bluuebunny/crossref_metadata_2025 huggingface dataset:
Cleaved-coupled-cavity lasers with large cavity length ratios for enhanced stability
Authors: Bowers J. E. , Bjorkholm J. E. , Burrus C. A. , Coldren L. A. , Hemenway B. R. , Wilt D. P.
Published: February 2003

The fabrication and operation of the first cleaved-coupled-cavity (C3) semiconductor lasers with large cavity length ratios are described. The internal cleaved facet is precisely positioned by photochemically etching a groove through most of the wafer. Single longitudinal mode operation is obtained over a temperature range of 21 °C and over a current range of threshold to greater than four times threshold. Sidemode suppression of 100:1 was measured when the laser was modulated at 350 MHz with an extinction ratio greater than 10:1. These results are experimentally and theoretically compared to approximately equal length C3 lasers.
Anomalous polarization characteristics of 1.3-μm InGaAsP buried heterostructure lasers
Authors: Craft D. C. , Dutta N. K. , Wagner W. R.
Published: February 2003

The stimulated emission from lasers with a linear light-current characteristic is polarized in the TE mode. For some lasers with a kink in the L-I curve, the kink represents the onset of a higher order TM polarized stimulated emission. Both TE and TM modes are present above the kink. These TE and TM emissions usually have separate groups of longitudinal modes. Under pulsed operation, the TE mode appears before the TM mode. X-ray diffraction measurements suggest the presence of an internal stress in lasers exhibiting stimulated TM emission. A possible explanation for the observation is discussed. The mechanism is based on (i) higher optical gain of the TM mode than that of the TE mode in the presence of a compressive stress and (ii) larger reflectivity of the higher order TM modes. The power output at which a kink appears can be increased by decreasing the active layer width.
Observation of gain in the violet bands of sodium vapor
Authors: Bahns John T. , Stwalley William C.
Published: February 2003

We report our observations attributable to optical gain through stimulated emission in the violet when sodium vapor is optically pumped with the 350.7-nm line of a krypton ion laser. In addition we present the accompanying fluorescence spectrum which shows previously unreported discrete structure on the short wavelength side of the violet bands.
Electronic and optical properties of p-type amorphous silicon and wide band-gap amorphous silicon carbide films prepared by photochemical vapor deposition
Authors: Inoue Takeshi , Tanaka Tatsuya , Konagai Makoto , Takahashi Kiyoshi
Published: February 2003

p-type hydrogenated amorphous silicon (a-Si:H) films were prepared by the mercury photosensitized decomposition of a disilane-diborane gas mixture. With increased gaseous impurity ratio (diborane/disilane), the dark conductivity was enhanced. However, the optical band gap was reduced with increasing boron concentration as generally observed in glow discharge produced boron-doped a-Si:H films. Wide optical gap (2.0–2.5 eV) hydrogenated amorphous silicon carbide (a-SiC:H) films were also prepared by the photochemical vapor deposition technique. Acetylene and dimethylsilane were used as the carbon source instead of methane which is usually used in glow discharge system. Moreover, wide optical-gap, p-type a-SiC:H films were photochemically prepared by adding diborane as an impurity to these gas mixtures. A dark conductivity of 3×10−7 (Ω cm)−1 was obtained for p-type a-SiC:H films with an optical band-gap energy of about 2.0 eV.
Detection of hydrogen induced Schottky barrier modulation in Pd/SiOx/a-Si:H diodes by photoemission with synchrotron radiation
Authors: Fortunato G. , D’Amico A. , Coluzza C. , Sette F. , Capasso C. , Patella F. , Quaresima C. , Perfetti P.
Published: February 2003

The Pd/SiOx/a-Si:H hydrogen sensor has been investigated by photoemission spectroscopy with synchrotron radiation. We measured directly the valence-band discontinuity and the built-in potential during the first stage of formation of the interface obtained by depositing thin amorphous silicon overlayers on Pd/SiOx substrates. Changes of the interface parameters were measured after hydrogen exposure and subsequent hydrogen removal with oxygen. Hydrogen sensitivity is related to hydrogen induced Schottky barrier modulation.
Low-temperature oxygen diffusion in silicon
Authors: Hansen W. L. , Pearton S. J. , Haller E. E.
Published: February 2003

Using the formation of the proposed neutral acceptor-hydroxyl complex AOH as a marker, the diffusion coefficient of a mobile oxygen species introduced in p-type silicon from a plasma source at near ambient temperatures is determined to be D0=3.0×10−10 exp(−3.0/kT) cm2 s−1. At 35 °C the diffusion of this unbound oxygen species is 30 times faster than the effective diffusion of atomic H introduced in a similar manner. An activation energy of 1.60 eV is found for the thermal dissociation of this oxygen species bound to boron.
Real and apparent effects of strong electric fields on the electron emission from midgap levels EL2 and EL0 in GaAs
Authors: Lagowski J. , Lin D. G. , Gatos H. C. , Parsey J. M. , Kaminska M.
Published: February 2003

The effects of strong electric fields, up to 4×105 V/cm, on the electron emission from the GaAs dominant midgap levels EL2 and EL0 were investigated by employing differential capacitance transients on GaAs-Au Schottky diodes. It was found that, in diodes with normal reverse bias characteristics, both levels exhibited a small field enhancement of electron emission, well within the range of the Poole–Frenkel effect. In contrast, very pronounced ‘‘apparent’’ electric field effects were observed in diodes with large reverse bias current. Thus, the conflicting reported results on the magnitude of the field enhancement of the electron emission from EL2 must be attributed to the characteristics of the Schottky diodes employed rather than to those of EL2.
Circuit equivalent to the elastic spherical shell
Authors: Hazony Dov
Published: February 2003

