February 2003

Coexisting liquid and solid regions have been reported to occur in the melt zone of radiatively heated silicon thin films. We demonstrate here the mechanism of creation of these lamellae. The existence and characteristic size of the lamellae are shown to arise simply from the increased reflectivity of silicon on melting and the thermal properties of the sample.
Stereoscopic depth analysis by thermal wave transmission for nondestructive evaluation
Authors: Busse G. , Renk K. F.
Published: February 2003

Thermal wave transmission probing is used for nondestructive remote subsurface flaw detection in metal. It is shown that depth information of subsurface structure is obtained when two thermal wave sources are operated simultaneously in a stereoscopic arrangement.
Absence of the Gunn effect in p-In0.53Ga0.47As
Authors: Otsuka E.
Published: February 2003

The reported absence of the Gunn effect in photoexcited p-In0.53Ga0.47As is discussed from the viewpoint of the lesser electron scattering rate by acceptors than by donors. The donor-to-acceptor ratio of electron scattering cross sections is calculated for the carrier density range 1015–1020 cm−3. It is found that the electron-acceptor scattering cross section is by two orders of magnitude smaller than the electron-donor scattering cross section.
EL2 distributions in doped and undoped liquid encapsulated Czochralski GaAs
Authors: Holmes D. E. , Chen R. T. , Yang J.
Published: February 2003

We compare the longitudinal and radial distributions of EL2 in undoped semi-insulating and intentionally doped n-type GaAs crystals grown by the liquid encapsulated Czochralski technique. Longitudinal profiles in undoped crystals are controlled by changes in melt stoichiometry as the crystal is pulled from the melt. EL2 profiles along crystals doped above about 1×1017 cm−3, on the other hand, are controlled primarily by the carrier concentration as a result of the suppression of EL2 by free electrons. Radial EL2 profiles are typically W shaped and M shaped in undoped and doped (above threshold) crystals, respectively. The origin of these radial profiles is discussed in terms of residual stress, melt stoichiometry, and the suppression of EL2 by electrons. Our results are also discussed in the light of the antisite model for EL2.
InGaAsP/InP undercut mesa laser with planar polyimide passivation
Authors: Koren U. , Chen T. R. , Harder C. , Hasson A. , Yu K. L. , Chiu L. C. , Margalit S. , Yariv A.
Published: February 2003

An undercut mesa laser is fabricated on an n+-InP substrate using a single step liquid phase epitaxy growth process and a planar structure is obtained by using a polyimide filling layer. The lasers operate at fundamental transverse mode due to a scattering loss mechanism. Threshold currents of 18 mA and stable single transverse mode operating at high currents are obtained.
Single longitudinal-mode optical phonon scattering in Ga0.47In0.53As
Authors: Pearsall T. P. , Carles R. , Portal J. C.
Published: February 2003

We show that only one of the four Raman active modes in Ga0.47In0.53As shows the required symmetry behavior for longitudinal optical (LO) phonons. An additional mode previously supposed to be LO shows mixed-mode behavior and may be disorder activated. Our results prove that only one phonon mode in Ga0.47In0.53As is active in scattering electronic carriers, and thus in determining both electron and hole mobilities.
Computer simulation of carrier transport in planar doped barrier diodes
Authors: Cook Robert K.
Published: February 2003

The operation of planar doped barrier diodes is studied using a numerical device simulation which solves the carrier energy transport equation self-consistently with the current continuity equation and Poisson’s equation. This allows the effects of space-charge injection and carrier heating, which have been neglected in previous studies of these devices, to be studied quantitatively. Results for two different doping profiles are presented and compared with the results calculated using the conventional quasi-equilibrium transport model. Significant differences between the results are found, demonstrating the importance of including hot-carrier effects in modeling these devices.
Melt dynamics of silicon-on-sapphire during pulsed laser annealing
Authors: Thompson Michael O. , Galvin G. J. , Mayer J. W. , Peercy P. S. , Hammond R. B.
Published: February 2003

