bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of thermal-wave imaging to other analysis methods
Authors: Marek Jiří , Strausser Yale E.
Published: February 2003

Thermal-wave microscopy is a recent innovation which is potentially very useful for characterizing defects in semiconductor materials. To help understand the mechanisms which generate contrast in thermal-wave micrographs we have done a correlation study with optical microscopy, backscattered electron imaging, electron beam induced current imaging, light beam induced current imaging, and x-ray topography. For this study we used a section of a polycrystalline silicon solar cell. The results show a strong correlation for both crystalline defects and for electrically active defects in this material but thermal-wave microscopy has the advantages of speed of analysis and lack of specimen preparation required.
Method for the simultaneous measurement of surface and bulk conductance in semiconductors
Authors: Migliorato P. , Parisi V.
Published: February 2003

A new method is proposed for the simultaneous measurement of bulk and surface conductances in semiconductors, based on the use of three surface contacts. Detailed numerical calculations of the electric field distribution in the sample are presented and the role of geometrical parameters (contact spacing, width, and sample thickness) is discussed. The method can find direct application in the assessment of processing-induced modifications in the surface and bulk of semiconductor materials.
Surface structures and properties of ZnSe grown on (100)GaAs by molecular beam epitaxy
Authors: Park R. M. , Salansky N. M.
Published: February 2003

Single crystal ZnSe films have been grown on (100) orientated GaAs by molecular beam epitaxy (MBE) from a single Knudsen oven containing ZnSe compound material. The ZnSe Knudsen oven temperatures required to provide reasonable growth rates (0.15–0.33 μm/h) are in the range 950–1000 °C. ZnSe films grown at substrate temperatures around 350 °C have extremely smooth surfaces, as indicated by both reflection high-energy electron diffraction and scanning electron microscope observations. We report for the first time the observation of (1×3) surface reconstruction on ZnSe grown by MBE at substrate temperatures ≥470 °C.
Nonreciprocal laser-microchemical processing: Spatial resolution limits and demonstration of 0.2-μm linewidths
Authors: Ehrlich D. J. , Tsao J. Y.
Published: February 2003

A simple model, which includes the important effects of ‘‘nonreciprocity’’ (nonlinear dependence on intensity), is developed to describe the spatial resolution of single-step focused-beam, microchemical fabrication techniques. Qualitative comparisons are made to patterning by double-step (resist) and by projected-image processes. At a given wavelength, linewidths are shown to be narrowest for microchemical processes. Linewidths <0.2 μm, i.e., narrower than the Rayleigh optical diffraction limit, are demonstrated for laser-activated deposition and doping of silicon at visible wavelengths.
Picosecond time response of a transverse electric atmospheric CO2 laser amplifier
Authors: Mukherjee P. , Kwok H. S.
Published: February 2003

The gain of an atmospheric pressure CO2 laser amplifier was measured as a function of the input pulse duration for the first time using optical free-induction decay pulses. It was found that the gain decreases rapidly for pulses shorter than 150 ps, in agreement with the gain bandwidth predictions.
Surface and interface acoustic waves in SiO2/Y
X-LiNbO3
Authors: Cullen D. , Meltz G. , Grudkowski T.
Published: February 2003

For Y-cut lithium niobate, a leaky shear horizontal (SH) surface wave is known to propagate along the X axis. When an SiO2 film is deposited on the LiNbO3 surface, the SH wave is found experimentally to have low loss and theoretical calculations show the wave to be closely confined to the surface. Two additional acoustic modes are observed in the SiO2/YX-LiNbO3 configuration. One mode is a Rayleigh-type surface wave and the other a generalized Stoneley wave. Experimental measurements and theoretical predictions of the wave velocities versus film thickness to wavelength ratio (h/λ) are presented. Measurements of the temperature coefficient of time delay are given for the SH wave showing a zero first order coefficient at h=0.42λ. The sensitivity of this wave to bending strains is also presented.
Low-energy high flux reactive ion etching by rf magnetron plasma
Authors: I Lin , Hinson D. C. , Class W. H. , Sandstrom R. L.
Published: February 2003

The magnetron plasma etching of SiO2 and Si in fluorocarbon gas has been investigated. The plasma has high ionization degree, collisionless high density, and low energy ion flux (I∼1.0 mA/cm2, 30≲Ei ≲250 eV at 1 W/cm2) and a controllable etch uniformity. The bulk of the plasma supports an electric field which can be shaped to achieve normal ion bombardment of the etching surface. Good etching anisotropy, high SiO2/Si selectivity, and rates six times greater than conventional reactive ion etching were demonstrated.
Early oxidation stage of copper during cw CO2 laser irradiation
Authors: Ursu I. , Nistor L. C. , Teodorescu V. S. , Mihăilescu I. N. , Nanu L. , Prokhorov A. M. , Chapliev N. I. , Konov V. I.
Published: February 2003

The early oxidation stage of copper under the action of cw CO2 laser radiation was investigated by transmission electron microscopy, selected area diffraction, and scanning electron microscopy, in correlation with target absorptivity determinations of l0.6-μm laser light by calorimetry. The results are discussed in connection with available theoretical interpretations.
Thin-film adhesion changes induced by electron irradiation
Authors: Mitchell I. V. , Williams J. S. , Smith P. , Elliman R. G.
Published: February 2003

