bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric function of coevaporated Co-Al2O3 cermet films
Authors: Niklasson G. A. , Granqvist C. G.
Published: February 2003

The dielectric function of well characterized granular Co-Al2O3 films, produced by e-beam coevaporation, is reported for the 0.3–40-μm range. The data are interpreted within the Maxwell-Garnett formalism. Effects of atomic Co dispersed in the Al2O3 matrix and of multipole coupling among the Co particles are discussed.
Electrolyte electroreflectance study of laser annealing effects on the CdTe/Hg0.8Cd0.2Te (111) system
Authors: Amirtharaj P. M. , Pollak Fred H. , Waterman J. R. , Boyd P. R.
Published: February 2003

We have investigated the effects of laser annealing on the CdTe/Hg0.8Cd0.2Te (111) system by measuring the electrolyte electroreflectance (EER) spectra from both the CdTe layer as well as the interface region. The sample was a Hg0.8Cd0.2Te (111) single crystal with a 500-Å-thick polycrystalline CdTe film deposited on it; a section of the interface was annealed using the neodymium: yttrium aluminum garnet (Nd:YAG) laser 1.06-μm line. Our observations indicate the presence of strain due to lattice mismatch at the interface; laser annealing relieves this strain. In addition, the annealing also causes the diffusion of Hg ions from the interfacial region into the passivant layer. The changes in the line shapes of the EER spectra also show an improvement in the crystalline quality of the passivant layer.
Relation of stimulated and spontaneous transitions in tunneling structures to the elastic current-voltage characteristic
Authors: Whiteley S. R. , Xie L. Z. , Hemphill R. , Gustafson T. K.
Published: February 2003

The stimulated emission and absorption of surface plasma modes by inelastic scattering of tunneling electrons is considered. It is shown that the net absorption rate is proportional to the current difference between points ±ℏω/e about the bias point on the elastic current-voltage characteristic. In particular, this can be negative implying the possibility of net stimulated emission over a large bandwidth. The relationship to photon assisted tunneling theory is considered.
An enhancement mode Schottky barrier gate charge-coupled device on a high electron mobility transistor structure
Authors: Liu Y. Z.
Published: February 2003

An enhancement mode charge-coupled device (CCD) was fabricated for the first time on a selectively doped n-GaAlAs/p−-GaAs heterojunction structure. A dramatic improvement in charge-transfer efficiency (CTE) was observed as the CCD is cooled from 300 to 77 °K. This improvement is attributed to the increase in low field electron mobility of the two-dimensional electron gas at low temperature. Charge capacity was also found to increase upon cooling. The cause is not well understood. An optimized structure for high-speed CCD is proposed.
Logic delays of 5-μm resistor coupled Josephson logic
Authors: Sone J. , Yoshida T. , Tahara S. , Abe H.
Published: February 2003

Logic delays of resistor coupled Josephson logic (RCJL) have been investigated. An experimental circuit with a cascade chain of ten RCJL OR gates was fabricated using Pb-alloy Josephson IC technology with 5-μm minimum linewidth. Logic delay was measured to be as low as 10.8 ps with power dissipation of 11.7 μW. This demonstrates a switching operation faster than those reported for other Josephson gate designs. Comparison with computer-simulation results is also presented.
Photoelectrochemical cells based on GaAs0.6P0.4 epilayers: Stabilization and luminescent properties
Authors: Hobson William S. , Ellis Arthur B.
Published: February 2003

Stable, efficient photoelectrochemical cells (PEC’s) have been constructed from an n-type material used in light-emitting diode (LED) fabrication. The photoelectrode, which consists of an epilayer of GaAs0.6P0.4 on a graded layer terminating in a GaAs substrate, can be used in a PEC employing aqueous ditelluride electrolyte to convert 457.9-nm light to electrical energy with efficiencies which routinely exceed 16% at incident intensities of ∼10 mW/cm2. Photoluminescence from these electrodes can be substantially quenched by the passage of photoanodic current during PEC operation.
Carrier lifetime measurement for determination of recombination rates and doping levels of III-V semiconductor light sources
Authors: Su C. B. , Olshansky R.
Published: February 2003

A novel method is described for measuring the carrier lifetimes in double heterostructure light-emitting diodes (LED’s) and lasers. The improved resolution of the technique permits the first reported measurement of the carrier dependence of the radiative recombination coefficient. The technique also provides a reliable measurement of the active region doping level which is in very good agreement with the values calculated from the composition of the growth solutions.
Optical guided-wave interactions with magnetostatic waves at microwave frequencies
Authors: Fisher A. D. , Lee John N. , Gaynor E. S. , Tveten A. B.
Published: February 2003

Interaction of guided optical waves with microwave magnetostatic waves in yittrium iron garnet thin films has been demonstrated. TM↔TE mode conversion induced by codirectional (and contradirectional) magnetostatic waves was experimentally observed with conversion efficiencies of up to 4%. Theoretical expressions for this interaction are given and compared with observations. The thin-film geometry demonstrated could make a practical number of optical signal processing devices in the 1–20-GHz range.
Sources of photoionization in transversely excited atmospheric CO2 lasers
Authors: Scott S. J. , Smith A. L. S.
Published: February 2003

The existence of two sources of the photionization in UV preionized sealed CO2-N2-He-(CO) lasers has been established. One is steadily created in the laser gas mixture by the electrical discharge and is identified as NO and NO2. The second source is associated with an impurity in any CO gas used as part of the initial gas mixture.
Bound-free emission in HgBr
Authors: Lapatovich Walter P. , Gibbs George R. , Proud Joseph M.
Published: February 2003