Transient electrical conductance measurements have been made on 0.45-μm silicon-on-sapphire during pulsed laser annealing with 25-ns ruby irradiation. The photoconductive contribution to the transient current was sufficiently small that the entire melt and resolidification process could be directly observed. The technique yields quantitative measures of melt depths, melting velocities (5–13 m/s), and solidification velocities (2.8–3.3 m/s). Combined with the complementary techniques of time-resolved reflectivity, energy transmission, and calorimetric energy absorption, transient conductance provides a powerful new diagnostic for investigating melt dynamics.
Observation of oxidation-enhanced and oxidation-retarded diffusion of antimony in silicon
Authors: Tan T. Y. , Ginsberg B. J.
Published: February 2003

An experiment was carried out to study oxidation-enhanced and oxidation-retarded diffusion (OED and ORD) of Sb in (100) and (111) Si wafers oxidized in dry O2 at 1160 °C. The ORD data of (100) wafers agree well with those of Mizuo and Higuchi and with the prediction of a model assuming that Si self-interstitials and vacancies coexist in Si in thermal equilibrium at high temperatures. A small adjustment to the interstitial supersaturation values is needed to bring the ORD/OED data of (111) wafers to fit with the model satisfactorily. This indicates the existence of a mechanism which injects vacancies into (111) wafers in addition to the normal mechanism of interstitial injection due to SiO2 growth.
Submicrometer periodicity gratings as artificial anisotropic dielectrics
Authors: Flanders Dale C.
Published: February 2003

Gratings of dielectric material can act as homogeneous birefringent materials if the wavelength of the incident radiation is greater than twice the period of the grating. For the case of square profile gratings, simple equations predict the birefringence versus linewidth-to-period ratio of the gratings. By using x-ray lithography and reactive ion etching, 240-nm period gratings of polymethylmethacrylate and silicon nitride were fabricated with various linewidths. The birefringence of these was measured at 632.8 nm and found to agree closely with the theory. Silicon nitride gratings which act as half-wave and quarter-wave plates in the visible were made.
Microprobe Raman analysis of picosecond laser annealed implanted silicon
Authors: Nissim Y. I. , Sapriel J. , Oudar J. L.
Published: February 2003

The phase transformation induced by a picosecond laser pulse in implanted amorphized silicon has been studied. A single 30-ps pulse at 1.06- and 0.532-μm wavelengths from a mode-locked neodymium:yttrium aluminum garnet laser was used to generate a multiannular (up to five rings) recrystallization pattern on an implanted silicon substrate. A Raman microprobe with a 1-μm spatial resolution was utilized to investigate the annealed spots. These measurements combined with polarized light scattering experiments resulted in a detailed spatial analysis (parallel and perpendicular to the surface) of the recrystallization pattern, that was related to the picosecond laser energy and wavelength. At high incident energies single crystal silicon is observed in the central spot and in the first recrystallized ring of the annealed area.
Auger recombination in InGaAsP
Authors: Haug A.
Published: February 2003

Auger recombination in InGaAsP is calculated taking into account a realistic band structure instead of the usual parabolic approximation. It follows that the direct conduction-band process is negligible (at T=300 K), contrary to the parabolic approximation. Actually the valence-band process prevails by far as long as only direct Auger processes are considered. However, if phonon-assisted Auger recombination is included the phonon-assisted conduction-band process dominates. Altogether, a decrease of Auger recombination results, which is in agreement with experiments.
Electron traps in GaAs1−xPx alloys
Authors: Calleja E. , Muñoz E. , Garcia F.
Published: February 2003

Deep level electron traps in vapor phase epitaxial GaAs1−xPx materials have been studied by transient capacitance spectroscopy. Light-emitting diodes and Schottky barriers with x=0, 0.3, 0.4, 0.65, 0.85, and x=1 have been used. Two traps with emission activation energies of ΔEe =0.16±0.02 eV and 0.27±0.02 eV have been found for all samples with x>0.3. A third level with ΔEe =0.87 eV is present in samples with x=0.3 and occasionally in diodes with x=0.4.
Indium diffusion in cadmium selenide thin-film transistors with indium-gold contacts
Authors: Scilla G. J. , Luo F. C.
Published: February 2003