The adhesion of thin films of gold, sputter deposited onto silicon, is shown to be improved by subsequent irradiation with 5–30-keV electrons. The similarities between electron and heavy ion irradiation effects suggest a common (electronic) origin for the change in interfacial bonding.
Deep level transient spectroscopy of defects introduced by resistive evaporation of metals on silicon
Authors: Auret F. D. , Kleinhenz R. , Schneider C. P.
Published: February 2003

Schottky barrier diodes were formed on n- and p-type silicon by resistive evaporation of Ti and Au. The defects introduced in the substrate near the metal-silicon interface were characterized by deep level transient spectroscopy. For n-type devices defects were observed at 0.11, 0.14, and 0.17 eV below the conduction band, while for p-type devices one defect at 0.33 eV above the valence band was measured. All these defects could be removed by annealing the devices at 175 °C for 10 min.
Properties of amorphous silicon tin alloys produced using the radio frequency glow discharge technique
Authors: Mahan A. H. , Williamson D. L. , Madan A.
Published: February 2003

Amorphous silicon tin films have been deposited by the glow discharge technique using SiH4, H2, and SnCl4 or Sn (CH3)4 gas mixtures. An n to p-type conductivity transition with increasing Sn content in the films is found for both types of Sn alloying sources. Such a transition satisfactorily explains the observed dark and light conductivity behavior.
Air-bridge microbolometer for far-infrared detection
Authors: Neikirk Dean P. , Rutledge David B.
Published: February 2003

A new microbolometer for far-infrared detection has been fabricated that allows an increase in sensitivity of a factor of 4 over the best previously reported bolometer. By suspending the detector in the air above its substrate a reduction in the thermal conductance out of the device by a factor of 5 has been achieved. At a modulation frequency of 100 kHz this microbolometer has an electrical noise equivalent power of 2.8×10−11 W(Hz)−1/2. A thermal model is also presented that accurately fits the response of the detector.
Longitudinal-mode control in integrated semiconductor laser phased arrays by phase velocity matching
Authors: Kapon E. , Katz J. , Margalit S. , Yariv A.
Published: February 2003

The spectrum of semiconductor laser arrays with separate contacts is investigated. It is demonstrated that the individual laser currents can be selected such that the array operates in a single longitudinal mode in contrast to the multimode nature of its individual constituents. Moreover, it is possible to tune the lasing frequency by varying the laser currents. Wavelength tuning range of ∼50 Å, with tuning rate of ∼5 Å/mA, is demonstrated. It is suggested that these spectral features, characteristic of lasers which are coupled in parallel, result from the strong frequency dependence of their spatial mode pattern near the phase-matching frequency of their coupled waveguides.
Cross-talk problems in optical directional couplers
Authors: Chen Kuo-Liang , Wang Shyh
Published: February 2003

Cross-talk in optical directional couplers is usually considered to be limited only by the processing technology. We show that unequal coupling of an input wave to the even and the odd mode of the coupling region gives rise to another kind of cross-talk. The extinction ratio is well approximated by the overlap integral of the fields in the two waveguides. For a given coupling length, the higher the index step a waveguide has, the less the cross-talk is. For straight couplers without bends one way to eliminate the cross-talk is to offset the input wave relative to the coupled guides with the penalty of power loss. A three-waveguide coupler has a different cross-talk problem of comparable magnitude.
Direct heterodyne detection of 245-GHz radiation using the internal narrowband oscillations of a resistive dc SQUID
Authors: Verschueren J. M. V. , Uiterwaal A. A. , van der Heijden R. W. , Wyder P.
Published: February 2003

A current controlled voltage across a resistive section in a double Josephson junction interferometer (dc resistive superconducting quantum interference device) maintains a difference voltage between the junctions to generate a narrowband oscillatory signal at the beat frequency νq of the individual junction frequencies. This internal oscillation was used to directly down-convert a signal at 246 GHz to a very low (<1 MHz) intermediate frequency.
Direct energy gap of Al1−xInxAs lattice matched to InP
Authors: Wakefield B. , Halliwell M. A. G. , Kerr T. , Andrews D. A. , Davies G. J. , Wood D. R.
Published: February 2003

The direct energy gap of thin, undoped epitaxial layers of Al1−xInxAs grown on (100) InP has been measured as a function of In content for values of x between 0.46 and 0.55 using catholuminescence spectroscopy. For the composition lattice matched to InP it was measured to be 1.450 eV at room temperature, and 1.508 eV at 4 K. Over the limited range of compositions studied, it varied as Eg =1.450+2.29 Δx eV at room temperature, and as Eg =1.508+2.22 Δx eV at 4 K, where Δx=(0.52−x), the deviation of x from the lattice-matched value.
Negative ion densities in NF3 discharges
Authors: Greenberg K. E. , Hebner G. A. , Verdeyen J. T.
Published: February 2003

This letter shows that the negative ion density in the NF3 discharge is one to two orders of magnitude larger than the electron density. A XeCl laser was used to photodetach the ions and the resultant excess electron population was measured using microwave interferometry.
Subbands and charge control in a two-dimensional electron gas field-effect transistor
Authors: Vinter B.
Published: February 2003

A calculation of the subband structure and charge distribution in an AlxGa1−xAs/GaAs heterojunction as a function of gate voltage at room temperature has been performed. The results show that usually about 80% of the electrons in the channel are in the lowest two subbands and describe for the first time quantitatively the transition from the simple capacitive charge control regime to the regime where the channel density is no longer controlled by the gate voltage.
Millimeter wave emission from a rotating electron ring in a rippled magnetic field
Authors: Bekefi G. , Shefer R. E. , Destler W. W.
Published: February 2003

