bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of far-infrared and mid-infrared laser transitions in the NH3 laser
Authors: Nelson L. Y. , Buchwald M. I. , Jones C. R.
Published: February 2003

Laser emission on the conventional 12.8-μm NH3 laser transition, optically pumped by the CO2 9R16 line, can be completely quenched and replaced by emission at 12.2μm. Cascading far-infrared laser transitions in the excited ammonia ν2 state are shown to be responsible for the shift in wavelength.
Self-sustained pulsations and negative-resistance behavior in InGaAsP (λ=1.3 μm) double-heterostructure lasers
Authors: Nelson R. J. , Dutta N. K.
Published: February 2003

Self-sustained pulsations, superlinear emission, and negative-resistance behavior are reported for InGaAsP (λ=1.3 μm) double-heterostructure lasers. For nitride-stripe devices the incidence rate for pulsations is approximately 40%. Nearly 50% of these pulsating devices exhibit a light output with a large differential quantum efficiency over a small current range. These light jumps are associated with a negative-resistance behavior, as observed in the electrical derivative I dV/dI, and with pulsations. Studies of buried-waveguide devices show a much lower incidence rate of pulsations in these refractive-index-guided structures. Superlinear emission and negative-resistance behavior have not been observed in these buried-waveguide lasers.
Resonant enhancement of impact in Ga1−xAlxSb
Authors: Hildebrand O. , Kuebart W. , Pilkuhn M. H.
Published: February 2003

Impact ionization coefficients α and β of Ga1−xAlxSb avalanche photodiodes were measured for 0⩽x<0.3. The hole ionization coefficient β shows a strong band-structure effect: a resonant enhancement at x=0.065 (300 K) due to initiation of the ionization process by holes from the spin-orbit splitoff valence band. β/α can exceed values of 20 when the spin-orbit splitting Δ is equal to the band-gap energy Eg (resonant condition). The hole ionization coefficient depends exponentially on the difference between energy and band-gap energy Ei−Eg.
A channeling study of Sb trapping in Fe-Ti-C-Sb alloys
Authors: Knapp J. A. , Follstaedt D. M.
Published: February 2003

The trapping site for Sb in an Fe crystal containing TiC precipitates has been determined using channeling techniques in ion backscattering and ion-induced characteristic x-ray analyses of ion-implanted alloys. From the orientation of the TiC particles relative to the Fe host lattice, we show that ≳60% of the trapped Sb atoms occupy Fe sites at the Fe-TiC interface, rather than Ti sites within the TiC particles.
Determination of the three-dimensional lattice mismatch in quaternary III-V liquid phase epitaxial layers using simultaneous Bragg diffraction of x-rays
Authors: Chang Shih-Lin
Published: February 2003

Because multiple simultaneous reflection of x rays is very sensitive to lattice deformation, the six-beam, (000) (006) (22̄4) (22̄2) (2̄24) (2̄22) multiple reflection was used to record simultaneously the information about the lattice mismatch of [001] InGaAsP materials using a divergent x-ray source. The lattice mismatches in directions parallel and perpendicular to [001], determined from a single divergent-beam photograph, increase as the As concentration in liquid composition XlAs increases. The procedure was used without difficulty for XlGa as low as 0.0007 and XlAs in the range 0.006–0.01.
Oxidation mechanisms in TiSi2 films on single silicon substrates
Authors: Chen Jiann-Ruey , Houng Mau-Phon , Hsiung Shen-Kan , Liu Yuen-chung
Published: February 2003

Ti is deposited on single silicon wafer and then forms TiSi2 by thermal annealing in vacuum. In the steam oxidation, TiSi2 first dissociates and forms a Ti compound and SiO2. After the formation of Ti compound reaches the saturation level, the substrate Si rapidly diffuses through the TiSi2 to form SiO2, while the TiSi2 remains inert. A two-step oxidation process is thus described. The calculated activation energy of reaction is 46.2 kcal/mol, and that of diffusion is 32 kcal/mol.
Stimulated Raman scattering from 20-Å layers of silicon on sapphire
Authors: Levine B. F. , Bethea C. G. , Tretola A. R. , Korngor M.
Published: February 2003

We have developed a novel triply modulated stimulated Raman gain spectrometer which reduces unwanted background effects by over 105. This has allowed the high resolution (Δν=1 cm−1) measurement of 20 Å of Si on sapphire with a signal-to-noise ratio of 100, with only 2 min of data collection. This sensitivity is several orders of magnitude larger than spontaneous Raman scattering.
Picosecond optical sampling technique for measuring the speed of fast electro-optic switch/modulators
Authors: Alferness R. C. , Economou N. P. , Buhl L. L.
Published: February 2003

We propose and demonstrate a new technique for measuring the pulse response of fast electro-optic switch/modulators. Using synchronized trains of electrical drive pulses and picosecond optical sampling pulses, switching times as short as ∼50 psec can be measured without requiring a fast photodiode.
Raman spectra from heat-treated semi-insulating GaAs
Authors: Nakamura Tomoji , Ushirokawa Akio , Katoda Takashi
Published: February 2003

Raman-spectra measurements were made on semi-insulating (SI) GaAs heat-treated in an atmosphere of H2 or Ar to study the effect of structural changes or strains on a thermal conversion of Si GaAs. Correlations between Raman spectra and electrical changes of SI GaAs indicate that strains in the interface region between SI GaAs and a dielectric film is, at least, one of the origins of the thermal conversion, while the structural changes accompanying the generation of the TO-phonon line has no effect on the thermal conversion.
Consequences of Pierce instability for focusing of neutralized ion beams
Authors: Poukey J. W. , Quintenz J. P. , Olson C. L.
Published: February 2003