The thicknesses of the In layer in the composite In-Au source-drain contacts for CdSe thin-film transistors (TFT’s) are found to have significant effects on the performance of the devices. By varying the In thickness from 70 to 180 Å, the TFT’s have been changed from strong enhancement to depletion. This effect can be explained by the lateral diffusion of In into CdSe. Using secondary ion mass spectrometry (SIMS), In has been detected in the CdSe. Annealing the devices in N2 at 375 °C increases the concentration of In in CdSe by a factor of 3.
Optoelectronic enhancement of the Sagnac effect in a ring resonator and related effect of directional bistability
Authors: Kaplan A. E.
Published: February 2003

A substantial enhancement (by orders of magnitude) of the Sagnac effect in a passive ring resonator can be attained by using a nonreciprocal feedback. This feedback is based on the nonreciprocal element controlled by the signal proportional to the difference between intensities of counterpropagating waves, and is an optoelectronic analog of nonlinear nonreciprocity proposed by us earlier. Under some critical conditions, this system can exhibit directional bistability and directional switching of the counterpropagating waves.
First order optoelectronic correlation utilizing metal-semiconductor-metal photodetectors
Authors: Yamada Syoji , Urisu Tsuneo , Sugeta Takayuki , Mizushima Yoshihiko
Published: February 2003

Optoelectronic correlations between two n-GaAs metal-semiconductor-metal photodetectors were measured. An arrangement of two photosensing areas, each having a separation of far less than the minimum possible wavelength on the stripline, was examined. The equivalent circuit analysis clearly explained the observed correlation signals and revealed the limits of the photodetector response.
Ion mixing to produce amorphous Mo-Ru superconducting films
Authors: Liu B. X. , Clemens B. M. , Gaboriaud R. , Johnson W. L. , Nicolet M-A.
Published: February 2003

Amorphous Mo55Ru45 alloy films were formed by ion mixing of multilayered samples. The ion mixed films, which contain no metalloid element, show excellent superconducting properties. The measured properties are correlated with the microstructure obtained by both x-ray diffraction and transmission electron microscopy.
Picosecond trapping of photocarriers in amorphous silicon
Authors: Vardeny Z. , Strait J. , Tauc J.
Published: February 2003

Trapping of photoexcited carriers in the picosecond and subnanosecond time domains was studied by measuring the decay of photoinduced absorption (PA) in a-Si, a-Si:F, a-Si:H, and a-Si:H:F. We found that when the midgap density of states decreases, both the trapping time and its temperature dependence increase. The observed PA decays are compared to the picosecond photoconductivity decays, and the differences in the response curves are explained. The possibility that geminate recombination might explain our results is ruled out.
Chemically induced interface states in photoelectrochemical cells
Authors: Butler M. A. , Ginley D. S.
Published: February 2003

This letter reports for the first time a significant improvement of p-GaP photocathodes for hydrogen evolution by treatment with ruthenium ions. Sub-band-gap spectroscopy has revealed that contrary to expectations the ruthenium treatment introduces new states in the gap 1.23 eV above the valence-band edge and close to a band edge. A new model based upon kinetic considerations is proposed to explain these effects.
Electrical and optical properties of sputtered amorphous silicon films prepared under a reduced pumping speed
Authors: Van Dong Nguyen , Fournier Y. , Le Ny J. Y.
Published: February 2003

A series of amorphous silicon (a-Si) films have been deposited by dc sputtering. We have found a new preparation parameter, namely, the pumping speed of the secondary vacuum pump which has a considerable influence on the electronic properties of the material. Samples deposited under a reduced pumping speed possess electrical properties which are extremely sensitive to the presence of hydrogen. Conductivity and photoconductivity may increase over several orders of magnitude with the addition of a relatively small amount of hydrogen.
Defect states in electron irradiated InGaAsP
Authors: Levinson M. , Temkin H.
Published: February 2003

Capacitance transient spectroscopy has been used to study defect states in 1-MeV electron irradiated liquid phase epitaxial InGaAsP. No states were found in the unirradiated material. Irradiation resulted in one electron trap with an electron emission activation energy of 0.38 eV and two hole traps with hole emission activations of 0.29 and 0.46 eV. Annealing behavior and the broad shape of the deep level transient spectroscopy peaks suggest that defect properties are affected by local ordering and stoichiometry in the material. All three defects recover significantly at temperatures <200 °C.
Defects in electron-irradiated, gallium-doped silicon
Authors: DeAngelis Henry M. , Drevinsky Peter J.
Published: February 2003