We report measurements of millimeter wave emission from a rotating relativistic electron ring (2 MV, 1 kA) in which electrons move in quasi-circular orbits under the combined action of a uniform axial magnetic field and an azimuthally periodic wiggler magnetic field. We observe radiation at frequencies above 91 GHz, at power levels in excess of 200 kW.
Picosecond time-resolved reflectivity and transmission at 1.9 and 2.8 μm of laser-generated plasmas in silicon and germanium
Authors: van Driel H. M. , Lompré L.-A. , Bloembergen N.
Published: February 2003

We have observed plasmon resonances with 1.9-μm and 2.8-μm probe pulses in silicon and germanium, excited by 25-ps pulses up to 40 mJ/cm2 at 0.53 and 1.06 μm, respectively. Firm values of N/m* are derived.
Solid phase epitaxy of silicon on gallium phosphide
Authors: de Jong T. , Saris F. W. , Tamminga Y. , Haisma J.
Published: February 2003

Epitaxial silicon films have been grown on gallium phosphide by molecular beam and solid phase epitaxy or combinations of both methods. During molecular beam epitaxial growth Ga segregates on top of the Si films, which can be considerably reduced by solid phase epitaxy but not completely suppressed. The cause of segregation is investigated using Rutherford backscattering, defect etching, and scanning electron microscopic inspection. We conclude that imperfections in the epitaxial layer act as diffusion pipes for atoms.
Sensitive reflection high-energy electron diffraction measurement of the local misorientation of vicinal GaAs surfaces
Authors: Pukite P. R. , Van Hove J. M. , Cohen P. I.
Published: February 2003

Reflection high-energy electron diffraction (RHEED) is used to determine the local misorientation of vicinal, molecular beam epitaxy prepared GaAs surfaces. With the glancing angle of incidence fixed, the intensity along the (00) streak is measured for different crystal azimuths. The specular beam is observed to split by an amount that depends upon the scattering geometry and surface misorientation. The method is applied to surfaces misoriented with respect to low-index bulk planes by an average polar angle of 2°, 1°, and 5 mrad. Local polar and azimuthal misorientations were determined to within 5% and 10°, respectively. The measurement shows that an important mechanism responsible for RHEED streaks is diffraction from ordered staircase steps.
Inhibition of acid etching of Pt by pre-exposure to oxygen plasma
Authors: Kim M. J. , Gruenke L. A. , Saia R. J. , Cohen S. S.
Published: February 2003

Platinum etching characteristics in aqua regia have been studied. It was found that prior exposure to an oxygen plasma inhibits the dissolution of platinum in aqua regia. Oxygen, far more abundant in the exposed platinum than in the unexposed platinum, plays a key role in forming an inhibition layer, such as PtO2, which prevents chlorine ion attack. This inhibition layer appears to retard platinum etching effectively in chlorine-based etch solutions. The layer has been observed to form at a fast rate, and it is insensitive to the oxygen partial pressure in the plasma chamber. The insoluble characteristics of both the inhibited platinum and the platinum silicide in aqua regia make it feasible to form an unframed contact interconnection for applications of very large scale integration.
High resolution electron beam lithography on CaF2
Authors: Mankiewich P. M. , Craighead H. G. , Harrison T. R. , Dayem A. H.
Published: February 2003

We have fabricated 30-nm lines on 200-nm centers in CaF2 using a scanning transmission electron microscope. The lines were written by electron beam radiolysis of a fine grain polycrystalline CaF2 film and reaction to CaO followed by development in H2O.
Use of a diode laser to observe room-temperature, low-power optical bistability in a GaAs-AlGaAs etalon
Authors: Tarng S. S. , Gibbs H. M. , Jewell J. L. , Peyghambarian N. , Gossard A. C. , Venkatesan T. , Wiegmann W.
Published: February 2003

Optical bistability is observed using a single-mode diode laser in a GaAs-AlGaAs multiple-quantum-well etalon with as low as six mW power at 830 nm.
Spectral bistability in coupled cavity semiconductor lasers
Authors: Olsson N. A. , Tsang W. T. , Logan R. A. , Kaminow I. P. , Ko J-S.
Published: February 2003

Bistability in the spectral output of a two-section cleaved-coupled-cavity (C3) semiconductor laser is observed. A wide (10 mA) and temperature insensitive hysteresis loop is obtained at laser currents up to at least 3×Ith and the laser can be switched with subnanosecond electrical pulses between its two spectraly pure states. The switching is characterized by a power-delay product of 4×10−12 J and a switching time of less than 1 ns.
Transverse acceleration of electrons using laser or maser drivers
Authors: Schoen Neil C.
Published: February 2003

The utilization of coherent traveling electromagnetic waves to accelerate charged particles has been investigated. In the visible frequency region, electrons can be accelerated to energies in the range of 0.1 GeV within distances of 100 μm for electric fields of 6×1013 V/m. The Rayleigh region of a near diffraction limited laser beam provides the high power densities and proper ‘‘turn-off’’ to accelerate electrons. The use of masers as drivers for this process is also shown to produce comparable levels of acceleration.
Phase relations in the Cu, In, Se system and the properties of CuInSe2 single crystals
Authors: Bachmann K. J. , Fearheiley M. , Shing Y. H. , Tran N.
Published: February 2003