The effects of Pierce-type space-charge instabilities in high-energy ion beams, initially neutralized by co-moving electrons, are discussed in terms of planar and two-dimensional spherical geometries. The limiting ion current which can reach a target is given.
Optically induced bistable states in metal/tunnel-oxide/semiconductor (MTOS) junctions
Authors: Lai S. K. , Dressendorfer P. V. , Ma T. P. , Barker R. C.
Published: February 2003

A new switching phenomenon in metal-oxide semiconductor tunnel junction has been discovered. With a sufficiently large negative bias applied to the electrode, incident visible light of intensity greater than about 1 μW/cm2 causes the reverse-biased junction to switch from a low-current to a high-current state. It is believed that hot-electron-induced impact ionization provides the positive feedback necessary for switching, and causes the junction to remain in its high current-state after the optical exciation is removed. The junction may be switched back to the low-current state electrically. The basic junction characteristics have been measured, and a simple model for the switching phenomenon has been developed.
Orientation and velocity dependence of solute trapping in Si
Authors: Baeri P. , Foti G. , Poate J. M. , Campisano S. U. , Cullis A. G.
Published: February 2003

Interface segregation coefficients have been measured for Bi in Si for melt growth as a function of velocity for (111) and (100) crystals. Surface layers were melted by ruby laser irradiation and liquid-solid interface velocities varied from 0.8 to 5 m/s by changing Si substrate temperatures or laser pulse length. Segregation coefficients are strongly dependent on velocity and orientation in this range.
Calorimetric absorption spectroscopy of nonradiative recombination processes in GaP
Authors: Bimberg D. , Bubenzer A.
Published: February 2003

A new, simple and highly sensitive spectroscopic method, calorimetric absorption spectroscopy (CAS), for direct detection of phonons emitted via nonradiative recombination processes of charge carriers bound to defects or impurities in solids is demonstrated. Electronic levels of these centers are populated by resonant excitation with monochromatic light. The phonons emitted during recombination are detected with a low-temperature calorimeter with a sensitivity of ≊10−12 J. Thus absorption coefficients as low as ≊10−7 cm−1 and quantum efficiencies can be determined without using radiation detectors. CAS spectra of N-  and S-doped GaP are presented, and the low-temperature internal quantum efficiency of the nitrogen bound exciton is found to be close to 100%.
Self-annealing of ion-implanted silicon: First experimental results
Authors: Cembali G. F. , Merli P. G. , Zignani F.
Published: February 2003

The first use of an ion beam to dope a silicon specimen by implantation and to anneal it in a single operation is reported. Experimental conditions as well as electrical and structural characterizations of self-annealed specimens are presented.
Charge injection over triangular barriers in unipolar semiconductor structures
Authors: Kazarinov R. F. , Luryi S.
Published: February 2003

A theory of unipolar current over triangular barriers in semiconductor structures is developed. Diodes based on such barriers have been recently fabricated by molecular beam epitaxy using either variable-gap or modulation-doped semiconductors. In these diodes the current is due to unipolar injection of electrons. Exact analytic expression for current-voltage characteristics is obtained. Comparison is made with recent experimental data.
A low-temperature fabrication process of polycrystalline silicon-silicon p+-n junction diode
Authors: Wu Chii-ming M. , Yang Edward S.
Published: February 2003

A new method has been developed to form a p+-n polycrystalline-crystalline junction at low temperature. The technique involves the use of an e-beam evaporated polycrystalline silicon-aluminum-polycrystalline silicon multilayer structure to obtain an Al-rich polycrystalline film by heat treatment at 600 °C. Experimenal evidence indicates that the current conduction is dominated by electron recombination at the interface between the polycrystalline silicon and the substrate. The best fit between a simple model and expeirmental data yields an effective recombination velocity of 5×104 cm/sec, a value consistent with carrier recombination at the grain boundaries of polycrystalline silicon.
Optical bistability using a magneto-optic modulator
Authors: Umegaki Shinsuke , Inoue Hiroaki , Yoshino Toshihiko
Published: February 2003

Optical bistability is realized using a Faraday rotator which has a high rotating power owing to multiple reflections in a planar glass plate. The linearly polarized light is modulated by the coil current of the electromagnet. Optical hysteresis is observed when the current is changed in proportion to the intensity of the light transmitted through the modulator. An application of this device to stabilizing the light intensity of the cw laser intensity is described.
Experimental observation of anomalous electromagnetic absorption in thin-layered media
Authors: Amittay A. , Einziger P.D. , Tamir T.
Published: February 2003

The anomalous high absorption predicted to occur for an optical beam incident on a thin multilayered configuration having only slight intrinsic losses has been verified by means of a microwave model. This observation is consistent with a leaky-wave interpretation for the reflection properties of the absorbing layered structure.
Spatial resolution of an intracavity image upconverter
Authors: Schow F. L. , Riazi A. , Gandhi O. P. , Grow R. W.
Published: February 2003

An intracavity image upconversion system, using a proustite crystal and a flashlamp-pumped dye laser, is described. Experimental results regarding the spatial resolution of the system are also presented, and the conversion efficiency is discussed.
Channel electron conduction in laser-annealed polycrystalline silicon metal-oxide semiconductor field-effect transistors
Authors: Lee Han-Sheng
Published: February 2003