We report the first experimental observation of bound-continuum fluorescence in the mercuric bromide system. HgBr (B2Σ+) population is created in ultraviolet photodissociative excitation of the dihalide. The resulting bound-free fluorescence (B2Σ+→A2Π) is detected over a bandwidth of ≂120 nm centered at 685 nm. The associated and well known bound-bound fluorescence (B2Σ+→X 2Σ+) is also seen. A semiclassical computer code has been developed to predict the transition probability density for the observed bound-free features.
Arc lamp zone melting and recrystallization of Si films on oxidized silicon substrates
Authors: Stultz T. J. , Gibbons J. F.
Published: February 2003

A high pressure mercury arc lamp focused into a narrow ribbon beam has been used to recrystallize thin films of polysilicon deposited on thermally grown silicon dioxide. The recrystallized films contain grains that are typically 0.5–1 mm in width and several centimeters long. Surface texture measurements show the crystallites to be almost entirely 〈100〉 in the plane of the film with the orthogonal 〈100〉 direction closely paralleling the scan direction.
Model of backsurface gettering of metal impurities in silicon
Authors: Vengurlekar Arvind S.
Published: February 2003

Metallic impurities can degrade silicon devices in many ways, and various gettering techniques are therefore used to immobilize these atoms at the backsurface of the wafer. A solution to the relevent diffusion equations is given here and used to obtain a simple formula relating the gettered atom density to the gettering temperature and time with the metal diffusivity in silicon as the main input. The model reproduces experimental trends quite well.
Analysis of low-pressure chemical vapor deposited silicon nitride by Rutherford backscattering spectrometry
Authors: Hwang H. L. , Hwu C. C. , Liue J. C. , Lin H. H.
Published: February 2003

Rutherford backscattering spectrometry channeling was found effective in composition and impurity analysis of silicon nitride films, and conditions to deposit stoichiometric Si3N4 by low-pressure chemical vapor deposition are obtained. The as-determined N/Si ratio is not correlated with the measured refractive index, and a possible interpretation is discussed. Also, the inhomogeneity problem of the nitride films is examined.
Tunable electroluminescence from GaAs doping superlattices
Authors: Künzel H. , Döhler G. H. , Ruden P. , Ploog K.
Published: February 2003

The first observation of strongly tunable electroluminescence from a new type of semiconductor superlattice is reported. We achieved a shift of the electroluminescence peak energy by several hundred millielectron volts below the gap of pure GaAs, when electrons and holes are injected over long distances via selective electrodes. This directly reflects the tunability of the indirect gap in real space, which is a unique feature of doping superlattices. The results further demonstrate that with increasing doping concentration of the constituent superlattice layers the luminescence frequency can be tuned over an even wider range. This behavior agrees well with our calculations.
Evidence for the creation of the main electron trap in bulk GaAs
Authors: Martin G. M. , Terriac P. , Makram-Ebeid S. , Guillot G. , Gavand M.
Published: February 2003

Ikoma and Tanigushi have recently proposed a procedure consisting of O or As ion implantation followed by a 600 °C anneal to create a midgap electron trap in GaAs. The question of the definite identification of this level with the native level EL2, the main electron trap always observed in bulk and vapor phase epitaxial materials, remained open. To answer this question, we performed photocapacitance transient experiments. In these experiments, the presence of EL2 is revealed unambiguously by an overshoot behavior in the photocapacitance transients. We have reproduced the experiment of Tanigushi and Ikoma using O, B, and Ne as implanted species. Our experiment has established that EL2 is created by O, B, or Ne implantation in bulk GaAs. When the same procedure is repeated with liquid phase epitaxial material, an electron trap is created at approximately the same energy level but the photocapacitance transient experiment shows that this level does not have the same properties as EL2.
Photon enhanced oxidation of silicon
Authors: Young Edwin M. , Tiller William A.
Published: February 2003

Experiments have been conducted to show that at low laser power densities the enhanced oxidation rate of silicon is linearly proportional to the photon flux density for photon energies in the range 2.4–2.7 eV. The enhancement effect is greater for 〈100〉 Si than for 〈111〉 Si.
Growth of high-purity GaAs layers by molecular beam epitaxy
Authors: Hwang J. C. M. , Temkin H. , Brennan T. M. , Frahm R. E.
Published: February 2003

High-purity GaAs layers were grown by molecular beam epitaxy using carefully controlled procedures for source and substrate preparation as well as the growth itself. The layers grown without intentional doping were semi-insulating with resistivities consistently greater than 106 Ω cm. The layers doped with Si in the 1014 cm−3 range gave record Hall mobilities, the highest value being 140 000 cm2/Vs at 55 K with a net charge carrier concentration of 1×1014 cm−3. The results suggest that the use of prolonged growth period or AsH3 source is not a necessary condition for high-purity growth.
Single-mode operation of coupled-cavity GaInAsP/InP semiconductor lasers
Authors: Ebeling K. J. , Coldren L. A. , Miller B. I. , Rentschler J. A.
Published: February 2003

Monolithic two-section GaInAsP/InP lasers are shown to operate in a single longitudinal mode under high-speed pulsed current modulation. The length of the emitted monomode light pulses is less than 500 ps. The suppression of secondary modes is described in a rate equation model that is generally useful for a variety of coupled-cavity configurations. It is found that 10% increase in cavity loss for the unwanted modes is sufficient to provide 17 dB suppression.
Monte Carlo simulation of impact ionization in GaAs including quantum effects
Authors: Chang Yia-Chung , Ting D. Z. -Y. , Tang J. Y. , Hess K.
Published: February 2003