Experimental data on the phase relations in the Cu, In, Se system are presented and the growth of single crystals of CuInSe2 from the melt is described. Hall measurements on both n- and p-type crystals reveal that impurity conduction dominates the low-temperature transport properties. Type conversion by annealing of initially n-type crystals in excess selenium vapor leads to a substantial increase in the compensation level.
Bias effects on the deposition of hydrogenated amorphous silicon film in a glow discharge
Authors: Ando K. , Aozasa M. , Pyon R. G.
Published: February 2003

Bias effects on the deposition of hydrogenated amorphous silicon (a-Si:H) film in the glow discharge were investigated by triode system which can control the negative bias without changing the other deposition conditions. The growth rate, H content, and photoconductivity of the film deposited at the substrate temperature 300–320 °C increased with the negatively enhanced bias. The results would be due to the enhancement of  ion flow by the bias and show that the bias has an advantage for the improvement of the a-Si:H film characteristics.
Hydrogen diffusion along passivated grain boundaries in silicon ribbon
Authors: Dubé C. , Hanoka J. I. , Sandstrom D. B.
Published: February 2003

Using the electron beam induced current mode of the scanning electron microscope, a technique has been developed to study the extent of hydrogen passivation and diffusion along grain boundaries in silicon ribbon grown by the edge-defined film-fed growth process. Passivation and diffusion depths x, ranging from a few microns to more than 200 microns have been found. Grain boundary diffusivities of 10−8–10−9 cm2/s have been measured. A finite width to the spatial distribution of recombination centers along the grain boundaries has been found and measurements of the surface recombination velocity S, indicate that, for S≥2×104 cm/s, ln S∝x.
Organometallic vapor phase epitaxial growth of high purity GaInAs using trimethylindium
Authors: Kuo C. P. , Yuan J. S. , Cohen R. M. , Dunn J. , Stringfellow G. B.
Published: February 2003

Gax In1−xAs lattice matched to the InP substrate (x=0.47) has been grown by organometallic vapor phase epitaxy using trimethylindium (TMIn) and trimethylgallium (TMGa) as the group III sources and AsH3 as the As source. In a simple, horizontal, atmospheric pressure reactor, the GaInAs growth proceeds without visible evidence of parasitic prereaction problems. The process yields homogeneous, reproducible GaInAs with a high growth efficiency and a solid/vapor In distribution coefficient of nearly unity. Most importantly, several layers with room-temperature electron mobilities of approximately 10 000 cm2/Vs and carrier concentrations of approximately 1015 cm−3 have been produced. The 4-K photoluminescence shows a narrow (4–5 meV) band-edge emission peak and a low-intensity band acceptor peak at ∼18 meV lower energy. Surface morphologies are routinely featureless as observed by high magnification interference contrast microscopy.
Single photon detection at 1.3 μm using a gated avalanche photodiode
Authors: Levine B. F. , Bethea C. G.
Published: February 2003

We have done experiments on the detection of single photons at a wavelength of 1.3 μm using a gated Ge avalanche photodiode pulse biased above breakdown. The influence of traps on the breakdown voltage was measured and the possibility of using such an ultrasensitive photodiode as a quantum limited detector for optical communications is discussed.
Josephson properties of Nb3Ge/oxide/Pb tunnel junctions
Authors: Tanabe K. , Asano H. , Michikami O.
Published: February 2003

Nb3Ge/oxide/Pb Josephson tunnel junctions have been fabricated on magnetron-sputtered Nb3Ge thin films using standard photolithography and a CF4 plasma cleaning technique. Their Josephson properties have also been investigated. High-quality junctions with a well-defined large gap (∼5 mV) and low excess conductance (Vm=35 mV) can be obtained by adopting large-grained high-Tc films. These junctions are found to have an Nb3Ge magnetic penetration depth of less than 200 nm, and a specific capacitance a little lower than that for Nb/Nb oxide/Pb junctions.
High current density photoemissive electron source
Authors: Lee Chunghsin
Published: February 2003

A high current, high current density cesium antimonide photoemissive electron source was constructed and tested over an extended period of time with small degradation. A photocurrent density of more than 3 A/cm2 was obtained with a performance drop of about 15% over a 70-h period. The slow decay was caused by cesium desorption from the cathode. Cesium evaporated onto the surface at the end of the test rejuvenated the photocathode to its original response. Such a photoemissive source has particular applications to electron beam lithography machines and high resolution, nondestructive electron microscopes.
Dopant profiling in silicon on sapphire using spreading resistance
Authors: Pawlik M. , Groves R. D.
Published: February 2003

Results are presented of accurate dopant (boron and phosphorus) profiles in silicon on sapphire and comparable profiles in bulk silicon. These profiles have been determined by spreading resistance. It is shown that a well controlled spreading resistance facility has the required sensitivity, depth resolution, and dynamic range for profiling electrically active dopants in thin silicon on sapphire films.
Microwave integrated optical modulator
Authors: Cross Peter S. , Baumgartner Richard A. , Kolner Brian H.
Published: February 2003

A Ti-diffused lithium niobate, traveling wave modulator has been fabricated and tested at microwave frequencies. A Mach–Zehnder interferometer optical configuration and a coplanar waveguide electrical transmission line are used. For a 4-mm interaction length, the modulator has a 3-dB bandwidth of 13 GHz and requires only 2 V to switch at λ=840 nm. The frequency response is measured directly using an ultrahigh speed photodiode, and the test setup therefore constitutes the highest bandwidth efficient electro-optical transmission system ever reported.
Consequences of a lower level population on the modeling of a homogeneously broadened injection laser
Authors: Cassidy Daniel T.
Published: February 2003