A scanned cw Ar+ laser was used to anneal the polycrystalline silicon on nitride structures. Laser power varied from l0 to 15 W in increments of 1 W, the beam diameter was ∼40 μm and the scan rate was ∼12.5 cm/s. The measured field-effect electron mobility of the metal-oxide semiconductor field effect transistor fabricated on the annealed silicon increases with increasing laser power. In transistors annealed at power ⩽11 W, an intercrystalline potential barrier resulting from the electron trapping at crystallite and grain boundary regions was found to be the dominant factor in the channel electron conduction. In transistors annealed at power ⩾ 12 W, channel conduction is limited by scattering from surface structure imperfections.
Low-order TE0q operation of a CO2 laser for transmission through circular metallic waveguides
Authors: Marhic M. E. , Garmire E.
Published: February 2003

We report the separate TE01 and TE02 operation of a CO2 laser in a hybrid oscillator formed by placing a circular metallic waveguide and a focusing lens inside the cavity of an otherwise conventional laser. With the TE01 output focused into a passive waveguide outside the cavity, transmission in excess of 90% has been measured through a 31-cm-long, 0.5-mm-i.d. straight metallic tube. Bending increased the losses far more than originally anticipated.
Absolute two-photo fluorescence with low-power cw lasers
Authors: Catalano Ida M. , Cingolani Aldo
Published: February 2003

A method for absolute two-photon cross-section-value γ2 evaluation by means of one- and two-photon fluorescence comparative measurements and using a low-power, single-mode cw laser is presented. This method is applied to a rhodamine B solution. The experimental value γ2 we obtained is compared with previous experimental data measured by a high-power laser source.
Interferometric measurements with laser FM sidebands
Authors: Bjorklund G. C. , Jain K. , Hope J. D.
Published: February 2003

Hysteresis in piezoelectric transducers down to 20 Å and gas pressure changes as small as 10 mTorr are measured by locking a laser FM sideband to an interferometer resonance. In addition, rapid monitoring of large excursion motions with 200-Å accuracy is achieved using an ’’optical frequency comb’’ consisting of multiple FM sidebands.
Mesa waveguide GaAs/GaAlAs injection laser grown by metalorganic chemical vapor deposition
Authors: Scifres D. R. , Burnham R. D. , Streifer W.
Published: February 2003

An easily fabricated semiconductor laser, utilizing a mesa waveguide structure with a lenslike tapered active region for control of the optical laser mode, has been grown by metalorganic-chemical vapor deposition. This index-guided laser, which has thresholds of 40–60 mA and high differential quantum efficiency (∼40–50%), operates in the fundamental transverse mode up to its catastrophic damage limit. Single longitudinal mode is also obtained to greater than twice threshold.
Sequence of phase formation in planar metal-Si reaction couples
Authors: Tsaur B. Y. , Lau S. S. , Mayer J. W. , Nicolet M.-A.
Published: February 2003

A correlation is found between the sequence of phase formation in thin-film metal-Si interactions and the bulk equilibrium phase diagram. After formation of the first silicide phase, which generally follows the rule proposed by Walser and Bené, the next phase formed at the interface between the first phase and the remaining element (Si or metal) is the nearest congruently melting compound richer in the unreacted element. If the compounds between the first phase and the remaining element are all noncongruently melting compounds (such as peritectic or peritectoid phases), the next phase formed is that with the smallest temperature difference between the liquidus curve and the peritectic (or peritectoid) point.
Thin-film polycrystalline Cu2S/Cd1−xZnx S solar cells of 10% efficiency
Authors: Hall R. B. , Birkmire R. W. , Phillips J. E. , Meakin J. D.
Published: February 2003

Polycrytalline, thin-film Cu2S/Cd1−xZnxS heterojunction solar cells with conversion efficiencies of 10% have been prepared on Cd1−xZnxS with 0.1⩽x⩽0.2. Light-generated currents of up to 26 mA/cm2 (prorated to 100 mW/cm2) have been achieved, comparable to the best observed in Cu2S/CdS cells of the same design. The improved performance for Cu2S-based devices is as a consequence of the higher open-circuit voltage achieved with the addition of zinc.
Magnetic domain wall waves, parametrically excited in a stripe domain lattice in a garnet film
Authors: Spreen J. H. , Argyle B. E
Published: February 2003

Waves of magnetic domain wall motion in an array of straight, aligned stripe domains have been detected by observations of optical diffraction from the array. When the array is excited by a spatially uniform rf drive field of amplitude greater than 0.25 Oe peak, at a frequency near the resonant frequency of the uniform ’’breathing’’ mode of the array, dynamic spots appear in the diffraction pattern. The dynamic spot positions correspond to wave vectors oblique to the stripes, while the rf intensity variation suggests that the waves are parametrically excited at one-half the frequency of the spatially uniform mode.
Efficiency losses from carrier-type inhomogeneity in tungsten diselenide photoelectrodes
Authors: Menezes S. , Schneemeyer L. F. , Lewerenz H. J.
Published: February 2003

The coexistence of macroscopic p- and n-type domains in nominally smooth, single-crystal tungsten diselenide photoelectrodes leads to substantial efficiency losses in these crystals. The presence of such regions is demonstrated by rotating-disk electrode experiments, Seebeck coefficient measurements, and in situ topographic photogenerated carrier-collection analysis with a scanning laser spot. These results indicate the importance of controlling growth parameters to yield homogeneously doped crystals to achieve maximum solar conversion efficiencies.
A unidirectional, pulsed far-infrared ring laser
Authors: Peebles W. A. , Umstadter D. , Brower D. L. , Luhmann N. C.
Published: February 2003