We present a theory of steady-state impact ionization in GaAs including a realistic band structure and the electron-phonon interaction using a field-theoretic scheme that goes beyond first order processes. The theory explains most known experimental high-field transport data for GaAs satisfactorily, except for the anisotropy of the impact ionization rate measured by Pearsall. It is concluded that this anisotropy is not connected to quantum effects influencing the scattering rate and is probably caused by transient phenomena at the metallurgical junction of the samples used for investigating the anisotropy of the ionization rate.
Picosecond carrier dynamics in optically illuminated glow discharge hydrogenated amorphous silicon
Authors: Komuro Shuji , Aoyagi Yoshinobu , Segawa Yusaburo , Namba Susumu , Masuyama Akio , Okamoto Hiroaki , Hamakawa Yoshihiro
Published: February 2003

We have found that a picosecond time relaxation of photoexcited carriers appears after an optical illumination in glow discharge hydrogenated amorphous silicon. The origin of this rapid relaxation is qualitatively explained by the relaxation of excited carriers to increased shallow localized states after the optical illumination. The experimental results have been analyzed by a multiple trapping mechanism taking into account shallow and deep localized states.
Low-temperature silicon crystal growth on an amorphous planar substrate
Authors: Mori Hidefumi
Published: February 2003

Silicon single crystal film having an area of aobut 130×130 μm2 was grown on an amorphous planar substrate. Crystal growth was performed by silicon evaporation on the substrate, which was covered by gold film and maintained at 380 °C. The gold film, which is shaped in a periodic rhomboidal pattern, controls the crystallographic orientation. Transmission electron microscope/diffraction observation showed that the 〈111〉 axis was normal to the substrate, and the 〈11̄0〉 axis was normal to a side of the gold rhomboid pattern.
Surface chemical reactions on In0.53Ga0.47As
Authors: Stocker H. J. , Aspnes D. E.
Published: February 2003

Dark currents on In0.53Ga0.47As mesa photodiodes can be reduced significantly by treating the surfaces with H2SO4:H2O2:XH2O (10≤X≤500) instead of the usual bromine-methanol etch. Using spectroscopic ellipsometry we show that peroxide etches form porous amorphous As or oxide overlayers according to whether the pH values are less than or greater than ∼3. The identity of these overlayers is established by their dielectric response and chemical reactivity.
Soft x-ray pumping of metastable levels of Li+
Authors: Caro R. G. , Wang J. C. , Falcone R. W. , Young J. F. , Harris S. E.
Published: February 2003

Soft x rays from a plasma generated by a neodymium: yttrium aluminum garnet laser beam (1.06 μm) are used to photoionize neutral Li vapor to produce Li+ metastables. Maximum metastable densities of Li+ (1s2s) 1S=6×1014 ions/cm3 and Li+ (1s2s) 3S=3×1015 ions/cm3 are obtained. The effective lifetimes of these levels are measured to be approximately 5 ns. At 50 mJ of incident laser energy the inferred conversion efficiency from 1.06-μm radiation to soft x rays is ∼14%.
Polarization coupling effects in transversely excited atmospheric CO2 lasers: Application to single axial mode operation
Authors: Kar A. K. , Harrison R. G. , Tratt D. M. , Emshary C. A.
Published: February 2003

We report the observation of anomalous polarization coupling effects occurring in injection-locked transversely excited atmospheric (TEA) CO2 lasers, deduced from studies of the injection detuning parameter under varying conditions of polarization and injection power. For the special case of injection with orthogonally polarized radiation we have determined the existence of an optimum operation point, exhibiting minimum sensitivity of single mode operation to the detuning parameter. Off-resonance injection locking of untuned TEA cavities is also discussed.
Influence of lateral waveguiding properties on the longitudinal mode spectrum for semiconductor lasers
Authors: Stegmüller Bernhard
Published: February 2003

The direct dependence of the longitudinal mode spectrum on active and passive waveguiding and stripewidth of metal-cladded ridge-waveguide-stripe lasers is presented. Since the investigated lasers originate from the same epitaxial wafer, the influence of other laser parameters, such as layer characteristics and material quality, can be neglected. Experimental results agree well with a theory, based on the spontaneous emission coefficient as the dominant parameter, which is affected by the curvature of wave fronts.
Improved lifetimes of (GaAl)As visible (740 nm) lasers by reducing bonding stress
Authors: Hayakawa T. , Miyauchi N. , Yamamoto S. , Hayashi H. , Yano S. , Hijikata T.
Published: February 2003

It is shown that the active layer stress caused by the bonding process can be reduced by setting the thicknesses of the cap layer and the substrate at the appropriate values. The life test of the (GaAl)As V-channeled substrate inner stripe lasers emitting at 740 nm, 50 °C demonstrated that the lifetime is considerably improved by the introduction of the thick cap layer (∼40 μm) and the thinned substrate (∼80 μm).
Observation of multiconfigurations for a vortex mode in long Josephson tunnel junctions
Authors: Scheuermann M. , Chen J. T.
Published: February 2003

Symmetric vortex-antivortex and asymmetric vortex-vortex modes have been observed in long Josephson tunnel junctions. These two modes manifest themselves as two nearly identical resistive branches in the current-voltage characteristics. The voltage spacing between the symmetric vortex-antivortex and the asymmetric vortex-vortex modes is only about 3% of the voltage spacing between the first and second resistive branches. Except for a slight displacement in current these two modes almost completely overlap in voltage and current.
Interface states in GaAs/AlxGa1−xAs heterostructures grown by organometallic vapor phase epitaxy
Authors: Matsumoto Takashi , Bhattacharya Pallab K. , Ludowise M. J.
Published: February 2003