An exact, analytic solution has been found for the coupled, nonlinear differential equations which describe the amplification of mode intensities for propagation through a homogeneously broadened amplifier with negligible population in the lower level. It is shown in this letter that the predictions of an analytic laser model based on the solutions to these equations can be scaled in a straight forward and easy manner to include the effects of a constant, lower level population.
High-quality single GaAs quantum wells grown by metalorganic chemical vapor deposition
Authors: Miller R. C. , Dupuis R. D. , Petroff P. M.
Published: February 2003

GaAs-AlxGa1−xAs single and multiquantum well structures grown by metalorganic chemical vapor deposition have been examined for the first time in detail using low-temperature photoluminescence, cathodoluminescence, and transmission electron microscopy. The better heterointerfaces are very uniform with a large scale roughness of approximately plus or minus a monolayer along the interface on a scale of the exciton diameter or larger and a composition gradient width of less than three monolayers across the interface. The GaAs well interface roughness and associated impurity luminescence are not very sensitive to the thickness of the AlxGa1−xAs prelayer. With nonoptimum growth conditions, the quantum well photoluminescence characteristics suggest a substantial amount of band filling due to holes presumably from the AlxGa1−xAs layers.
Stability of NiSi2 and CoSi2 in contact with their free metal
Authors: Cahoon E. C. , Comrie C. M. , Pretorius R.
Published: February 2003

Rutherford backscattering has been used to study metal/disilicide thin-film interactions for Ni and Co. Upon heating, the metal reacted with disilicide to produce the phase M2Si in both cases. On further heating the M2Si itself reacted with the disilicide to form MSi. In the case of Co it was found that after all the metal had been converted to CoSi in this way, the reaction stopped. However, with Ni the disilicide substrate continued to dissociate into NiSi and Si even after all the original Ni had reacted to form NiSi. The stability of NiSi2 under various conditions was investigated and it appears that twin requirements of a crystalline silicon substrate on which the excess Si can regrow and nucleation sites in the form of NiSi are necessary in order to induce dissociation.
Infrared spectrum of interstitial oxygen in silicon
Authors: Stavola Michael
Published: February 2003

A stress-induced dichroism study of the 1106-cm−1 and 515-cm−1 modes of interstitial oxygen in silicon has been undertaken in order to assign the 515-cm−1 mode. It has been found that the 515-cm−1 mode is due to the symmetric stretching motion of the Si–O–Si ‘‘defect molecule’’ that has often been used to explain the vibrational spectrum of interstitial oxygen. The implications of the assignment to both the structure of the oxygen interstitial and to the characterization of oxygen concentration are discussed.
Polarization hysteresis in dielectric films using light diffraction by acoustic waves
Authors: Attard Alfred E. , Kuehls John F.
Published: February 2003

A new method for determining polarization hysteresis in dielectric films is described. The technique is capable of determining the type of polarization as well as the relaxation time. Results are described for Mylar.
Schottky barrier restricted arrays of phase-coupled AlGaAs quantum well lasers
Authors: Temkin H. , Dupuis R. D. , Logan R. A. , van der Ziel J. P.
Published: February 2003

Simple, self-aligned phase-coupled laser arrays consisting of ten 3-μm-wide stripes are described. The current flow was confined to the stripes by a Schottky barrier over the remainder of the laser chip. This process, applied to the AlGaAs graded-index structures grown by metalorganic vapor phase epitaxy, produced arrays with threshold currents as low as 20 mA/stripe. The devices are capable of output powers of up to 1 W/facet and operate at temperatures as high as 100 °C with a stable far-field pattern. In addition, novel information on the phase coupling in these gain-guided arrays has been obtained.
Coupled parallel waveguide semiconductor laser
Authors: Mukai S. , Kapon E. , Katz J. , Lindsey C. , Rav-Noy Z. , Margalit S. , Yariv A.
Published: February 2003

The operation of a new type of tunable laser, where the two separately controlled individual lasers are placed vertically in parallel, has been demonstrated. One of the cavities (‘‘control’’ cavity) is operated below threshold and assists the longitudinal mode selection and tuning of the other laser. With a minor modification, the same device can operate as an independent two-wavelength laser source.
Determination of carrier collection length and prediction of fill factor in amorphous silicon solar cells
Authors: Faughnan Brian W. , Crandall Richard S.
Published: February 2003

Using a carrier collection length lc, defined for penetrating light, a convenient technique for measuring lc, in pin cells is demonstrated. We show experimentally that lc, predicts the fill factor measured with white light under AM1 conditions for a wide variety of pin cells. A simple model is presented which fits the experimental results. The implications of these results on the carrier collection loss for strongly absorbed light are discussed.
7.2% efficient polycrystalline silicon photoelectrode
Authors: Cogan George W. , Gronet Chris M. , Gibbons James F. , Lewis Nathan S.
Published: February 2003

After etching, n-type cast polycrystalline silicon photoanodes immersed in a solution of methanol and a substituted ferrocene reagent exhibit photoelectrode efficiencies of 7.2%±0.7% under simulated AM2 illumination. Scanning laser spot data indicate that the grain boundaries are active; however, the semiconductor/liquid contact does not display the severe shunting effects which are observed at a polycrystalline Si/Pt Schottky barrier. Evidence for an interfacial oxide on the operating polycrystalline Si photoanode is presented. Some losses in short circuit current can be ascribed to bulk semiconductor properties; however, despite these losses, photoanodes fabricated from polycrystalline substrates exhibit efficiencies comparable to those of single crystal material. Two major conclusions of our studies are that improved photoelectrode behavior in the polycrystalline silicon/methanol system will primarily result from changes in bulk electrode properties and from grain boundary passivation, and that Fermi level pinning by surface states does not prevent the design of efficient silicon-based liquid junctions.
Silicon nitride films deposited with an electron beam created plasma
Authors: Bishop D. C. , Emery K. A. , Rocca J. J. , Thompson L. R. , Zarnani H. , Collins G. J.
Published: February 2003