The first study of a pulsed, far-infrared, ring laser is described. Unidirectional, traveling-wave operation is observed, thereby eliminating the spatial hole burning effects present in linear cavities. Single-mode output powers of 100 kW have been obtained.
Rayleigh wave reflection at plate edges
Authors: Portz K. , Stegeman G. I. , Maradudin A. A.
Published: February 2003

Plate mode expansions are used to evaluate the reflection, transmission, and bulk conversion of Rayleigh waves incident on the end of an isotropic plate of variable thickness.
Annealing ambient: A useful probe for interface interactions in thin films
Authors: Chang Chin-An
Published: February 2003

The annealing ambient in thin-film diffusion studies is shown to be a useful probe for the interface interactions in thin films. The earlier proposed surface potential model for the ambient effects has been successful in correlating the known ambient effects and predicting new ones for many systems. Based on the concepts of this model, a catalytic mechanism is proposed in which the ambient species can accelerate or hinder the initial mixing process at the interfaces, thereby affecting all the diffusion and reactions that follow. An example is shown where the interdiffusion in the Au/Cr films in an air ambient can be completely suppressed by CO.
Assessment by i
n s
i
t
u ellipsometry of composition profiles of Ga1−xAlxAs-GaAs heterostructures x
Authors: Hottier F. , Laurence G.
Published: February 2003

Quantitive assessment of the composition profiles of Ga1-xA1xAs-GaAs heterostructures, which usually relies on Auger or secondary-ion mass spectroscopy profiling techniques, can be gained by numerical analysis of in situ ellipsometry measurements. An inversion procedure that allows the computation of the refractive index profile from the ellipsometric angles measured during growth has been developed and applied to the assessment of a GaAs→ Ga1-xA1xAs-GaAs transition obtained in a metalorganic vapor phase epitaxy reactor.
The Schottky-barrier height of the contacts between some rare-earth metals (and silicides) and p-type silicon
Authors: Norde H. , de Sousa Pires J. , d’Heurle F. , Pesavento F. , Petersson S. , Tove P. A.
Published: February 2003

Some rare-earth elements, Tb, Er, Yb (including Y) and some of their respective silicides were found to make ohmic contacts to n-type silicon. Forward I/V and photoresponse measurements give values of about 0.7 eV for the Schottky-barrier height to p-type silicon. The sum of this value and of the experimentally estimated barrier height to n-type silicon, 0.4 eV, corresponds to the band gap of silicon.
Heterogeneous distribution of interstitial oxygen in annealed Czochralski-grown silicon crystals
Authors: Shimura Fumio , Ohnishi Yoshitake , Tsuya Hideki
Published: February 2003

It is shown that interstitial oxygen infrared (IR) absorption at 515 cm−1 decreases anomalously compared with the absorption at 1106 cm−1 in heat-treated Czochralski-grown silicon wafers. This phenomenon is described by the close correlation between the absorption coefficient ratio αr (α1106/α515), the half-bandwidth of the 1106-cm−1 peak, and the precipitated oxygen content during heat treatments. As a result, it is suggested that on the basis of IR absorption spectrum data interstitital oxygen atoms distribute heterogeneously in a silicon matrix as the forestage of Si-0 complex precipitation.
Microsecond time-scale Si regrowth using a line-source electron beam
Authors: Knapp J. A. , Picraux S. T.
Published: February 2003

A line-source electron beam annealing system has been used to regrow ion-implanted amorphous layers on (100) Si within dwell times of 150–600 μs. The results indicate solid-phase epitaxial regrowth at interface velocities as high as ∼3×107 Å/s. This solid-phase regrowth leads to minimum diffusion, in contrast to pulsed annealing in the liquid phase. The regrowth crystalline quality as measured by backscattering/channeling is nearly as good as for virgin Si. Line-source annealing can lead to reductions in processing times by factors of 104–106, compared to present cw spot annealing. The observed regrowth is shown to agree closely with calculation when oven regrowth data are extrapolated to temperatures near the melting point of crystalline Si. Our results indicate no large reduction of the melting point for amorphous Si, in constrast to a recent report.
Bistable optical switch using a yttrium-iron-garnet crystal with phase matching films
Authors: Shirasaki M. , Tagaki N. , Obokata T.
Published: February 2003

A magneto-optical switch using a yttrium-iron-garnet crystal plate with phase matching films requiring a drive voltage of only 5V is demonstrated at 1.3 μm wavelength. Using a semihard magnetic material, we developed a bistable magneto-optical switch which drives with a switching speed of 20 μs. An extinction ratio of 24 dB was obtained.
The influence of thermal point defects on the precipitation of oxygen in dislocation-free silicon crystals
Authors: de Kock A. J. R. , van de Wijgert W. M.
Published: February 2003

The precipitation of oxygen in regularly grown and in situ-quenched dislocation-free Czochralski silicon crystals has been investigated by means of infrared absorption spectroscopy, preferential etching, and x-ray transmission topography. In addition, the effect of doping with acceptor or donor impurities on oxygen precipitation has been studied. The experimental results indicate that at oxygen supersaturation ratios smaller than 20 the formation of nuclei for precipitation predominantly occurs via a heterogeneous in which thermal point defects, in particular silicon interstitials, play an important role.
Device-quality epitaxial AlAs by metalorganic-chemical vapor deposition
Authors: Coleman J. J. , Dapkus P. D. , Holonyak N. , Laidig W. D.
Published: February 2003