The GaAs/AlxGa1−xAs interface grown by organometallic vapor phase epitaxy has been studied by transient capacitance techniques. No electron emissions have been observed from deep states at or near the interface of a GaAs/Al0.2Ga0.8As junction. Highly nonexponential transients were recorded for emissions near the interface, which arise from states with an apparent activation energy of 0.15 eV. Dominant deep traps were detected in the GaAs and Al0.2Ga0.8As in regions away from the interface. The implications of the results have been discussed.
Effect of argon implantation on the activation of boron implanted in silicon
Authors: Milgram A. , Delfino M.
Published: February 2003

Argon ions were implanted either prior or subsequent to an ion implantation of boron into silicon wafers. After isochronal annealing at temperatures ranging from 500 to 900 °C, the samples were examined by a spreading resistance-carrier concentration profile and secondary ion mass spectroscopy. It is shown that argon implantation at a dose sufficient to produce an amorphous layer inhibits the electrical activation and diffusion of boron implanted in silicon.
Specific site location of S and Si in ion-implanted GaAs
Authors: Bhattacharya R. S. , Pronko P. P. , Ling S. C.
Published: February 2003

Rutherford backscattering and proton induced x-ray emission in combination with channeling have been used to investigate the specific site location of S and Si implanted in GaAs through the asymmetry in their channeling dips. A pronounced asymmetry is observed for 〈110〉 scans parallel to the {11̄0} plane in the case of S, whereas no such asymmetry is found for the case of Si. These results clearly indicate that S predominantly occupies one sublattice site which is shown to be the As site whereas Si occupies both Ga and As sites in about equal concentrations.
High mobility in liquid phase epitaxial InGaAsP free of composition modulations
Authors: Quillec Maurice , Benchimol Jean-Louis , Slempkes Serge , Launois Huguette
Published: February 2003

InxGa1−xAsyP1−y epilayers lattice matched to InP were grown from the liquid phase at temperatures far above the commonly used temperature range. The goal was to get off the unstable region corresponding to compositions emitting in the wavelength range of 1.2 μm<λ<1.5 μm at 650 °C. In0.71Ga0.29As0.65P0.35 (λ=1.35 μm) layers thus grown have the highest electron Hall mobilities ever obtained in this material: μ300 K =7000 cm2/Vs and μ77 K =23 200 cm2/Vs for ND−NA =8.1014 cm−3. We suggest that a contribution to mobility limitation might be related to the composition modulations present in epilayers grown in the usual temperature range.
Extremely rapid outdiffusion of n-type impurities in InP
Authors: Chin A. K. , Camlibel I. , Dutt B. V. , Swaminathan V. , Bonner W. A. , Ballman A. A.
Published: February 2003

During sealed ampoule annealing at 550 °C, an unexpected, deep diffuson front was observed in n-type InP crystals using defect etching and cathodoluminescence (CL) imaging. The diffusivities of the fronts were determined to be 1–5×10−8 cm2 s−1 which is approximately two orders of magnitude greater than that of the rapidly diffusing Zn impurity. By measuring the changes in the CL intensity and the photoluminescence linewidth to determine the changes in carrier concentration, the diffusion fronts were shown to be caused by the outdiffusion of the dopants. Although outdiffusion of Cr and Fe, affecting an ∼1 μm surface region during thermal annealing at 550 °C for 30 min, has previously been reported for InP, we believe this is the first reported observation of rapid outdiffusion of n-type impurities that can affect InP crystals to a substantial depth (∼200 μm) for similar annealing conditions.
A fundamental noise limit for biased resistors at low temperatures
Authors: Arai Makoto R.
Published: February 2003

A biased resistor at low temperature T is modelled by a degenerate Fermi gas whose electrons scatter from phonons in thermal equilibrium and impurities while moving in the presence of a finite electric field E. A nonperturbative solution of the Boltzmann equation valid for thin films yields a Fermi-like steady state distribution characterized by an effective temperature T* (>T). For large fields the energy scale (T*) is set by the energy (eEl*) absorbed in an inelastic mean free path (l*∝T*−3/2). This yields T* proportional to E2/5. At low temperatures and frequencies the Johnson noise temperature is T*, independent of the bath temperature for large fields.
Spectral dependence of reversible optically induced transitions in organometallic compounds
Authors: Benson R. C. , Hoffman R. C. , Potember R. S. , Bourkoff E. , Poehler T. O.
Published: February 2003

Optical switching in the class of semiconducting organometallic films such as copper and silver tetracyanoquinodimethane (CuTCNQ and AgTCNQ) can be erased using CO2 laser radiation. The effect can be observed by Raman spectroscopy and direct observation. Results on the wavelength and irradiance dependence of the optical switching threshold are also presented and interpreted in light of proposed switching mechanisms in these organic materials.
Bistability and slow oscillation in an external cavity semiconductor laser
Authors: Stallard W. A. , Bradley D. J.
Published: February 2003

Reproducible bistable and hysteretical behavior is obtained from an external cavity laser, with one absorbing and one gain semiconductor diode, when the absorber diode is operated below its transparency threshold current density. The laser diodes are optically coupled without parasitic conductance or photoconductive electrical coupling and the bistable laser operates in a single longitudinal mode. Under certain conditions the laser oscillates at around 20 Hz with millisecond optical switching times.
Amorphization of germanium, gallium phosphide, and gallium arsenide by laser quenching from the melt
Authors: Cullis A. G. , Webber H. C. , Chew N. G.
Published: February 2003