Silicon nitride films have been deposited using an electron beam created plasma in a silane, ammonia, and nitrogen mixture. The films were deposited at substrate temperatures between 50 and 400 °C. Physical, chemical, and electrical properties of these films are reported.
High-rate deposition of amorphous hydrogenated silicon from a SiH4 plasma
Authors: Hamasaki T. , Ueda M. , Chayahara A. , Hirose M. , Osaka Y.
Published: February 2003

An extremely high deposition rate of amorphous hydrogenated silicon has been achieved by employing a new rf discharge technique. The deposition rate has been increased to more than 50 Å/s at a substrate temperature of 200 °C without accompanying any appreciable deterioration in the electronic and structural properties as compared to those of specimens prepared at a conventional deposition rate (∼1 Å/s). Thermal stability of the high-rate samples is improved with respect to that of low-rate specimens.
Passive Ti:LiNbO3 channel waveguide TE-TM mode splitter
Authors: Yap D. , Johnson L. M. , Pratt G. W.
Published: February 2003

A passive compact TE-TM mode splitter has been demonstrated using Ti:LiNbO3 channel waveguides. Its operation is based on the interference between the two guided modes of a double-mode waveguide segment connecting single-mode input and output guides. A device made using one set of design parameters has splitting ratios of 12 dB for both polarizations. Another device made using different parameters has a splitting ratio of 17 dB for TM modes. The devices are capable of low-loss, broadband operation.
Bulk acceptor compensation produced in p-type silicon at near-ambient temperatures by a H2O plasma
Authors: Hansen W. L. , Pearton S. J. , Haller E. E.
Published: February 2003

We report the neutralization of the shallow acceptors boron and gallium in p-type silicon to a depth >1 μm after exposure to a H2O plasma for 3 h at temperatures as low as 80 °C. The fact that uncompensated n-type silicon is unaffected by the plasma treatment means that donor formation is excluded. Exposure to either O2 or H2 plasmas does not lead to acceptor removal; however, sequential treatment in an O2 plasma followed by a H2 plasma produces the same effect as the H2O plasma while the inverse sequence has no effect. Our observations can be explained with a model considering rapidly diffusing atomic oxygen and hydrogen which recombine on acceptor sites forming neutral A−OH+ complexes. The model shows that acceptor compensation kinetics is dominated by the diffusion of atomic hydrogen.
High conversion efficiency and high radiation resistance InP homojunction solar cells
Authors: Yamamoto Akio , Yamaguchi Masafumi , Uemura Chikao
Published: February 2003

InP homojunction solar cells have been fabricated using thermal diffusion of sulphur or selenium into p-type InP substrates. A conversion efficiency of 16.5% (active area) was obtained for a S-diffused cell under simulated AM1.5 illumination. The InP solar cell was found for the first time to have a higher resistance to γ-ray radiation degradation than Si and GaAs solar cells with comparable junction depth. These results show a possibility of the InP solar cells for space applications.
Relationship between collection length and diffusion length in amorphous silicon
Authors: Faughnan Brian , Moore Arnold , Crandall Richard
Published: February 2003

We demonstrate a relationship between the diffusion length lD, as measured by the surface photovoltage (SPV) method and the collection length lco, measured on the same thin films of a-Si:H. lco is the appropriate quantity to describe current collection in p-i-n cells of a-Si:H, which is normally electric-field dominated. We have shown previously that lco can be used to predict the fill factor of p-i-n cells. Therefore, this letter justifies the use of lD measurements by SPV for optimizing the quality of i layers for p-i-n cells. An expression for ambipolar diffusion is presented and the experimental results are used to place limits on the relative magnitudes of electron and hole mobilities and lifetimes.
Excitation and Fe concentration dependences in the impulse photoconductance of InP:Fe
Authors: Hammond R. B. , Paulter N. G. , Wagner R. S. , Springer T. E.
Published: February 2003

We report impulse response measurements on InP:Fe photoconductors excited by laser and electron beam radiation. Measurements are reported on crystals with Fe concentrations from 2×1015 cm−3 to 4×1016 cm−3 and with excited electron-hole-pair densities of ∼1012 cm−3 and 9×1017 cm−3. Measured signal decays are purely exponential in character, and decay times are inversely related to Fe concentration. No long-lived tails are observed. Decay times show no dependence on excitation level for excited carrier concentrations that are well above and well below the Fe concentrations. The magnitude of the photoresponse indicates that electrons and not holes are the primary current carriers. The data suggest that for impulse excitation photoconductance decay in InP:Fe is due to trap-assisted recombination of electrons and holes at the Fe sites, with a rate determined by the species with the slower capture rate.
High resolution transmission electron microscopy study of Se+-implanted and annealed GaAs: Mechanisms of amorphization and recrystallization
Authors: Sadana D. K. , Sands T. , Washburn J.
Published: February 2003