The pulsating elastic spherical shell is investigated in detail. A possible equivalent circuit is shown to contain two capacitors, two inductors, a transmission line, and an ideal transformer.
Local thermodynamic equilibrium in free-burning arcs in argon
Authors: Farmer A. J. D. , Haddad G. N.
Published: February 2003

Measurements of normalized radial emission coefficients in a free-burning arc in argon are presented as a function of position in the arc. The variation of these emission coefficients with pressure indicates departures from local thermodynamic equilibrium at 1-atm pressure.
Modeling of plasma devices for pulsed power
Authors: Kunc Joseph A. , Gundersen Martin A.
Published: February 2003

This letter considers quantitative models of microscopic processes in plasmas formed in gas phase devices for pulsed power. Although models have been developed for devices such as lasers, there are others, such as switches, where these processes have been treated only phenomenologically. Further, transport data must be adjusted to include the effects of high electron density. It is shown that it is necessary to use a microscopic model to correctly describe the device behavior. Examples presented include the effect of Coulomb collisions on conductivity in various gases, and the ionization processes in a hydrogen thyratron.
Graphoepitaxial alignment of KCl crystallites in the presence of water vapor
Authors: Kobayashi Toshio , Takagi Kazumasa
Published: February 2003

The graphoepitaxy of KCl was investigated through depositing the KCl film on a Si substrate having square-wave grating by means of vacuum evaporation, and then exposing the film to water vapor. The deposited crystallites grew to become rectangular parallelepipeds 3–4 μm in diameter because of the water adsorbed on the surface. During the growth, crystallite orientation was aligned along the grating by the effect of the groove walls. A well-aligned in-plane orientation was obtained when the groove width of the grating was kept smaller than the width of the grown crystallite and when the groove depth was close to the crystallite’s height.
Depth distributions of 1H, 2H, and 4He implanted into HgCdTe and CdTe measured by secondary ion mass spectrometry
Authors: Wilson R. G.
Published: February 2003

The capability to measure atom densities of 1H, 2H, and 4He in HgCdTe and CdTe above about 1018 cm−3 in background-subtracted cesium beam secondary ion mass spectrometry profiles has been demonstrated using ion implantation and implanted fluences. Range parameters are determined for ion energies between 150 and 300 keV. Projected ranges for 1H are slightly greater than those for 2H in both HgCdTe and CdTe. Hydrogen ion ranges are about 0.75 μm/100 keV of energy in both materials, and the third moment of the depth distributions is about −2.1.
Effects of implantation temperature on the properties of buried oxide layers in silicon formed by oxygen ion implantation
Authors: Tuppen C. G. , Taylor M. R. , Hemment P. L. F. , Arrowsmith R. P.
Published: February 2003

The effects of implantation temperature (Ti) on the chemical and physical structure of annealed high-dose oxygen ion implanted layers were investigated by Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). At low Ti (∼400 °C) the buried oxide is bordered by layers of polycrystalline silicon (polysilicon) which, in the top silicon layer, is separated from damaged single crystal Si by a thin band of discontinuous oxide. These polysilicon layers are formed from amorphous regions during high-temperature anneals. At high Ti (∼500 °C) polysilicon was not observed.
Ribbon-to-ribbon float zone single crystal growth stabilized by a thin silicon dioxide skin
Authors: Yablonovitch Eli , Gmitter Tom
Published: February 2003

We have found that a thin silicon dioxide skin stabilizes the float zone in ribbon-to-ribbon single crystal growth. 40-μm-thick single crystal ribbons, oriented 〈100〉 and scanned in the 〈011〉 direction, were grown completely free of subgrain as well as grain boundaries. This surprising suppression of low angle grain boundaries may be related to a similar effect which has been seen in supported thick silicon on SiO2 films.
Influence of substrate temperature on the formation of buried oxide and surface crystallinity during high dose oxygen implantation into Si
Authors: Holland O. W. , Sjoreen T. P. , Fathy D. , Narayan J.
Published: February 2003

The dependence of the implantation-induced morphology on substrate heating during high dose O+ irradiation of Si was investigated. For high dose oxygen implantation, a continuous buried oxide layer forms during implantation. It is shown that the damage morphology in the crystalline region ahead of the buried oxide is extremely sensitive to variations in the temperature of the substrate about 475 °C. Both backscattering/channeling spectroscopy and transmission electron microscopy were used in determining the microstructure of the implanted samples.
Temperature dependence of current gain in AlGaAs/GaAs heterojunction bipolar transistors
Authors: Chand Naresh , Fischer Russ , Henderson Tim , Klem John , Kopp William , Morkoç Hadis
Published: February 2003

Details of the temperature dependence of current gain in AlGaAs/GaAs heterojunction bipolar transistors (HBT’s) are reported for the first time. Unlike homojunction transistors, the gain initially increases with decreasing temperature from 425 K followed by a decrease towards 77 K at a temperature which is dependent on AlAs mole fraction in the emitter. Variation of gain with temperature is much smaller than what is normally seen in homojunction transistors adding another advantage in favor of the HBT’s. Hole injection current into the emitter and parasitic recombination currents are shown to be the reasons for the observed temperature dependence of gain.
Melt-width enhancement in the recrystallization of polycrystalline silicon-on-insulator by twin-laser-beam-induced substrate interheating
Authors: Sasaki Nobuo , Mukai Ryoichi , Izawa Tetsuo , Nakano Motoo , Takagi Mikio
Published: February 2003