The direct formation of amorphous layers on (111) Ge, GaP, and GaAs crystals is demonstrated to occur when these are transiently melted with 2.5-ns UV laser pulses below particular radiation energy density thresholds. Above these thresholds, the melt resolidification rate is reduced and in each case the (111) crystals exhibit a transition to a regime of profuse twin defect nucleation. Also for each material, laser melting of (001) crystal leads to defect-free recrystallization when amorphization does not occur. All amorphous layers exhibit a cellular thickness modulation which may be due to a fundamental instability in the recrystallization interface.
Surface acoustic wave quasi-zero-temperature cuts in Ba2NaNb5O15
Authors: Hénaff Jeannine , Feldmann Michel
Published: February 2003

Surface acoustic wave properties of Ba2NaNb5O15 crystals are investigated in terms of electromechanical coupling coefficient k2 and frequency temperature coefficients. A X-rotated cut and a Y-rotated cut are selected for their fair coupling. Experimental verifications on a Union Carbide Ba2NaNb5O15 crystal proved excellent agreement for the coupling (1.2%) and markedly better results than computed for the frequency-temperature coefficient. The best value is measured to be as low as 1.5 ppm/K for 〈101〉 cut, (1̄01) propagation.
Passive phase conjugate mirror based on self-induced oscillation in an optical ring cavity
Authors: Cronin-Golomb Mark , Fischer Baruch , White Jeffrey O. , Yariv Amnon
Published: February 2003

A passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described. Unlike previously demonstrated passive phase conjugate mirrors it generates only one of its pumping beams by nonlinear optical interactions, the other being provided by feedback of the probe after transmission through the nonlinear medium. The results of a theory yielding phase conjugate reflectivity and oscillation thresholds are presented together with an experimental demonstration of phase conjugation in barium titanate and strontium barium niobate. The device is self-starting by four-wave mixing, and has an oscillation threshold lower than that of other previously demonstrated passive phase conjugate mirrors with similar ease of alignment. The operation of a device which generates nonconjugate oscillation beams is also reported.
New current injection 1.5-μm wavelength GaxAlyIn1−x−yAs/InP double-heterostructure laser grown by molecular beam epitaxy
Authors: Tsang W. T. , Olsson N. A.
Published: February 2003

We have prepared and characterized for the first time a new current injection double-heterostructure (DH) laser with GaxAlyIn1−x−y As as the active layer and InP as the cladding layers operating at 1.5-μm wavelength. In this new heterostructure, there is only one group V element involved in every layer. This eases the precise control of lattice matching during molecular beam epitaxial (MBE) growth. At the same time, it eliminates the use of Al0.48In0.52 As, which is of lower quality than InP when grown by MBE, as the cladding layers. Broad-area Fabry–Perot diodes of 380×200 μm have a threshold current density of ∼3.2 kA/cm2 for active layer thickness of 0.25 μm. In the temperature range ∼15–50 °C, the threshold temperature dependence coefficient T0 is typically ∼40 K. Above ∼50 °C, T0 decreases to ∼25–35 K. The present laser also represents the first current injection DH laser emitting at 1.5 μm ever prepared by MBE. In the present experiment, As2 instead of As4 was also used for the first time in growing the GaxAlyIn1−x−y As layers by MBE in order to improve their quality. This becomes particularly important as the substrate growth temperatures employed are relatively low, ≲625 °C.
Absolute measurement of optical attenuation
Authors: Wetsel Grover C. , Stotts Steven A.
Published: February 2003

We have discovered that laser beam deflection spectroscopy can be used for the absolute measurement of wave or particle beam attenuation in condensed matter. The concept has been experimentally evaluated by successfully measuring the absolute optical attenuation in a crystal of U3+:CaF2 at 514 nm. A theoretical model that explains the experiment and characterizes the range of applicability of the method has been developed.
Surface and interface nitridation of thin polycrystalline silicon films
Authors: Habraken F. H. P. M. , Kuiper A. E. T. , Tamminga Y.
Published: February 2003

Polycrystalline silicon thin films (about 800 Å thick) on silicon dioxide, annealed in ammonia at 1160 °C for various times, have been analyzed using Auger electron spectroscopy in combination with argon ion sputtering and Rutherford backscattering spectrometry. Nitridation results in the growth of surface nitride layers of the same thickness as on monocrystalline silicon. However, nitridation times longer than 30 min give rise to an additional (oxy)nitride formation at the polysilicon/silicon dioxide interface. The degree of coverage of the grain boundary surface by nitrogen is estimated to be well below monolayer level.
Thermal and pulsed laser evaporation of single phase AsxP1−x alloys
Authors: Schwartz G. P. , Bondybey V. E. , English J. H. , Gualtieri G. J.
Published: February 2003

The atomic and molecular species evolved during thermal and pulsed laser evaporation of single phase AsxP1−x alloys have been examined using mass spectroscopy. Thermal evaporation yields tetratomic molecules of the form As4−nPn (n=0, 1, 2, 3, 4) as well as diatomic As2, P2, and AsP. Pulsed laser vaporization using a Q-switched train of 1.06-μ neodymium: yttrium aluminum garnet (Nd:YAG) pulses primarily evolves atomic As and P species, some fraction of which are ionized. The generation of atomic beams containing one or more of the group V elements from a homogeneous source of controllable stoichiometry has some potential applications for the growth of optoelectronic thin films.
Determination of diffusion length of electron beam induced minority carriers in polycrystalline GaAs
Authors: Paz O. , Borrego J. M.
Published: February 2003