High resolution transmission electron microscopy (HRTEM) has been applied to the study of amorphization and recrystallization mechanisms in Se+-implanted (100) GaAs. Selenium dose of 1×1014 cm−2 at 450 keV (projected range 1550 Å) produced an amorphous band in the depth range 250–2150 Å below the surface. Annealing at 400 °C resulted in the epitaxial regrowth of the upper and lower transition region (0–250 Å and 2150–2500 Å, respectively). Regrowth of the amorphous layer was found to proceed by the nucleation and propagation of the dense network of stacking fault bundles. Amorphization and recrystallization mechanisms in Se+-implanted GaAs are discussed in light of these HRTEM results.
Pair breaking critical current in a percolating superconductor
Authors: Alterovitz Samuel A. , Duby Thomas
Published: February 2003

The critical current of the percolating superconductor In-Ge was measured as function of temperature and metal concentration near the percolation threshold Xc. For samples with In concentration of 2 vol. % or more above Xc, we find a (1−t2)3/2 temperature dependence (t=T/Tc), corresponding to pair breaking current. Percolation theory results were found to apply for In-Ge. Using these results, we show that also the absolute value of the current is given by pair breaking theoretical calculations. For samples nearer to Xc, a weak link type behavior was observed.
Error rate measurement for single photon detection at 1.3 μm
Authors: Levine B. F. , Bethea C. G.
Published: February 2003

We have performed single photon detection experiments at 1.3 μm and measured the error rate re. This quantity is relevant for the possible use of such a detector as a quantum limited lightwave receiver. We have also determined the dependence of re on the quantum efficiency η.
Ultranarrow linewidth, magnetically switched, long pulse, xenon chloride laser
Authors: Pacala Thomas J. , McDermid I. Stuart , Laudenslager James B.
Published: February 2003

A spectral linewidth of <7×10−4 A and diffraction-limited beam divergence has been obtained from a long pulse, electric discharge xenon chloride laser with intracavity Fabry–Perot etalons. A gain duration of 100 ns provided for multipass operation of the etalons, significantly improving both contrast and finesse. The electrical discharge circuit required to produce this long gain duration was comprised of a pulse forming network, saturable inductor magnetic switch, and a tapered, constant impedance, interface transmission line.
Structure of reactively magnetron sputtered Hf-N films
Authors: Johansson B. O. , Sundgren J.-E. , Helmersson U. , Hibbs M. K.
Published: February 2003

In spite of the technical interest in the Hf-N system the form of the phase diagram is not yet clear, and therefore it is difficult to predict the phase composition of thin films. In this letter Hf-N films have been prepared by reactive dc planar magnetron sputtering and the phase composition of the films investigated by x-ray diffraction. Between the α-Hf and HfN single phase regions a multiphase region was found consisting of α-Hf, ε-Hf3N2, and/or ζ-Hf4N3 and also HfN in the nitrogen rich part. For the mononitride a lattice parameter of 4.54 Å was found which is slightly higher than reported bulk vlaues. This deviation is caused by intrinsic stresses in the films. If the nitrogen content is increased above that of the mononitride, the (111) interplanar distance increases further while all other interplanar distances decrease. At still higher nitrogen contents new reflections start to appear indicating a new phase. In this region the films also change from being conducting and nontransparent to electrically insulating and transparent.
Organometallic vapor phase epitaxial growth of GaAs0.5Sb0.5
Authors: Cherng M. J. , Stringfellow G. G. , Cohen R. M.
Published: February 2003

The pseudobinary III/V system GaAs1−ySby is well known to have a solid phase miscibility gap with a critical temperature of 751 °C. We have succeeded in growing epitaxial layers of GaAs0.5Sb0.5 lattice matched to InP at temperatures of 600 and 630 °C using the organometallic vapor phase epitaxy technique. The key requirement is a III/V ratio of greater than unity. This leads to the incorporation of all As and Sb reaching the interface and the ability to grow metastable alloys. The epitaxial GaAs0.5Sb0.5 layers have excellent surface morphology and efficient photoluminescence at a wavelength of 1.6  μm.
Electron-beam-induced information storage in hydrogenated amorphous silicon devices
Authors: Yacobi B. G.
Published: February 2003

A new method of recording and storing information in hydrogenated amorphous silicon devices is demonstrated. The storage mechanism is based on the formation of electron-beam-induced defects that act as recombination centers. In the charge collection mode of a scanning probe instrument (e.g., a scanning electron microscope), areas that experience bombardment appear darker in comparison to the unbombarded regions of the device. This leads to a contrast formation for pattern recognition. Annealing of the device at about 200 °C ‘‘erases’’ the stored information.
Surface treatment of (11̄02) sapphire and (100) silicon for molecular beam epitaxial growth
Authors: Christou A. , Richmond E. D. , Wilkins B. R. , Knudson A. R.
Published: February 2003

A low-temperature surface preparation technique for molecular beam epitaxial growth of silicon on sapphire and silicon is described. Thermal desorption of regrown oxide has been accomplished at 850 °C and epitaxial growth at 650 °C. A comparison of two surface treatment techniques for silicon (100) and sapphire (11̄02) substrates is reported.
Molecular beam epitaxy of Cd1−xMnxTe
Authors: Kolodziejski L. A. , Sakamoto T. , Gunshor R. L. , Datta S.
Published: February 2003