A new method to recrystallize polycrystalline silicon on amorphous insulating layers is developed using twin cw argon laser beams. It is found that the melt width of twin beams can exceed that of a single beam by a factor of 4. This effect is explained by a model of substrate interheating between twin laser spots. Using this technique, a large silicon single crystalline grain as large as 1.8 mm long and 20 μm wide was obtained on thermal oxide coated silicon wafers even for the substrate kept at room temperature during laser irradiation.
Insular crystals in undoped GaAs single crystals: A probable source of dislocation
Authors: Cornier J. P. , Duseaux M. , Chevalier J. P.
Published: February 2003

We have observed particles of size ∼1000 Å in semi-insulating single crystal GaAs. Using diffraction, dark-field imaging and x-ray microanalysis in the electron microscope, we have identified one such particle as consisting of a polycrystalline GaAs insular. We propose that such insulars act as sources for dislocations.
Improvement of field-effect transistor threshold voltage uniformity by using very low dislocation density liquid encapsulated Czochralski-grown GaAs
Authors: Yamazaki Hajime , Honda Takashi , Ishida Satoru , Kawasaki Yasuhiro
Published: February 2003

Threshold voltage (Vth) uniformity in very low dislocation density liquid encapsulated Czochralski-grown GaAs was investigated. A standard deviation (σVth) of 13 mV was realized for Vth from the center part of the etch pit free area on the wafer. No correlation was observed between Vth and the distance from a field-effect transistor (FET) gate to its nearest neighbor etch pit. A σVth of 10 mV can be obtained by eliminating crystal dislocations and background fluctuations such as striations and also refining the FET fabrication process.
Crystalline characterization of Si/BP/Si heteroepitaxy
Authors: Amano Jun , Yoshida Tohru , Shono Katsufusa
Published: February 2003

Si(100)/BP(100)/Si(100) heteroepitaxial layers were successfully grown by a standard chemical vapor deposition method. The crystalline quality of the heteroepitaxial layers was investigated by MeV helium backscattering spectroscopy. The nature of crystalline defects was studied by cross-section transmission electron microscopy (TEM). A high density of structural defects was observed in the BP layers, especially at or near the interface between the BP layers and the Si substrates. The defect density of the top Si layers was much lower than that of the BP layers, and the crystalline quality of the top Si layer was very close to that of silicon on sapphire as observed by helium backscattering spectroscopy and cross-section TEM.
Boundary conditions on the minority-carrier concentrations of graded p-n junctions
Authors: Bhat K. N. , Sukulal K.
Published: February 2003

New boundary conditions on the minority-carrier concentrations, applicable to the junctions encountered in the present day solar cells and very large scale integrated circuits, are derived. The departure from the ideality in the current-voltage characteristics of these junctions is explained using the revised boundary conditions.
Temperature behavior of optical absorption in InGaAsP lasers
Authors: Dutta N. K. , Olsson N. A. , Shen T. M.
Published: February 2003

We have investigated the temperature dependence of the optical absorption in InGaAsP lasers emitting at 1.57 μm by measuring the resonant frequency as a function of output power at various temperatures. The results obtained using this technique are not influenced by leakage currents which can reduce the measured external differential quantum efficiency in some device structures. Our results show that the optical absorption does not vary significantly with increasing temperature which suggests that the threshold carrier density in 1.57-μm InGaAsP lasers is weakly temperature dependent. The latter is consistent with our recent measurement of threshold current using short electrical pulses where T0∼170 K was observed. Thus, the strong temperature dependence of threshold current of InGaAsP lasers is primarily due to the temperature dependence of the carrier lifetime at threshold. The shorter carrier lifetime (i.e., increased carrier loss) at high temperature can be due to Auger recombination.
High reflectivity GaAs-AlGaAs mirrors fabricated by metalorganic chemical vapor deposition
Authors: Thornton R. L. , Burnham R. D. , Streifer W.
Published: February 2003

We demonstrate the ability to grow optically reflective structures epitaxially on a GaAs substrate using the metalorganic chemical vapor deposition growth technique. This has been accomplished by depositing alternating quarter-wavelength layers of GaAs and (AlGa)As. By growing such structures with up to 80 total layers, we have produced near perfect (100% reflectivity) mirrors that are design wavelength selectable over a wide range. A theoretical calculation is presented which demonstrates the ability of these films to be grown with a wide range of reflectivities over a wide range of material compositions.
Microsecond room-temperature optical bistability and crosstalk studies in ZnS and ZnSe interference filters with visible light and milliwatt powers
Authors: Olbright G. R. , Peyghambarian N. , Gibbs H. M. , Macleod H. A. , Van Milligen F.
Published: February 2003

ZnS and ZnSe interference filters exhibit fast switch-on times (10 and 50 μs, respectively) with milliwatt powers at room temperature. The nonlinearity in the refractive index is found to result from heating by absorption. Crosstalk between two light beams is negligible for separations exceeding 20 μm with 7.7-μm beam diameters.
Real-time photoacoustic microscopy
Authors: Quimby R. S.
Published: February 2003

A new technique in photoacoustic microscopy is described in which a line scan photoacoustic image is displayed directly on an oscilloscope screen and can be observed to change in real time. The new method differs from conventional photoacoustic microscopy in that the beam position is modulated rather than the beam intensity, so that the spatial distribution of sample defects is mapped into the time domain. The result is a photoacoustic line scan image quite similar to that obtained in the conventional way, but acquired in a time measured in milliseconds rather than minutes.
Formation and growth of amorphous phases by solid-state reaction in elemental composites prepared by cold working
Authors: Atzmon Michael , Verhoeven John D. , Gibson Edwin D. , Johnson W. L.
Published: February 2003