The growth and characterization of high-quality AlAs expitaxial layers on GaAs subtrates by metalorganic-chemical vapor deposition are described. The epitaxial layers described here are grown at intermediate temperatures (750 °C) and require no unusual reactor modifications. Comparison is made between single thick epitaxial layers and an 80-layer quantum-well heterostructure. Low-threshold photopumped laser data are presented, which indicate that the presence of AlAs in the active region of a laser (containing 80 AlAs-GaAs interfaces) does not interfere with cw room-temperature operation.
Grain boundaries in p-n junction diodes fabricated in laser-recrystallized silicon thin films
Authors: Johnson N. M. , Biegelsen D. K. , Moyer M. D.
Published: February 2003

Grain boundaries intersecting metallurgical p-n junctions have been evaluated in laser-recrystallized silicon thin films. Lateral p-n junction diodes were fabricated in islands of polycrystalline silicon which were defined on an amorphous substrate and cw laser recrystallized. The oxide-passivated diodes display good current rectification. Correlated scanning electron microscopy (electron-beam induced current and voltage contrast) and transmission electron microscopy reveal that the electrical junction strongly deviates from the linear boundary between the n and p regions defined by ion implantation. Spikes in the junction profile arise from enhanced dopant diffusion along grain boundaries.
Diffusion length of holes in a-Si:H by the surface photovoltage method
Authors: Dresner J. , Szostak D. J. , Goldstein B.
Published: February 2003

The diffusion length L for holes in undoped a-Si:H films has been measured by using a variation of the surface photovoltage method. Values of L in the range 0.33–0.45 μ were found for samples prepared at substrate temperatures Ts = 240 °C and Ts = 330 °C. After prolonged illumination, a reduction to L<0.2 μ was observed; the original value of L was restored after annealing at 200 °C.
A 100 lm/W efficacy low-pressure Xe discharge tube
Authors: Mikoshiba Shigeo , Shirai Shoji , Shinada Shinichi
Published: February 2003

The luminous efficacy of a Zn2SiO4:Mn-coated, low-pressure Xe-positive-column fluorescent tube is found to be as high as 100 l/W which corresponds to an electric to 147-nm radiation energy conversion factor of 66%. This high efficacy can be attained under conditions (pressure)×(column diameter)≃1 Torr cm and (current density)?3 mA/cm2.
The geometry and spectral properties of Ne+3, Ar+3, Kr+3, and Xe+3
Authors: Wadt Willard R.
Published: February 2003

A b initio polarization configuration interaction (POL-CI) calculations show that Ne+3 and Ar+3 are both linear, in agreement with indirect experimental evidence on Ar+3 and in contradiction to earlier approximate theoretical calculations on Ar+3, which predicted an equilateral triangular geometry. The experimentally unknown Ne+3 dissociation energy is predicted to be 0.15±0.01 eV. Simple diatomics-in-molecules (DIM) calculations were shown to be in very good agreement with the ab initio results. DIM calculations predict that Kr+3 and Xe+3 are also linear. All the rare-gas–trimer ions possess at least one very strong absorption band in the visible, even stronger than the near ultraviolet absorption band of the rare-gas–dimer ions.
Longitudinal mode behavior of transverse-mode-stabilized InGaAsP/InP double-heterostructure laser
Authors: Ishikawa H. , Imai H. , Tanahashi T. , Takusagawa M.
Published: February 2003

The longitudinal mode behavior of the transverse-mode-stabilized separated multiclad layer stripe geometry InGaAsP/InP double-heterostructure lasers emitting at 1.3 and at 1.5 μm is examined at 20 °C. The superradiant side modes show that the gain is enhanced on the longer wavelength side of the lasing mode with an increase of the injection current, while the gain is suppressed with energy width of 3 meV on the shorter wavelength side of the lasing mode. The lasing longitudinal mode changes to the longer wavelength mode even under pulsed operation when injection current is increased due to the asymmetric gain spectrum. The result suggests that the intraband relaxation time of quaternary lasers is considerably longer than that of GaAlAs lasers.
Atomic coherence effects in resonant degenerate four-wave mixing
Authors: Lam J. F. , Steel D. G. , McFarlane R. A. , Lind R. C.
Published: February 2003

We present a study of atomic coherence effects in resonant degenerate four-wave mixing. We find for energy levels having magnetic degeneracies, the third-order nonlinear response resulting from two counterpropagating pump waves orthogonally polarized to an incident probe wave generates a signal whose polarization is phase conjugate to that of the incident probe wave. This effect is due to the coupling of different magnetic states resulting from coherent excitation giving rise to a net electric quadrupole. Experimental studies in Na on the D2 line at 5890 Å confirm the analysis.
Polymethyl methacrylate sensitivity variation versus the electronic stopping power at ion lithography exposure
Authors: Mladenov G. M. , Emmoth B.
Published: February 2003

Experimental data for the minimum ion dose D0 during exposure and for the contrast parameter γ are presented. A dependence of D0 on the electronic stopping power but no correlation between D0 and nuclear stopping power is found. An analogical dependence on minimum absorbed electronic stopping energy density is also found. The absorbed energy density for H+ ions is comparable with X-ray lithography data but heavier ions are more effective. For the understanding of these relations an electron excitation spike mechanism is suggested. From the non-Rutherford backscattering experiments at 1.7–1.75 MeV the energy losses of protons in polymethyl methacrylate are found to be 25 eV/nm.
n
+-InP growth on InGaAs by liquid phase epitaxy
Authors: Groves S. H. , Plonko M. C.
Published: February 2003

High-quality epitaxial growth of InP over InGaAs without dissolution has been achieved by using Sn-rich, rather than the more conventional In-rich, solutions. This technique, which produces n+-InP, is directly applicable to growth of p-i-n and avalanche photodiode structures designed for operation in the 1.55-μm wavelength region of minimum loss in optical fibers.
Rapid oxidation via adsorption of oxygen in laser-induced amorphous silicon
Authors: Liu Yung S. , Chiang S. W. , Bacon F.
Published: February 2003