A method of combining Schottky barrier electron beam induced current imaging of grain clusters with quantitative determination of diffusion length is demonstrated. This was achieved by comparing the measured number of collected carriers per incident electron, corrected for backscattered, and secondary electrons to a calculated value. A source function compensated for metal thickness was used. Diffusion lengths were measured in GaAs samples and ranged from 0.2 μm for polycrystalline and bulk single crystal material to 7.5 μm for chemical vapor deposition grown layers. These values were independently verified through a comparison with quantum efficiency data.
Optically enhanced amorphous silicon solar cells
Authors: Deckman H. W. , Wronski C. R. , Witzke H. , Yablonovitch E.
Published: February 2003

We describe the first application of optical enhancement to thin-film (∼0.75 μm thick) amorphous silicon solar cells and define cell geometries which maximize enhancement effects. We observed that due to the improved infrared absorption the external AM1 short circuit current increases by 3.0 mA/cm2 in cells constructed in accordance with the principles of optical enhancement.
Fabrication of GaAs-Mo-Si structures by metalorganic chemical vapor deposition and laser annealing
Authors: Okamoto K. , Imai T.
Published: February 2003

Undoped-polycrystalline GaAs layers were deposited on Mo layers by metalorganic chemical vapor deposition and annealed by pulse laser irradiation. The laser used here was a Q-switched ruby laser and the annealing was done by immersing the samples in SnCl2-dissolved methanol. Then, recrystallization and doping of the GaAs layers were successfully done. The Schottky characteristics were observed between the top GaAs layer and the Mo layer underneath; the barrier height was 0.53 eV.
Picosecond CdSe photodetector
Authors: Margulis W. , Sibbett W.
Published: February 2003

The performance of a photoconductive device in which an evaporated CdSe film is used as the semiconductor medium is described. The results indicate an ultrafast response and a recovery time ∼20 ps.
Measurement of deep levels in hydrogenated amorphous silicon by transient voltage spectroscopy
Authors: Johnson N. M.
Published: February 2003

Electronic defect levels in amorphous silicon Schottky diodes have been measured by capacitance transient spectroscopy performed in the constant capacitance mode. In hydrogenated amorphous silicon deep levels are continuously distributed in energy and of sufficient density to dominate the electrical properties. The constant capacitance mode, applied for the first time to an amorphous semiconductor, offers significant advantages over the transient capacitance mode for measuring the bulk density of gap states. For example, numerical solution of Poisson’s equation for only the steady-state charge distribution is required to analyze the transient response of a diode after a trap-filling voltage pulse. The technique has been used to record time-resolved transients, which saturate with respect to pulse width, and the analysis yields deep level distributions in the range of 1017 eV−1 cm−3 over the energy interval from 0.6 to 0.9 eV below the conduction-band mobility edge.
Electrical characteristics of amorphous iron-tungsten contacts on silicon
Authors: Finetti M. , Pan E. T-S. , Suni I. , Nicolet M-A.
Published: February 2003

The electrical characteristics of amorphous Fe-W contacts have been determined on both p-type and n-type silicon. The amorphous films were obtained by cosputtering from a composite target. Contact resistivities, ρc=1×10−7 and ρc=2.8×10−6, were measured on n+ and p+ silicon, respectively. These values remain constant after thermal treatment up to at least 500 °C. A barrier height, φBn=0.61 V, was measured on n-type silicon.
Strongly bound chemisorption state for benzene on silicon (111)
Authors: Piancastelli M. N. , Cerrina F. , Margaritondo G. , Franciosi A. , Weaver J. H.
Published: February 2003

Dramatic differences were observed between the room-temperature reactivity of benzene on cleaved Si and on cleaved Ge and GaAs with synchrotron-radiation photoemission. No evidence of benzene adsorption was observed on Ge or GaAs. On Si we unexpectedly observed a strongly bound state, probably due to the formation of phenylic-like C–Si bonds.
Crystal growth in amorphous silicon thin films induced by incoherent light flashes
Authors: Tong B. Y. , Ebihara K. , John P. K. , Wong S. K. , Chik K. P.
Published: February 2003

Amorphous silicon thin films on glass substrates were crystallized by a 4-μs light pulse from a plasma arc. Explosive crystal growth from nucleation centers was observed at 4.6 J/cm2. Large silver-shaped streaks (0.7 mm×50 μm) were produced. Conductivity changed by six orders of magnitude and the flashed samples gave high photoconductivity. Growth patterns were different near the threshold value of 3.1 J/cm2.
Photoelectrocatalysis on silicon in solar light
Authors: Szklarczyk Marek , Bockris John O’M.
Published: February 2003

Photoelectrochemical measurements have been carried out on p-Si electrodes which contained islands of Pb, Cd, Au, Ni, Co, and Pt. These islands cause the photocurrent density of some of the Si systems to increase greatly (10×) in the middle region of the photocurrent potential curve. A plot of the change in potential observed for this region against log i0 for the dark hydrogen evolution on the metals concerned is linear with a slope close to that expected for a rate determining step at the metal-solution interface.
Ultrahigh speed modulation-doped heterostructure field-effect photodetectors
Authors: Chen C. Y. , Cho A. Y. , Bethea C. G. , Garbinski P. A. , Pang Y. M. , Levine B. F. , Ogawa K.
Published: February 2003