Amorphous alloys of Ni-Zr and Cu-Zr have been synthesized by solid-state reaction of composite metal mixtures produced by mechanical deformation of metal powder mixtures and intercalated foil layers. The materials obtained were investigated by means of x-ray diffraction and differential scanning calorimetry. The results are compared with known data for thin films and rapidly quenched alloys.
In-gap optical absorption of amorphous Si3N4
Authors: Seager C. H. , Knapp J. A.
Published: February 2003

The optical absorption coefficient of thin films of chemically vapor deposited amorphous Si3N4 has been measured for photon energies ranging from 1.7 to 3.9 eV using photothermal deflection spectroscopy. From these data it can be inferred that these films contain between 10 and 100 ppm in-gap electronic states, a number consistent with estimates of the trapped charge density in metal-nitride-oxide-semiconductor devices. While other investigators have inferred the existence of well defined trap energies from electrical data, the present measurements yield only broad, rather featureless absorption spectra.
Modulation doping in GexSi1−x/Si strained layer heterostructures
Authors: People R. , Bean J. C. , Lang D. V. , Sergent A. M. , Störmer H. L. , Wecht K. W. , Lynch R. T. , Baldwin K.
Published: February 2003

We report the first observation of the modulation doping effect in Si/Ge0.2Si0.8 heterojunctions grown by molecular beam epitaxy. Peak hole mobilities of ∼3300 cm2 V−1 s−1 have been observed at 4.2 K. These values, although nonoptimum, are comparable to the best reported values for holes in Si/SiO2 inversion layers. Low temperature, angular dependent, Shubnikov–de Haas measurements have demonstrated the two-dimensional nature of the hole gas and yield a surface carrier density of 3.5×1011 cm−2. From the temperature dependence of the Shubnikov–de Haas amplitudes a hole effective mass of 0.30±0.02mo has been derived. Identical measurements on n-type heterojunctions having the same Ge content (x=0.2) have failed to show a sustained enhancement of mobility at low temperatures, indicating that ΔEv≫ΔEc.
Effect of photocarriers on acoustic wave propagation for measuring excess carrier density and lifetimes in silicon
Authors: Stearns R. G. , Khuri-Yakub B. T. , Kino G. S.
Published: February 2003

A new technique is described to measure temporal periodic fluctuations in the free-carrier density of silicon. It is based on the electronic dependence of the elastic constants, and involves the measurement of the perturbation in phase of an acoustic wave propagating through a region of modulated carrier density. An experiment is described in which the bulk lifetime of photogenerated carriers is determined using this technique. A theory is developed to predict the acoustic phase perturbation, and is found to agree well with experiment.
Continuous wave mode-locked neodymium:phosphate glass laser
Authors: Strobel Scott A. , Ho Ping-Tong , Lee Chi H. , Burdge Geoffrey L.
Published: February 2003

We report the first successful mode locking of a cw neodymium phosphate glass laser. Transform-limited, 80-ps pulses were generated at 1.054 μm.
Saturation in the transfer characteristics of (Al,Ga)As/GaAs modulation-doped field-effect transistors at 77 K
Authors: Masselink W. T. , Drummond T. J. , Klem J. , Kopp W. , Chang Y. C. , Ponse F. , Morkoç H.
Published: February 2003

Modulation-doped field-effect transistors operating under large forward gate biases at 77 K have been studied both experimentally and theoretically. The theoretical analysis includes the self-consistent solution of Schrödinger’s and Poisson’s equations in the GaAs channel and includes Fermi–Dirac statistics in the GaAs and AlGaAs. A dramatic decrease in transconductance is observed at large forward gate voltages and is explained within the theory as being due to limited two-dimensional electron gas concentration and the gate voltage dependence of the concentration of electrons bound to donors in the AlGaAs. The balance of dynamics of the Fermi level versus conduction-band energy and electron occupation of the relatively deep Si donors lead to the observed saturation in drain current versus gate voltage (transfer) characteristics.
Dynamic Burstein–Moss shift in GaAs and GaAs/AlGaAs multiple quantum well structures
Authors: Erskine D. J. , Taylor A. J. , Tang C. L.
Published: February 2003

Time-resolved studies of the dynamic Burstein–Moss shift of the absorption edge following intense photoexcitation are reported for room-temperature samples of GaAs and GaAs/AlGaAs multiple quantum well (MQW) structures. Band-filling times, which correspond to the redistribution of electrons from an energy of 0.5 eV above the bottom of the conduction band to an energy of 0.15 eV, are found to be 1.7 to 1.3 ps for GaAs in the carrier density range of 0.5–2.0×1019 cm−3 and 1 ps for a MQW structure at a density of 2×1019 cm−3. An approximate rate equation model is presented which agrees reasonably well with the experimental results.
Improved Schottky capacitance spectroscopy method for the study of interface states in metal-semiconductor junctions
Authors: Chekir F. , Barret C.
Published: February 2003

Schottky capacitance spectroscopy is an electrical method allowing the characterization of interface states at a metal-semiconductor junction. This method is based on the study of the capacitance of a forward biased Schottky diode as a function of bias, temperature, and frequency. The experimental procedure previously described presents the drawback of being very time consuming because of the need for low-frequency measurements. We describe here a new improved method allowing rapid and straightforward spectroscopy with high-energy resolution.
Quantum transport studies of grain boundaries in p-Hg1−xMnxTe
Authors: Grabecki G. , Dietl T. , Sobkowicz P. , Kossut J. , Zawadzki W.
Published: February 2003