Amorphous silicon has been produced on a single-crystal silicon surface that was exposed to intense pulsed UV-laser radiation at 266 nm. In addition, the formation of an oxide several tens of nanometers in thickness is observed when the irradiation takes place in an O2 or in an air ambient. Various experimental techniques including transmission electron microscopy, sputtered Auger electron spectroscopy, and differential Fourier-transform IR spectroscopy have been employed to characterize the laser-induced amorphous silicon and the oxide layer formed by this rapid melting and resolidification process. The present study suggests a new oxidation phenomena, namely, ’’laser-induced oxidation.’’
Measurement of recombination coefficient in a transverse electric atmospheric CO2 laser gas discharge
Authors: Nundy U. , Shikarkhane N. S. , Chatterjee U. K.
Published: February 2003

The product of recombination coefficient and instantaneous electron density (γne, was measured for a UV-preionized discharge operating at atmospheric pressure for a gas mixture containing CO2, N2, and He in the ratio 1:1:8, over a range of operating field (E/N) from 0.5×10−16 V cm2 to 6.0×10−16 V cm2. This data is used in a computer program to simulate the discharge. Good agreement is observed between experimental current and voltage with those predicted by the program. It was also found that the pulse shapes are critically dependent on γne and this must be accurate to be useful in predicting the behavior of UV-preionized discharges.
High-barrier cluster-free AlxGa1−xAs-AlAs-GaAs quantum-well heterostructure laser
Authors: Coleman J. J. , Dapkus P. D. , Laidig W. D. , Vojak B. A. , Holonyak N.
Published: February 2003

Laser data (77 and 300 K) are presented on an AlxGa1−xAs-AlAs-GaAs quantum-well heterostructure (QWH) grown by metalorganic-chemical vapor deposition with an active region consisting of 13 AlAs barrier layers of size LB∼10 Å and 12 GaAs quantum wells of size Lz∼50 Å. This QWH, which is free of alloy disorder and clustering (Al-Ga clusters) in the active region, emits on the confined particle transitions and not at the lower energies characteristic of QWH’s with AlxGa1−xAs barrier layers (and Al-Ga clusters).
High–gain CO2 laser
Authors: Hara Hiroshi , Fujisawa Akira
Published: February 2003

A high-gain N2-CO2 energy transfer laser using a conical nozzle is described. A small-signal gain of 11 m−1 was obtained at a static pressure of 18.3 Torr. In addition, an output power of 4 W was delivered from an 1.2-cm active length.
Bistable reflection of light by an electro-optically driven interface
Authors: Kaplan Alexander E.
Published: February 2003

A theory of nonresonant optical bistability, based on ’’hybrid’’ interface effect, is developed. This effect occurs upon reflection of light at a single interface of a medium driven by electro-optical feedback. The nonlinear Snell’s and Fresnel’s formulas for the transmission regime are obtained, as well as conditions for bistable operation. The stability of steady states and characteristics of hysteresis jumps are examined as well.
Simulation of high-field transport in GaAs using a Monte Carlo method and pseudopotential band structures
Authors: Shichijo H. , Hess K. , Stillman G. E.
Published: February 2003

We have performed a Monte Carlo simulation of high-field transport in GaAs using a realistic band structure obtained by the empirical pseudopotential method. On this basis, a detailed study of the band structure dependence of impact ionization in GaAs is given. Our method avoids the use of the effective mass theorem or the Kane model of nonparabolicity, which are no longer accurate at high electron energies. We show (i) that the orientation dependence of the impact ionization rate is negligibly small, (ii) that the saturation velocity of electrons in GaAs is close to 6×106 cm/s at extremely high fields (this value is determined to a large extent by the band structure, and (iii) that the previous theories of impact ionization as given by Wolff, Shockley, and Baraff have numerous limitations.
A doping-precipitated morphology in plasma-deposited a-Si:H
Authors: Schiff E. A. , Persans P. D. , Fritzsche H. , Akopyan V.
Published: February 2003

A grossly inhomogeneous, noncolumnar morphology has been observed in doped, plasma-deposited hydrogenated amorphous silicon (a-Si:H) within critical ranges of the diborane to silane ratio in the gas phase. The diborane level can be as low as 5 ppm and depends both on the electrode self-bias potential and the growth rate. Undoped specimens prepared under the same deposition conditions have properties typical of device-grade a-Si:H. These morphology observations suggest a structural origin for some doping-dependent properties in a-Si:H.
Internal photoemission in the anodic oxide/GaAs interface
Authors: Yokoyama S. , Hirose M. , Osaka Y. , Sawada T. , Hasegawa H.
Published: February 2003

The barrier height at the anodic oxide/GaAs interface has been determined by internal photoemission of the metal-oxide-semiconductor structures. The height of the potential barrier between the oxide and GaAs is found to be 2.62±0.05 eV for as-grown and 2.39±0.05 eV for hydrogen-annealed specimens. Quantum yield below the photoemission threshold is interpreted in terms of electron emission from interface states at energies above midgap of GaAs.
Photoluminescence studies of the Mn2+ d-levels in Cd1−xMnxTe
Authors: Vecchi M. P. , Giriat W. , Videla L.
Published: February 2003