We have developed a sensitive, ultrahigh speed photodetector which has a structure of a modulation-doped AlxGa1−xAs/GaAs field-effect transistor. In spite of a large gate-drain spacing of >8 μm and a gate length of >20 μm, this detector exhibited a rise time of 12 ps and a full width at half-maximum of 27 ps. When tested by a 8200-Å GaAs injection laser, the detector showed an ac (>20 MHz) external quantum efficiency of >630%, i.e., 9 times more sensitive than a pin photodiode. In view of its high sensitivity, ultrahigh speed, and compatibility with modulation-doped field-effect transistors, this detector has promise for a variety of high-speed optical applications.
UV laser photopolymerization of volatile surface-adsorbed methyl methacrylate
Authors: Tsao J. Y. , Ehrlich D. J.
Published: February 2003

The localized UV laser photopolymerization of surface-adsorbed methyl methacrylate has been used to deposit poly(methyl methacrylate) films for direct patterning of wet and dry chemical etching processes. Using this negative resist process, submicrometer linewidths both in the polymer deposition and in pattern transfer into Si and SiO2 have been demonstrated. The chemical kinetics of simple and catalyzed photopolymerization have been studied by dynamic lensing experiments and modeled as a dynamic equilibrium between competing surface photoreactions.
Transient single-longitudinal mode stabilization in double active layer GaInAsP/InP laser under high-bit rate modulation
Authors: Tsang W. T. , Olsson N. A. , Logan R. A.
Published: February 2003

We propose and demonstrate the operation of a new 1.3-μm wavelength GaInAsP semiconductor laser: the double active layer (DAL) crescent laser and compared its device performances with regular single active layer (SAL) crescent laser fabricated under similar procedures. While the regular SAL crescent lasers (∼250 μm cavity) tested were in general multilongitudinal moded, the DAL crescent lasers (both 300 and 125 μm) were highly single-longitudinal moded for the entire current range tested (up to 3Ith), even under transient fast pulse excitation (high-bit rate modulation) and showed stability to mode hopping. DAL crescent lasers with short cavity (∼125 μm) operated stably in the same single-longitudinal mode under fast constant current pulse excitation at all time starting from the onset of optical pulse and approach the characteristics of distributed Bragg reflector lasers in spectral purity and stability.
High-pressure high-current transversely excited Sr+ recombination laser
Authors: Butler M. S. , Piper J. A.
Published: February 2003

Operation of a transversely excited Sr+ recombination laser at buffer gas (He) pressures up to 1300 Torr and discharge current densities up to 103 A/cm2 is reported. Specific energy densities on the λ430.5-nm Sr+ line exceed 50 μJ/cm3 for the 30-cm3 active volume device with no fundamental limitations observed. Double-pulse experiments indicate pulse repetition frequencies near 1 MHz may be possible.
High density optical disk with V-shaped grooves
Authors: Nagashima Michiyoshi
Published: February 2003

Properties of diffracted light back from an optical disk, which has grooves with a V-shaped cross-sectional configuration, are studied by employing scalar diffraction theory. The V-shaped grooves are spaced bottom to bottom by a presently used track pitch, and all walls of the grooves are capable of storing information. If the optical depth of the V-shaped groove is one-fourth of the wavelength of the laser, the 2nd or (−2)nd diffracted light beam contains only the information on a single wall. This property is utilized to double the information density of the optical disk.
Ion implanted grating couplers for optical waveguides
Authors: Kurmer J. P. , Tang C. L.
Published: February 2003

Fabrication of grating couplers by ion implantation for thin-film optical waveguides is reported. Ion implanted grating couplers were fabricated in both Corning 7059 glass waveguides and Ti-in-diffused LiNbO3 waveguides. Experimental coupling efficiencies on the order of a few percent were observed and agree reasonably well with expected theoretical values.
Spectral response of nearly degenerate four-wave mixing in photorefractive materials
Authors: Lam Juan F.
Published: February 2003

A theory of nearly degenerate four-wave mixing in photorefractive materials is presented. We predict the existence of self-oscillation, intensity-dependent bandwidth, and nonlinear phase shift effects. UFDAT;8342.65.Cq, 42.80.Ks
Luminescence measurements of laser induced recombination centers in (Al,Ga)As
Authors: Zysset B. , Salathé R. P. , Gilgen H. H.
Published: February 2003

The photoluminescence of laser created recombination centers in Al0.22 Ga0.78As has been investigated in the temperature range 30–550 K. A Gaussian type of emmision profile with a half-width varying from 33 meV at 30 K to 85 meV at 300 K has been found. Profile and variation of half-width can be described by a configuration-coordinate (CC) model. The laser generated centers exhibit significant differences compared to native or thermally induced defect centers: the half-width is much smaller, the peak energy shift with temperature is negative, and the activation energy for quenching is well above room temperature. These differences are explained in terms of the CC model by an unusually low vibration energy of the ground state and possibly by a temperature variation of the separation X0 ofthe potential energy minima of the ground and excited states of the center.
Lateral diffusion of arsenic in low pressure chemical vapor deposited polycrystalline silicon
Authors: Lewis N. , Gildenblat G. , Ghezzo M. , Katz W. , Smith G. A.
Published: February 2003

Electron microprobe analyses were performed on 75As-implanted polycrystalline silicon to determine the lateral diffusivity for annealing temperatures between 850 and 1100 °C. A value of 2.5×10−11 cm2/s for the effective lateral diffusion of As in the polycrystalline silicon was determined. Once the grains reached a constant size as a function of annealing time, no change in the value of the diffusion coefficient was noted.
Radiation effects on modulation-doped GaAs-AlxGa1−xAs heterostructures
Authors: Tsui D. C. , Gossard A. C. , Dolan G. J.
Published: February 2003