We show that charged traps at grain boundaries in p-Hg1−xMnxTe lead to the formation of an inversion layer. The layers are dominant channels of electrical conductivity at low temperatures. By means of the Shubnikov–de Haas effect measurements we demonstrate that the electron gas in the layer forms a quasi-two-dimensional system. We determine electric subband populations and effective masses. We establish parameters of the potential well at the grain boundary within a simple model.
GaInAsP/InP buried heterostructure formation by liquid phase epitaxy
Authors: Logan R. A. , Temkin H. , Merritt F. R. , Mahajan S.
Published: February 2003

Two-step liquid phase epitaxy is shown to be impeded in the GaInAsP system by the difficulty of achieving uniform epitaxial wetting and highly radiative interfaces. This problem is most severe on the {111}In plane and could be due to a stochiometric disturbance at the etched surface due to unequal dissolution rates of the crystal components. Anodization etching to a depth between 430–860 Å removes this problem and permits reproducible formation of high quality epitaxial layers of InP on {111}In planes. The effectiveness of these cleaning procedures is demonstrated by the reproducible preparation of low threshold double channel planar buried heterostructure lasers.
InGaAsP/InP waveguide grating filters for λ=1.5 μm
Authors: Alferness R. C. , Joyner C. H. , Divino M. D. , Buhl L. L.
Published: February 2003

We report the first demonstration of InGaAsP/InP passive waveguide reflection grating filters. Waveguide filters with ∼1.5-μm center wavelength, peak reflectivity >99%, and spectral bandwidths (full width at half-maximum) as narrow as 6 Å and as broad as 130 Å have been achieved.
Proton spectra diagnostics for shock-compression studies
Authors: Welch D. R. , Harris D. B. , Bennish A. H. , Miley G. H.
Published: February 2003

The energy spectra of fusion products escaping long-pulse-length laser-imploded deuterium-tritium filled glass microballoons have been measured with a time-of-flight spectrometer. The D(d,p)T reaction proton energy spectra showed two distinct peaks, indicating two burn phases in the target. The first burn phase is attributed to a spherically converging shock, while the second is attributed to subsequent compression heating. The analysis of these spectra provides the first conclusive proof of significant compression yields in these targets, where approximately half of the yield occurs during the compression burn phase.
Angular velocity spread of relativistic photoelectrons induced by excimer laser irradiation
Authors: Kawai M. , Kawamura Y. , Toyoda K.
Published: February 2003

The angular velocity spread of relativistic photoelectrons induced by a pulsed excimer laser was measured. The energy, the current density, and the pulse duration of the accelerated photoelectron were 0.34 MeV, 0.5 A/cm2, and 20 ns, respectively. (The method of measurement is based on measuring Larmor radius which corresponds to the transverse component of the electron velocity.) The angular velocity spread β⊥/β∥ was found to be less than 8×10−3, which means that the energy component due to β⊥ was as small as ≲17 eV.
Transport studies of GaAs1−xSbx-AlyGa1−yAs strained-layer superlattices
Authors: Wei H. P. , Chou M. J. , Tsui D. C. , Klem J. , Morkoç H. , Wagner R. J.
Published: February 2003

Electrical transport in modulation-doped GaAs1−xSbx-AlyGa1−yAs strained-layer superlattices (SLS) grown by molecular beam epitaxy was studied, using low field Hall measurements from 4.2 to 300 K, high field quantum transport, and the far-infrared cyclotron resonance at 4.2 K. Our results show directly a degenerate two-dimensional electron gas in the SLS with an effective mass m*=0.063m0 and a mobility μ=7.7×103 cm2/Vs at a density ns =6.7×1011 cm−2, demonstrating the feasibility of high quality GaAs1−xSbx-AlyGa1−yAs SLS with good two-dimensional electronic transport properties despite the large lattice mismatch between the constituent layers.
Reduction of feedback-induced noise by high-reflectivity facet coating in single longitudinal mode semiconductor lasers
Authors: Kume M. , Shimizu H. , Itoh K. , Kano G. , Teramoto I.
Published: February 2003

The feedback-induced noise in single longitudinal mode semiconductor lasers is suppressed over a wide range of feedback light intensity by high-reflectivity facet coatings. A relative intensity noise value was as low as −140 dB/Hz under 1% optical feedback in the GaAlAs lasers with high-reflective (0.75) facets.
Hot-electron memory effect in double-layered heterostructures
Authors: Luryi S. , Kastalsky A. , Gossard A. C. , Hendel R.
Published: February 2003

We studied a memory effect due to the real-space hot-electron transfer between two conducting GaAs layers separated by a graded AlGaAs barrier. Application of a lateral electric field to one of the layers enhances its electron temperature and leads to a charge injection into the other layer which is kept floating. As the heating voltage is removed, the injected electrons remain in the second layer, giving rise (at low temperatures, 77 K) to a persistent potential difference. Kinetics of the charge-up process are studied at different heating voltages.
Growth of undoped, high purity, high resistivity ZnSe layers by molecular beam epitaxy
Authors: Yoneda Kiyoshi , Hishida Yuji , Toda Tadao , Ishii Hiroaki , Niina Tatsuhiko
Published: February 2003