We report on the evidence from photoluminescence measurements of the relative positions of the localized d-levels of the Mn2+ ions with respect to the conduction and valence bands of Cd1−xMnxTe. The results indicate that the ground state 6S is approximately 0.8 eV inside the valence band for all compositions up to x=0.7. The first excited state 4G is deep inside the gap, and it represents an energy level that may substantially affect the lifetime and recombination characteristics of the carriers in the Cd1−xMnxTe system.
Phase separation in vapor quench synthesized noncrystalline copper zirconium alloys
Authors: Barbee T. W. , Walmsley R. G. , Marshall A. F. , Keith D. L. , Stevenson D. A.
Published: February 2003

Observations are reported on phase separation in copper-zirconium noncrystalline alloys that were prepared using two-source magnetron-sputtering vapor-quench techniques. The phase separation occurred during synthesis and was observed over the composition range Cu-25–65 at. % Zr. Evidence from x-ray analysis, differential thermal analysis, transmission electron microscopy, and electrochemical behavior are presented. These results are discussed and compared to reported observations on liquid-quenched noncrystalline copper-zirconium alloys.
Production of bulk amorphous Pd77.5Si16.5Cu6 in a containerless low-gravity environment
Authors: Steinberg J. , lord A. E. , Lacy L. L. , Johnson J.
Published: February 2003

Bulk amorphous spheres of Pd77.5Si16.5Cu6, l.5 mm in diameter, have been produced in free-fall containerless solidification. The experiments were conducted in the 32-m drop tube at Marshall Space Flight Center. The samples appear to be at least as stable (if not more so) as those produced during water quench.
Efficient Si solar cells by laser photochemical doping
Authors: Deutsch T. F. , Fan J. C. C. , Turner G. W. , Chapman R. L. , Ehrlich D. J. , Osgood R. M.
Published: February 2003

An ArF excimer laser has been used to form p-n junctions in Si. The laser produces dopant molecules by gas-phase photolysis of an organometallic molecule and simultaneously heats the substrate to allow incorporation of the dopant. Solar cells having conversion efficiencies of 9.6% at AM1 without the use of antireflection coatings have been fabricated from these junctions.
Determination of effective nitrogen concentration in Ga(As,P):N light emitting diodes from photocurrent measurements
Authors: Albrecht H.
Published: February 2003

A room-temperature photocurrent measurement technique is used to determine the effective nitrogen concentration in the active region of GaAs1−xPxN (LED’s) designed for green (x=1), yellow (x=0.85) and orange (x=0.65) light emission. A theoretical expression of the photocurrent signal is presented, which is in good agreement with the experimentally observed behavior of the investigated diodes. The investigation of different vapor phase epitaxy-GaAs1−xPxN LED’s reveals that the external quantum efficiency mainly depends on the product of effective nitrogen concentration and minority-carrier lifetime.
Laser-induced crystallization of silicon islands on amorphous substrates: Multilayer structures
Authors: Biegelsen D. K. , Johnson N. M. , Bartelink D. J. , Moyer M. D.
Published: February 2003

We demonstrate the role and utility of lateral heat flow in the growth of single-crystal silicon islands on amorphous substrates. The thermal profile is varied on and around the islands by controlling the optical absorption using various thin-film structures. In this way, competitive nucleation from edges is suppressed and continued in-plane epitaxial zone growth is enhanced. We have succeeded in producing 20-μm-wide single-crystalline islands.
Novel nonohmic binary composite
Authors: Bhushan Bharat , Kashyap Subhash C. , Chopra K. L.
Published: February 2003

Binary ceramic semiconductor composites, prepared by sintering zinc oxide with barium oxide, exhibit nonohmic behavior owing to the presence of barium oxide. The nonlinearity parameter is strongly dependent on the composition and microstructure of the composite and has a maximum value of 50 for 10-mol % BaO. At BaO concentrations of ⩾50 mol % the composite exhibits ohmic behavior due to the absence of a well-defined two-phase grain-intergranular microstructure.
New technique for resolving charge injection across metal-semiconductor interfaces
Authors: Slowik John H.
Published: February 2003

A new technique has been developed for resolving detailed characteristics of charge injection across metal-semiconductor and other interfaces. This time-resolved charge injection technique uses 0–3 kV pulses, switched at 8 ns, to probe injection barriers in short times compared to dielectric relaxation of the bulk semiconductor. Dark injection from Al contacts into UHV-cleaved CdS is found to approach the theoretical maximum (trap-free space-charge-limited current). Dark injection is reduced by orders of magnitude when monolayers or less of ambient contamination are present at the interface. Conventional steady-state measurements are ineffective in these samples because of bulk trapping.
Correlation of oxygen concentration and activated oxygen donors in silicon crystals on a microscale
Authors: Rava P. , Gatos H. C. , Lagowski J.
Published: February 2003

Concentration profiles of interstitial oxygen were obtained by scanning ir absorption in Si crystals and, upon thermal activation (heat treatment at 450 °C), oxygen donor profiles were determined with spreading resistance measurements on the identical locations of the oxygen profiles. In contrast to the accepted premise, it was found that the oxygen donor concentration is not consistently related to the oxygen concentration, and that in fact the oxygen donor distribution does not necessarily coincide with the oxygen distribution. Vacancy distribution and vacancy gettering defects are believed to be intimately related to oxygen donor activation.
Niobium nitride Josephson tunnel junctions with oxidized amorphous silicon barriers
Authors: Shinoki F. , Shoji A. , Kosaka S. , Takada S. , Hayakawa H.
Published: February 2003

High-quality NbN/NbN Josephson tunnel junctions have been fabricated by rf sputtering. Tunneling barriers are formed by oxidizing amorphous silicon films produced with rf glow discharge deposition. For patterning the base and counter electrode, sputtered ZnO films are employed as a resist mask. The juncitons are found to have large gaps (2ΔNbN) =4.4 mV), to have low leakage current, and to be quite stable for storage and thermal cyclings.
Laser-induced luminescence band in Ge-doped (Al,Ga)As multilayer structures
Authors: Gilgen H. H. , Salathé R. P. , Rytz-Froidevaux Y.
Published: February 2003