In this letter we report the first growth of high-quality, single crystal thin films of Cd1−xMnxTe; the films are deposited by molecular beam epitaxy. Cd1−xMnxTe is one of a newly developed class of magneto-optic materials called diluted magnetic semiconductors. Films with mole fractions of up to 50% Mn have been grown with no indication of any MnTe phases. A sputtered Auger electron spectroscopy depth profile shows that the Mn is uniformly incorporated throughout the film.
Supersaturation of self-interstitials and undersaturation of vacancies during phosphorus diffusion in silicon
Authors: Fahey P. , Dutton R. W. , Hu S. M.
Published: February 2003

A series of experiments were performed to settle the long-standing controversy on whether there is a vacancy excess or deficit during the diffusion of phosphorus in silicon. Phosphorus and antimony buried layers sandwiched between p-type substrates and p-type epitaxial layers were used to monitor the departure from equilibrium of point defects. It was found that diffusion of the antimony buried layer is retarded during high concentration phosphorus diffusion while diffusion of the phosphorus buried layer is enhanced. This finding is consistent with the hypothesis that there is simultaneously a vacancy undersaturation and a self-interstitial supersaturation. Possible causes of the interstitial supersaturation are investigated. It is concluded that the process whereby a phosphorus interstitialcy converts to substitutional form by emitting a self-interstitial is a likely source.
Low jitter streak camera triggered by subpicosecond laser pulses
Authors: Yen R. , Downey P. M. , Shank C. V. , Auston D. H.
Published: February 2003

We demonstrate the operation of an optically synchronized streak camera operating at 10-Hz repetition rate and has a system jitter of less than 2 ps. Synchronization is achieved with an iron-doped indium phosphide photoconductive switch which allows for room-temperature dc biasing. Femtosecond laser pulses are used for measuring the time response of the streak camera.
Field controlled charge trapping in tunnel oxides
Authors: Nagai Kiyoko , Hayashi Yutaka
Published: February 2003

The formation of oxide traps and interface traps in 3.5-nm oxides has been investigated using a metal-oxide-silicon capacitor subjected to forward bias stress. Negative charged traps causing current reduction were created by injecting electrons from a gate electrode in an oxide field greater than 3.7 MV/cm. Increase of current and negative shift in the capacitance-voltage curve, which indicated the formation of positively charged traps and interface traps, was observed for oxide fields greater than 5.4 MV/cm.
Superconducting critical current density of bronze processed pure and alloyed Nb3Sn at very high magnetic fields (up to 24 T)
Authors: Suenaga M. , Tsuchiya K. , Higuchi N.
Published: February 2003

Superconducting critical current densities Jc of pure and alloyed Nb3Sn layers of bronze processed monofilamentary wires were measured at 1.8 and 4.2 K in magnetic fields up to 24 T. The maximum in Jc at 20 T was found for Nb3Sn layers which were fabricated using (Nb ∼3.3 at. % Ti) cores, and the values of Jc were ∼670 and ∼370 A/mm2 at 1.8 and 4.2 K, respectively. These values are ∼5 and ∼25 times greater than those for ‘‘pure’’ Nb3Sn wires at these same temperatures. The functional dependence of Jc on the Ti content was also identical to that for the measured values of Hc2 vs Ti content for these wires. The maximum value of Hc2 of the wires with the matrix in place was 26.3 T for the wire which was fabricated from the core containing 3.3 at. % Ti in Nb.
Surface versus bulk magnetization curves in amorphous GdCo cosputtered in the presence of oxygen
Authors: Siegmann H. C. , Kay E.
Published: February 2003

Threshold photoemission and measurement of photoelectron spin polarization are used to investigate surface magnetism while avoiding radiation induced damage. By combining this technique with the measurement of longitudinal Kerr rotation, we show that the magnetic properties of these GdCo films are dominated by metallic Co in a Gd-oxide matrix quite in contrast to findings reported by Togami and Kobayashi [Jpn. J. Appl. Phys. 20, 1457 (1981)]. Mild annealing leaves bulk magnetic properties unchanged but produces dramatic magnetic changes in the surface.
Two-frequency addressing of a cholesteric texture change electro-optical effect
Authors: Gerber Paul R.
Published: February 2003

The Grandjean to focal conic texture change of cholesteric substances is examined by utilizing a two-frequency addressable cholesteric material. Conditions for multiplexed addressing of this brilliant electro-optical effect are studied. The storage property makes it suitable for application in displays of high information content. However, relatively high driving voltages, temperature sensitivity of driving conditions, and relatively slow response indicate possible indoor applications in displaying slowly changing information.
Effect of external optical feedback on the spectral properties of cleaved-coupled-cavity semiconductor lasers
Authors: Olsson N. A. , Dutta N. K.
Published: February 2003

The effects of external optical feedback on the spectral properties of cleaved-coupled-cavity (C3) single mode lasers have been investigated. cw mode rejection ratios and intensity dropout rates have been measured at different optical feedback strengths. The study shows some individual variations in sensitivity to optical feedback between lasers of the same structure. Optical feedback as small as −22 dB can cause a significant number of intensity dropouts from the main lasing mode in some units whereas other units can tolerate a −15 dB optical feedback without causing dropouts or degradation in the mode rejection ratio. By taking some simple steps in preventing reflections in fiber optic systems, it is shown that even the most sensitive C3 laser can be operated without penalty due to optical feedback. cleaved-coupled-cavity semiconductor lasers
Durable surfaces on zirconium fluoride glasses
Authors: Burman C. , Lanford W. A. , Doremus R. H. , Murphy Denis
Published: February 2003

Hydrogen profiles, Rutherford backscattering, and changes in pH of leaching solution show that zirconium fluoride glass surfaces formed directly from the melt can be much more durable than cut and polished surfaces.