The growth of undoped, high purity ZnSe layers by molecular beam epitaxy with extremely high purity Se source materials refined by sublimation is described. The resistivity of these layers is greater than 104 Ω cm. In low-temperature photoluminescence spectra, only free-exciton emission line becomes dominant and all the bound exciton emission lines are extinguished, which is characteristic of very high purity ZnSe. Detailed behavior of electrical and optical properties of normally undoped layers is remarkably dependent on the purification cycles of Se materials used as source materials. The results indicate that the high resistivity of undoped, high purity ZnSe layers is due to a reduction of residual donor impurities.
HgCdTe-Cr interface chemistry
Authors: Peterman D. J. , Franciosi A.
Published: February 2003

The microscopic interaction of Hg1−xCdxTe surfaces with refractory metals was examined through synchrotron radiation photoemission studies of HgCdTe cleaved in vacuum and of HgCdTe-Cr junctions formed in situ. The results indicate that strong Te-Cr interdiffusion is accompanied by rapid Hg depletion of the surface layer. In sharp contrast to similar studies of simple and noble metals on HgCdTe, variations in the surface anion-to-cation ratio and the Hg-to-Cd ratio do not affect the interface position of the Fermi level. The strongly inverted character of the near-surface region found after cleaving appears to be preserved during the Hg-Cr exchange reaction.
Optical properties of GaAs on (100) Si using molecular beam epitaxy
Authors: Masselink W. T. , Henderson T. , Klem J. , Fischer R. , Pearah P. , Morkoç H. , Hafich M. , Wang P. D. , Robinson G. Y.
Published: February 2003

Undoped GaAs layers have been grown on (100) oriented Si by molecular beam epitaxy and have been studied using photoluminescence, photographic, and x-ray measurements. To minimize antiphase disorder, an As primer layer was successfully used to initiate the polar on nonpolar growth. Photoluminescence spectra show the presence of five bands into which the luminescence from each sample falls. The energy variation within any given band was less than 4 meV. X-ray and photoluminescence analysis appear to indicate some strain in the crystal. Although very preliminary, the results obtained indicate that GaAs on Si can potentially be used for a number of hybrid ciruits.
Fluorine-enhanced thermal oxidation of silicon in the presence of NF3
Authors: Morita M. , Kubo T. , Ishihara T. , Hirose M.
Published: February 2003

The oxidation rate of silicon has been dramatically increased at temperatures between 600 and 800 °C by adding NF3 gas to a dry oxygen atmosphere. The chemical analysis of the resulting oxide has revealed that fluorine atoms in SiO2 are incorporated as Si–F bonds. The existence of such bonded-fluorine atoms enhances the diffusion of oxidant through the oxide layer. The oxidation reaction rate in the SiO2-Si interface is also remarkably increased because fluorine atoms in the interface create silicon dangling bonds and weakly positively charged silicon atoms as well. The kinetics of the fluorine-enhanced oxidation has primarily been interpreted in terms of the Deal–Grove model.
Field influence on deep level transients at large deep to shallow trap ratios
Authors: Morante J. R. , Samitier J. , Cornet A. , Herms A.
Published: February 2003

The differential capacitance method is used to determine the enhancement of thermal emission rates by electric field. The customary analysis is modified for large ratios of deep and shallow trap concentrations. Experimental results are given for the DX center in AlxGa1−xAs at x=0.55.
Chemical trends in the activation energies of D
X centers
Authors: Kumagai O. , Kawai H. , Mori Y. , Kaneko K.
Published: February 2003

The activation energies of DX centers in AlGaAs doped with six different impurities (S, Se, Te, Si, Ge, and Sn) are measured by deep level transient spectroscopy. Remarkable trends are established, in which the activation energies of DX centers with group IV impurities become shallower as the mass number of the impurity increases, while those with group VI impurities remain constant.
Self-sustained picosecond pulse generation in a GaAlAs laser at an electrically tunable repetition rate by optoelectronic feedback
Authors: Lau K. Y. , Yariv A.
Published: February 2003

We demonstrate that applying optoelectronic feedback to a high-speed, self-pulsing semiconductor laser is an effective and practical means of generating picosecond optical pulses (∼10–20 ps) at a very high repetition rate, between 1 to 5 GHz, which can be electrically tuned. The optical pulses are very stable both on a short term basis with a frequency stability of one part in 105, and on the long term basis as a result of the absence of critical optical alignment. This laser system is potentially very useful in high-speed electro-optic signal processing, optical multiplexing, or laser ranging.
Anomalous photomagnetoresistance effect in modulation-doped AlGaAs/GaAs heterostructures
Authors: Luryi S. , Kastalsky A.
Published: February 2003

A novel negative photoresistance effect at Al0.3Ga0.7As/GaAs interface in the presence of a magnetic field B is discovered and explained. At low temperatures (T=4.2 K) illumination of the sample leads to a persistent electron accumulation in the GaAs channel (the well-known persistent photoconductivity effect). In the presence of B≳0.3 T the dependence of the longitudinal resistance (as measured by the four-probe method) shows an anomalous behavior in that the resistance increases sharply with the increasing concentration n of carriers provided by light. In the same range of concentrations the longitudinal resistance at fixed n is proportional to B2. It is shown that the observed behavior of the resistance is associated with photoexcitation of electrons from donor vacancy (DX) centers in the highly doped AlGaAs region resulting in the creation of a second conducting layer of high charge density and low mobility.
Titanium disilicide formation by wide-area electron beam irradiation
Authors: Moore Cameron A. , Rocca J. J. , Collins G. J. , Russell P. E. , Geller J. D.
Published: February 2003