A new luminescence band is observed in optically excited (Al, Ga)As multilayer structures that were previously subjected to intense laser irradiation. The band is shifted by 90 meV to a longer wavelength with respect to the band-band recombination of regions not exposed to radiation. The laser power density necessary for processing is 0.55 MW/cm2 for times of ∼100 μsec. The processed region is located at the pn junction with a width of 0.7 and a depth of 0.15 μm.
Chromium-induced up conversion in GaP
Authors: Clerjaud B. , Gendron F. , Porte C.
Published: February 2003

In gallium phosphide, chromium doping allows the excitation of donor-acceptor type luminescence with light whose energy is smaller than the band gap and smaller than the emitted light energy. We discuss the behavior of that emission as a function of the excitation power together with electron paramagnetic resonance results. We conclude that the deep level involved is associated with Cr2+, located 1, 2 eV below the X conduction-band minimum. The up-conversion power efficiency of this sample is also reported.
Generation of shock waves by hot electron explosions driven by a CO2 laser
Authors: Burnett N. H. , Josin G. , Ahlborn B. , Evans R.
Published: February 2003

We observe shock waves with velocity 2.5×106 cm/sec generated by the interaction of a nanosecond CO2 laser at an intensity of 3×1014 W/cm2 with 12–40-μm-thick aluminum foils. It is proposed that these shock waves are not generated by thermal ablation but rather by hot electron heating and explosion of a layer of Al several microns thick adjacent to the target surface. Shock pressures produced by this process are comparable to the highest pressures yet observed by conventional laser driven thermal ablation.
Prebreakdown phenomena between sphere-sphere electrodes in transformer oil
Authors: Kelley Edward F. , Hebner Robert E.
Published: February 2003

Measurements have been made of the propagation velocities of both cathode and anode streamers in transformer oil using sphere-sphere electrodes. Under the conditions of these experiments, the cathode streamer development was a three-step process, while the anode streamer development was a two-step process. The average propagation velocities for the three-steps of the cathode process were 2.4×104, 1.5×105, and 3.9×106 cm/s. The two steps of the anode process propagated at average velocities of 3.8×105 and 4.4×106 cm/s.
Low-temperature ion beam mixing of Al-Sb
Authors: Delafond J. , Picraux S. T. , Knapp J. A.
Published: February 2003

The mixing of Sb layers on Al by 400-keV Xe ions at 80 K has been investigated. A tail in the Sb concentration profile is observed to move into the Al substrate to the depth of the Xe range. The quantity of mixed Sb in the tail increases linearly with Xe fluence. No growth of layers corresponding to a binary compound is observed. However, the Sb concentration in the original layer drops continuously until the concentration reaches the first equilibrium compound phase, AlSb. The present results are believed to demonstrate pure collisional mixing of Sb into Al without the competing effects of enhanced diffusion since (i) vacancies are immobile in Al at 80 K and (ii) the observed rate of mixing, ≃2.5 Sb per Xe, is consistent with recent theoretical estimates of collisional mixing due to ion recoil and ion cascade events.
Formation of silicon nitride structures by direct electron beam writing
Authors: Chin Brymer H. , Ehrlich Gert
Published: February 2003

Localized deposits of silicon nitride are formed under ultrahigh vacuum conditions by electron bombardment of nitrogen molecularly bound on Si (100) at low temperatures (T⩽ 50 K). Auger spectra of the deposits reveal no impurities and have the same essential features as spectra from silicon nitride produced by conventional chemical vapor deposition.
Lifetime measurement in Hg0.7Cd0.3Te by population modulation
Authors: Mroczkowski J. A. , Shanley J. F. , Reine M. B. , LoVecchio P. , Polla D. L.
Published: February 2003

A new contactless optical modulation technique for the determination of photogenerated carrier lifetimes in semiconductors is presented. The technique consists of measuring the modulation in the transmitted intensity of a dc probe beam (h/ω<Eg) due to a modulated pump beam (h/ω≳Eg). The fractional change in the probe beam transmission is proportional to the excess carrier lifetime. Data are presented for lifetimes of 0.1–4 μ sec measured by this technique in p-type and near-intrinsic Hg0.7Cd0.3Te samples at 300 K.
Observation of the amorphous-to-crystalline transition in silicon by Raman scattering
Authors: Kamiya T. , Kishi M. , Ushirokawa A. , Katoda T.
Published: February 2003

Raman scattering, electron diffraction, and dark-conductivity measurements have been made on so-called a-Si films deposited at various rf powers by a glow-discharge technique. These measurements show that an abrupt transition between amorphous and polycrystalline states occurred between 350 and 370 rf voltages and films deposited at high rf voltages are polycrystalline. Dark conductivity of the silicon films changed largely with the amorphous-to-crystalline transition. It is also observed that some polycrystallized silicon films exhibited new peaks between 505 and 513 cm−1 in the Raman spectra.
Possible observation of the ion-resonance instability in a non-neutral electron cloud
Authors: Eckhouse S. , Fisher A. , Rostoker N.
Published: February 2003

Experimental observations which are consistent with the occurrence of the ion-resonance instability in a non-neutral electron cloud confined in a magnetic mirror are reported. The instability is observed on electronstatic probes exhibiting signals which correspond to a positive oscillating charge. The ion oscillation is along the axis of the mirror field.