The effects of 35-KeV electron beam and 60Co gamma radiation on modulation-doped GaAs-AlxGa1−xAs heterostructures were studied by measuring the transport and the quantum transport of and the field effect on, the two-dimensional (2D) electrons in GaAs at the heterojunction interface. While the γ radiation in doses up to 1.3×106 rad causes no appreciable changes in the 2D transport properties, the electron beam irradiation reduces the electron mobility. This reduction in electron mobility is ∼50% for electron doses of 10−10 C/μm2.
Chemical stabilization of the coumarin 1 dye laser
Authors: von Trebra Robert J. , Koch Tad H.
Published: February 2003

The chemical stabilization of coumarin 1, 7-diethylamino-4-methylcoumarin, in a nitrogen laser pumped dye laser and coumarin 311, 7-dimethylamino-4-methylcoumarin, under cw conditions with sulfur-free radical chain transfer agents, are described. The mechanism for stabilization involves encounter of triplet coumarin and ground state coumarin with subsequent radical formation and radical disproportionation catalyzed by the chain transfer agents. The output of the coumarin 1 dye laser decreased 10% when the dye solution was stabilized with cysteine hydrochloride over a 12-h period. The output of the unstabilized dye laser decreased 50% during a similar period of operation.
Visible cw single quantum well (AlGa)As diode lasers
Authors: Lindström C. , Burnham R. D. , Scifres D. R.
Published: February 2003

In this letter we report on visible cw single quantum well (AlGa)As diode lasers grown by metalorganic chemical vapor deposition. The operating wavelength is 7210 Å. A linear output power up to 10 mW for a threshold current of 75 mA is achieved. The laser consists of a single quantum well double heterostructure with a 9-μm-wide proton implanted stripe. Double peaked far-field patterns, modulation bandwidths to 2.7 GHz, and a flat noise spectra with a reduced shot noise peak at 2 GHz are obtained.
Heat treatment of semi-insulating chromium-doped gallium arsenide substrates with converted surface removed prior to molecular beam expitaxial growth
Authors: Palmateer S. C. , Schaff W. J. , Galuska A. , Berry J. D. , Eastman L. F.
Published: February 2003

Silicon-doped gallium arsenide molecular beam epitaxy (MBE) layers were grown on chromium-doped semi-insulating GaAs (Bridgeman grown) heat-treated (converted surface removed before growth) or nonheat-treated substrates. Secondary ion mass spectrometric (SIMS) measurements show a marked reduction of outdiffused manganese in layers grown on heat-treated substrates with converted surface removed prior to MBE growth. Secondary ion mass spectrometric studies and capacitance voltage free-carrier profiling indicate a redistribution of Si in layers grown on nonheated substrates not observed in epilayers on heat-treated substrates (converted surface removed prior to MBE growth).
Nonuniform photoluminescence intensity distribution on semi-insulating GaAs and effects of Cr and dislocations
Authors: Kitahara K. , Ozeki M. , Shibatomi A.
Published: February 2003

The nonuniformity of semi-insulating GaAs is studied by the near-band-edge luminescence (PL) intensity profile along the diameter of circular wafers grown by the liquid encapsulated Czochralski technique. The shapes of the profiles depend on the location of the wafer in the ingots and on the density of Cr. Many sharp peaks are observed in the profiles of undoped and lightly Cr-doped ingots but are suppressed by heavy doping of Cr. PL intensity is enhanced in the region where dislocation density is high. This correlation is explained by the interaction between the dislocation and the nonradiative center.
20-GHz bandwidth GaAs photodiode
Authors: Wang S. Y. , Bloom D. M. , Collins D. M.
Published: February 2003

A high-speed GaAs Schottky barrier photodiode with 3-dB bandwidth of 20 GHz, an external quantum efficiency at 600 and 845 nm of ≥25%, and operating at less than 5-V reverse bias is reported. Accurate characterization of these devices in both the time and the frequency domains is discussed.
Surface acoustic wave memory correlator on semi-insulating GaAs
Authors: Melloch M. R. , Wagers R. S. , Williams R. E.
Published: February 2003

Experimental evaluation of a monolithic surface acoustic wave memory correlator fabricated on a semi-insulating GaAs wafer is reported. The correlator employed the piezoelectricity of the GaAs substrate alone without need for a ZnO overlay. A strip coupling technique was used to couple the acoustic region to the Schottky diode region which was defined by selective ion implantation. The device, with 40 wavelength long interdigital transducers, had a 3-dB bandwidth of 5 MHz. The 0.8-μs-long correlation region had 500 diodes uniformly spaced at a spatial frequency of 0.5 Rayleigh wavelengths at 300 MHz. With all ports untuned, the input-port transduction loss was 16.9 dB; an external correlation efficiency of −87 dBm was obtained.
Optogalvanic effects in the obstructed glow discharge
Authors: Doughty D. K. , Lawler J. E.
Published: February 2003

An anomalously strong 594.5-nm optogalvanic effect is observed in an obstructed glow discharge in 1.0 Torr of Ne occurring between plane parallel Al electrodes separated by 1.0 cm. The absolute size of a steady-state optogalvanic effect is characterized by a dimensionless ratio of the change in power delivered to the load resistor over the absorbed laser power. A ratio of −400 for the 594.5-nm effect is observed in the obstructed glow discharge, while ratios of −6 are typical for the 594.5-nm effect in the positive column discharge. The 594.5-nm effect in the obstructed glow discharge results from a laser induced depletion of metastable atoms which play an important role in electron emission from a cold cathode.