We describe the use of a wide-area (38 cm2) electron beam as a heat source to interdiffuse 400-Å-thick sputter-deposited titanium films into 3–6-Ω cm〈100〉 n-type silicon wafers. Isochronal exposures of 30 s with electron beam of current densities greater than 250 mA/cm2 reduced the as-deposited sheet resistance by a factor of 10, while exposures at half this current caused the sheet resistance to increase by a factor of 2.5. Compositional depth profiles obtained from a combination of ion beam sputtering and Auger electron spectroscopy show that this resistivity increase is caused by diffusion of oxygen into the titanium film induced by the electron beam heating. At exposures to beam intensities sufficient to induce complete silicide formation, oxygen is segregated at the surface by the advancing silicon. We conclude that the silicide self-cleanses itself of oxygen during formation.
Substitutional nitrogen impurities in pulsed-laser annealed silicon
Authors: Murakami Kouichi , Itoh Hisayoshi , Takita Kôki , Masuda Kohzoh
Published: February 2003

Single-crystal Si samples with nitrogen (N) impurities (Si:N) and with N and phosphorus (P) impurities (Si:N:P) have been investigated by electron spin resonance measurements. It was found that substitutional N impurities Ns cannot be incorporated into Si by cw laser annealing of N ion-implanted Si or by N doping during crystal growth; however, Ns is incorporated into Si by pulsed-laser annealing (PLA) of N ion-implanted Si. The spin density of Ns decreases with doping of P shallow donors into PLA Si:N and increases by introduction of slight point defects in PLA Si:N:P. These results suggest that Ns with a negative charge are formed in PLA Si: N:P system.
Self-interstitial enhanced carbon diffusion in silicon
Authors: Kalejs J. P. , Ladd L. A. , Gösele U.
Published: February 2003

Out-diffusion of carbon from silicon wafers during annealing at 900 °C is observed to be enhanced by the in-diffusion of phosphorus as compared to annealing in a nitrogen ambient. This diffusion enhancement is suggested to be due to phosphorus-induced silicon self-interstitials and an appreciable diffusion component of carbon in silicon involving self-interstitials.
Growth and patterning of GaAs/Ge single crystal layers on Si substrates by molecular beam epitaxy
Authors: Sheldon P. , Jones K. M. , Hayes R. E. , Tsaur B-Y. , Fan John C. C.
Published: February 2003

Single crystal GaAs layers have been grown on Si substrates with an intermediate Ge layer. Both the Ge and subsequent GaAs are grown in situ by molecular beam epitaxy (MBE). Cross-sectional transmission electron microscopy studies show GaAs surface dislocation densities on the order of 107 cm−2. The quality of the GaAs is indicated by a mobility within 15% of that measured on GaAs/GaAs MBE structures doped at the same level. This material also exhibits a photoluminescence signal with a room-temperature intensity about 50% of GaAs grown on GaAs, and with a similar half-width. In this letter, electron diffraction, optical and electrical data are presented for n-type GaAs/Ge/Si structures. In addition, a selective lift-off technique is demonstrated, with possible applications in the development of monolithic GaAs/Si integrated circuits.
Temperature dependence of the electron mobility in GaAs-GaAlAs heterostructures
Authors: Mendez E. E. , Price P. J. , Heiblum M.
Published: February 2003

We have studied the temperature dependence of the mobility of two-dimensional electron gases formed at the interface of high-quality GaAs-GaAlAs heterostructures, focusing on the temperature range 4–40 K. The inverse mobility is shown to increase linearly with temperature, with a slope which increases with the electron density and is independent of the zero-temperature mobility. The results are consistent with a theoretical model for the acoustic-phonon mobility that includes screening, indicating that the temperature dependence in high mobility GaAs-GaAlAs structures is dominated by phonons rather than ionized impurities. A good agreement between theory and experiment is found using a value of 13.5 eV for the deformation potential of GaAs.
Electron acceleration by laser driven plasma waves in inhomogeneous plasmas
Authors: Takada Youichi , Nakano Noboru , Kuroda Hiroto
Published: February 2003

A new method of electron acceleration by laser driven plasma waves is proposed. The method takes advantage of the phase matching between injected electrons and plasma waves. The phase of electrons in electrostatic waves can be controlled by changing the plasma electron density spatially along the direction of electron propagation. From numerical results, by assuming 1.05-μm, 30-ps laser pulse with 1017 W/cm2 which is attainable today, it is shown that electrons are successfully accelerated from 1 MeV to 1 GeV in a distance of 18 m. It is also numerically shown that the phase stability is as good as that of conventional linacs.
Proposed new class of optically pumped, quasi-cw, ultraviolet and extreme ultraviolet lasers in the Be isoelectronic sequence
Authors: Krishnan Mahadevan , Trebes James
Published: February 2003

Intense line radiation from plasmas of Mn VI, P IX, Al V, Al VIII, Al IX, and Al XI may be used to selectively pump population inversions in plasmas of C III, N IV, F VI, Ne VII, Na VIII, and Mg IX. Quasi-cw lasing is possible on 4p–3d and 4f–3d transitions at wavelengths 2177 –230 Å. At the extreme ultraviolet wavelengths, 1-J, 10-ns laser output pulses at 108 W power levels are shown possible with existing discharge and laser technology.
Cavityless optical bistability due to light-induced absorption in cadmium sulfide
Authors: Dagenais M. , Sharfin W. F.
Published: February 2003