Defect processes were studied in electron-irradiated, Ga-doped silicon using deep level transient spectroscopy. Evidence for the production of a Ga-related defect state is presented. Changes in minority-carrier lifetime are correlated with recovery and growth of defect states in annealing studies of Ga-doped silicon.
Hydrogen passivation of defects in silicon ribbon grown by the edge-defined film-fed growth process
Authors: Hanoka J. I. , Seager C. H. , Sharp D. J. , Panitz J. K. G.
Published: February 2003

Electrically active defects in edge-defined film-fed grown silicon ribbon solar cells have been passivated using a hydrogen plasma from a Kaufman ion source. Significant improvements in solar cell efficiency for both low diffusion length starting material (∼20 μm) and high diffusion length (∼50 μm) material have been obtained. For the former, passivation has produced solar cell efficiency improvements as high as 41% and in the case of the latter, solar cell efficiencies as high as 14.5% (AM1) have been obtained. Electron beam induced current micrographs are shown which indicate near total defect passivation for at least the top 9 μm of the solar cell.
Superconducting properties of a liquid-infiltration Nb-Nb3Sn composite formed during a low-temperature reaction
Authors: Hong M. , Hull G. W. , Holthuis J. T. , Hassenzahl W. V. , Hong J. M.
Published: February 2003

A powder metallurgy based ‘‘liquid-infiltration’’ method was used to produce multifilamentary Nb-Sn composite wires. New heat treatments combining relatively low-temperature aging (≤800 °C) and long reaction time (≥ one day) were used to form superconducting A15 Nb3Sn. This heat treatment can be used for large conductors and practical magnets. Transmission electron microscopy studies revealed that the A15 Nb3Sn was formed in fine filaments which were embedded in the ductile Nb matrix. Small, equiaxed A15 grains extended across the reacted filament. A Tc onset of 17.9 K with a 0.4-K transition width was obtained. Excellent high-field critical currents, overall Jc’s ≥104 A/cm2 in a field of 18 T at 4.2 K, were achieved.
Photodeposition of Ti and application to direct writing of Ti:LiNbO3 waveguides
Authors: Tsao J. Y. , Becker R. A. , Ehrlich D. J. , Leonberger F. J.
Published: February 2003

An ultraviolet laser photodeposition process based on the photolysis of TiCl4 has been developed. The photochemistry of this new metal-halide system has been shown to involve a surface-catalyzed reaction confined to adsorbed molecular layers. By using this process, Ti films have been deposited on LiNbO3 to form, after diffusion, 4-μm-wide single-mode channel waveguides of comparable quality to conventionally fabricated Ti-indiffused guides. The technique introduces new design flexibility into waveguide fabrication, permitting controlled gradations in the diffused index change and the lateral width along the guide.
Laser-formed connections using polyimide
Authors: Raffel J. I. , Freidin J. F. , Chapman G. H.
Published: February 2003

Electrical connections have been formed in a new lateral link structure which uses polyimide in the gap between, and overlapping, two aluminum electrodes. An argon ion laser, with a pulse width of 1 ms and power levels of about 2 W, was used to locally graphitize the polyimide. One kilohm connections were formed reliably in links ranging in width between 4 and 15 μm and gap length between 2 and 5 μm. This technique is the simplest yet proposed for restructuring the connections on an integrated circuit, after fabrication and test, in order to incorporate redundancy for yield improvement.
Photovoltaically active p layers of amorphous silicon
Authors: Faughnan B. W. , Hanak J. J.
Published: February 2003

Studies on amorphous silicon p-n diodes have shown that the p layers are photovoltaically active. Jsc of up to 3.4 mA/cm2 and Voc of 780 mV have been observed. Detailed quantum efficiency measurements were performed as a function of bias voltage, p-layer thickness, and boron doping. The data fit a simple depletion width model in which all photogenerated carriers created inside the depletion region are collected. An additional ‘‘reverse’’ barrier depletion width is assumed at the interface between the front transparent oxide electrode and the p layer to explain the results. A 10-nm-thick p layer typically used in p-i-n cells could collect up to 1 mA/cm2 if the electric field in the p layer is greater than 105 V/cm.