Cavityless, whole-beam optical bistability in thin, uncoated cadmium sulfide platelets is observed at milliwatt power levels when a cw laser is tuned near a sharp extrinsic excitonic resonance in cadmium sulfide (the I2 bound exciton). Very large contrast ratios between the on and off states are measured. The detuning and temperature dependence of the bistability results are reported. Preliminary transient measurements are also discussed.
Observation of supermodes in a phase-locked diode laser array
Authors: Paoli Thomas L. , Streifer William , Burnham Robert D.
Published: February 2003

Phase-locked diode laser arrays have been observed to oscillate in collective modes (supermodes) characteristic of a composite waveguide formed as a result of optical coupling between the fields of individual waveguides in the array. For an array of 11 gain-guided lasers, as many as five different supermodes oscillated simultaneously at wavelengths separated by approximately 0.3 Å. Each supermode was identified by spectrally resolving the spatial profile of the optical intensity on the laser facet.
Soft x-ray spectral characterization of resist polymer using synchrotron radiation
Authors: Mochiji Kozo , Kimura Takeshi , Obayashi Hidehito , Yanagihara Mihiro
Published: February 2003

Soft x-ray absorption spectra and spectral sensitivity of x-ray resist, poly-2-methylpentene-1-sulfone, are studied using synchrotron radiation. Shape resonance around the S2p edge and chemical shift among C1s levels are observed in the absorption spectra. The degradation efficiency of the resist is found to vary with incident photon wavelength.
Concentration of electrons in selectively doped GaAlAs/GaAs heterojunction and its dependence on spacer-layer thickness and gate electric field
Authors: Hirakawa K. , Sakaki H. , Yoshino J.
Published: February 2003

The concentration Ns of two-dimensional electrons in N-GaAlAs/GaAs systems is studied; Ns shows a systematic decrease when the thickness Wsp of an undoped GaAlAs ‘‘spacer layer’’ is increased. Such a dependence is shown to be well explained by the theory in which the size quantization is taken into account. Furthermore, Ns is studied as a function of gate voltage in field-effect transistor (FET) structures and found to saturate once Ns reaches its limiting value. This phenomenon is strongly dependent on Wsp and is well ascribed to the formation of nondepleted region in the GaAlAs layers. Implications for FET designs are discussed.
Transient frequency shift induced by the electron density in injection locking of transversely excited atmospheric CO2 lasers
Authors: Cassard P. , Lourtioz J-M.
Published: February 2003

The time-dependent discharge electron density of transversely excited atmospheric (TEA) CO2 lasers is shown to induce large frequency upshifts of the injection locking band from the TEA laser cavity resonance. The single mode laser frequency measured at the pulse onset was also upshifted. Both the TEA laser and the cw CO2 injecting laser were heterodyned at high frequency with a common cw N2O laser local oscillator. The injecting laser, which provided the scanning frequency, was used for monitoring the TEA laser cavity reflection. At different pumping powers, voltage-current characteristics have been measured for estimating the electron density. A comparison of the estimated frequency shifts to the measured frequency shifts is reported.
Symmetry and electronic properties of the oxygen thermal donor in pulled silicon
Authors: Henry P. M. , Farmer J. W. , Meese J. M.
Published: February 2003

Oxygen is the dominant impurity in pulled silicon. At 450 °C, thermal donors form in oxygen rich silicon. Using deep level transient spectroscopy, this donor is found to have an energy level of 0.142 eV below the conduction band at zero electric field, exhibiting behavior consistent with the Poole–Frenkel field assisted electron emission process. Using deep level transient spectroscopy in conjunction with calibrated uniaxial stress, we have determined the symmetry of the neutral 450 °C oxygen donor complex to be D2d. Possible models for the oxygen donor complex are presented which are consistent with the observed symmetry and with previous experiments.
Photoconductivity of sputtered CuxS films
Authors: McLeod Paul S. , Partain Larry D. , Sawyer Dave E. , Peterson Terry M.
Published: February 2003

The optical band edge of reactively sputtered CuxS films has been determined to be 1.18±0.03 eV using a technique in which the conductance of the films with respect to the wavelength of the incident light was measured. These results were found to confirm optical absorption data on CuxS films. Also, the efficiency of a 6.0% solar cell which was made using this sputtering technique is reported.
Time-resolved temperature measurement of pulsed laser irradiated germanium by thin-film thermocouple
Authors: Baeri P. , Campisano S. U. , Rimini E. , Zhang Jing Ping
Published: February 2003

Iron-constantan thin film thermocouples overlaid with Ge layers 1 μm thick are used to measure the temperature-time dependence during irradiation with nanosecond Nd glass laser pulses. The response of the thermocouple is fast enough to allow the measurements of the temperature rise and fall. The obtained temperature values are in good agreement with the thermal model of laser annealing.
Photoluminescence study of nitrogen implanted silicon
Authors: Alt H. Ch. , Tapfer L.
Published: February 2003

Silicon crystals are implanted with nitrogen in the dose range of 1010–1016 ions/cm2. After thermal annealing at 700 °C photoluminescence at 1.1223 eV (A line) is observed which was reported previously only from bulk doped crystals. The dependence on the implantation dose and the annealing behavior of the recombination center are investigated in detail. We find that electrically active nitrogen is not responsible for the formation of the defect whereas there exists a correlation with vacancy-interstitial nitrogen complexes.
Spectral characteristics of (GaAl)As diode lasers at 1.7 K
Authors: Harrison J. , Mooradian A.
Published: February 2003

The spectral broadening as a function of output power for transverse junction stripe (GaAl)As diode lasers has been measured at 1.7 K. The power-independent linewidth was observed to be about 30 MHz in reasonable agreement with the model involving electron number fluctuations in the device.