bluuebunny/crossref_metadata_2025 huggingface dataset:
The trend of deep states in organometallic vapor-phase epitaxial GaAs with varying As/Ga ratios
Authors: Bhattacharya P. K. , Ku J. W. , Owen S. J. T. , Aebi V. , Cooper C. B. , Moon R. L.
Published: February 2003

Traps in organometallic vapor-phase GaAs have been characterized. The dominant electron trap present in conventional vapor-phase epitaxial GaAs is also present in organometallic GaAs with an activation energy ΔE0T +ΔEB=0.820.02 eV and a capture cross section σ∞= (1.71.0) ×10−14 cm2. A linear dependence of the trap concentration on As/Ga ratio in the material indicates the involvement of a Ga vacancy in the formation of the center. A second electron trap with an activation energy of 0.360.02 eV and hole traps with activation energies of 0.30 and 0.35 eV have been identified and their capture cross section and density determined.
Interference effects on the surface of Nd:YAG-laser-reacted Pd-silicide
Authors: Affolter K. , Lüthy W. , Wittmer M.
Published: February 2003

The generation of silicides by laser irradiation of Pd-coated Si wafers is often associated with circular ripple patterns formed in the irradiated area. These surface modulations are explained by inhomogeneous reaction of Pd with Si due to interference effects in the incident laser beam.
Evidence for tunneling in reverse-biased III-V photodetector diodes
Authors: Forrest S. R. , DiDomenico M. , Smith R. G. , Stocker H. J.
Published: February 2003

Photodiodes made from III-V group semiconductor alloys have been found to exhibit anomalously high dark currents. We present evidence that tunneling is the dominant source of dark current in many cases. The tunneling current becomes substantial at peak junction electric fields as low as 105 V/cm due to the small direct energy gaps and small effective masses of the materials tested. Tunneling sets limits on the magnitude of the electric field attainable in these materials, and therefore has serious implications on photodetector design and performance.
Relationship between trapped holes and interface states in MOS capacitors
Authors: Hu Genda , Johnson Walter C.
Published: February 2003

Metal–silicon-dioxide–silicon capacitors with dry-grown oxides, when stressed at fields of 7.1–7.5 MV/cm with field plate positive at 90 K, showed buildup of trapped holes. Interface states appeared only after the samples were warmed. The number of interface states generated in one hour at either 20 or 66 °C was linearly proportional to the number of trapped holes, and the number of states generated in the central 0.7-eV portion of the Si bandgap during one year’s storage at room temperature was essentially equal to the original number of trapped holes. These results provide quantitative evidence of a cause and effect relationship between trapped holes and interface states in the Si-SiO2 system.
Interfacial order in epitaxial NiSi2
Authors: Chiu K. C. R. , Poate J. M. , Feldman L. C. , Doherty C. J.
Published: February 2003

High-quality epitaxial NiSi2 films have been fabricated on 〈111〉 Si substrates and examined by grazing-angle Rutherford backscattering and channeling techniques. The channeled backscattering yields are close to single-crystal values and permit examination of the silicide-silicon interface. The yields indicate that the number of disordered Ni atoms at the interface must be less than 1.5×1015 Ni/cm2.
Monte Carlo simulation of registration signals for electron beam microfabrication
Authors: Lin Yi-Ching , Adesida Ilesanmi , Neureuther Andrew R.
Published: February 2003

Monte Carlo calculations based on a continuous-slowing-down-approximation (CSDA) model have been carried out to study the backscattered electron image formation of a 54.6° tapered etched step registration mark in silicon. It is found that the energy signal gives slightly better contrast and greater average slope than the number signal. The constrast increases with step depth and is very close to its maximum value of 1.4 when the step depth is increased to 40% of the Bethe range of the primary beam. Additional step depth will degrade the signal shape. A universal curve of the average signal slope as a function of the normalized horizontal mark transition is also presented.
Fluorine-enhanced plasma growth of native layers on silicon
Authors: Chang R. P. H. , Chang C. C. , Darack S.
Published: February 2003

Fluorine-enhanced low-temperature (⩽600 °C) plasma growth of oxides and nitrides from Si has been studied. It is shown that the growth rates are greatly increased by incorporation of less than 1/2 atomic percent fluorine into the films. Auger profiles of fluorine-enhanced-plasma-grown SiO2 films show that they are nearly indistinguishable from those grown thermally. Uniform silicon oxynitride films (with N/O concentration ratios near 2) of thicknesses over 1000 Å can be grown in about four hours.
Intense lithium, boron, and carbon beams from a magnetically insulated diode
Authors: Neri J. M. , Hammer D. A. , Ginet G. , Sudan R. N.
Published: February 2003

A magnetically insulated diode, driven by a Marx generator, is used to produce intense pulsed beams of lithium, boron, or carbon ions. The type of ion is determined by the choice of material for the anode plasma source. The voltage pulse is typically 300 ns long with a peak voltage of 300 kV. The ion beams have peak current densities of 40–50 A/cm2.
Laser light absorption by a plasma with a very steep density gradient
Authors: Banfi G. P. , Gobbi P. G. , Morosi S. , Reali G. C.
Published: February 2003

We investigated the behavior of reflectivity versus angle of incidence of a Cu target irradiated by 4-ps laser pulses at 1.06 μm. From the data taken at 1013–1014 W/cm2 we show that optical resonance takes place also in the presence of very steep density gradients of the order of ∼0.15 μm. The role of collisions is discussed and illustrated by measurements taken at lower fluxes.
Dual electron injector structure
Authors: DiMaria D. J. , Dong D. W.
Published: February 2003

Experimental results are presented which show for the first time that stacked chemically vapor-deposited insulator combinations such as Si-rich-SiO2–SiO2–Si-rich-SiO2 sandwiched between Si or metal electrodes can be tailored to give any desired injection current characteristic for positive and negative voltage biases. The Si-rich-SiO2–SiO2 interfaces give enhanced electron injection into the SiO2 layer. By modifing this interface and the Si-rich SiO2 layer (for example, by changing its Si content), current voltage characteristics for each of the two interfaces of the Si-rich SiO2 injecting material with the SiO2 layer can be modified as desired. These dual electron injector structures DEIS’s are discussed with respect to optimizing the write and erase characteristics of nonvolatile semiconductor memories using a floating polycrystalline-silicon storage layer with a DEIS sandwiched in between it and a control gate.
Liquid-phase-epitaxy homostructure Pb0.85Sn0.15Te diode laser with controlled carrier concentration
Authors: Oron M. , Zussman A.
Published: February 2003

Homostructure Pb0.85Sn0.15Te diode lasers were fabricated from a liquid-phase-epitaxy grown n+ -p-p+ layer structure. Pulsed threshold currents as low as 40 A/cm2 at 17 °K and 1.5 kA/cm2 at 77 °K were measured. High external and internal quantum efficiencies of 17 and 34%, respectively, were found at 40 °K. No degradation of the threshold current was detected after fifteen thermal cycles.
n-CdS/p-Si heterojunction solar cells
Authors: Coluzza C. , Garozzo M. , Maletta G. , Margadonna D. , Tomaciello R. , Migliorato P.
Published: February 2003

The photovoltaic properties of n-CdS/p-Si heterojunctions prepared by vacuum deposition of CdS:In on single-crystal silicon substrates are reported. Power conversion efficiencies of 9.5% (cell area 1.5 cm2) have been obtained. The I-V characteristics and their temperature dependance suggest tunneling as the dominant conduction mechanism.
Bounds on the complex dielectric constant of a composite material
Authors: Milton G. W.
Published: February 2003

A generalization of the bounds obtained by Wiener and by Hashin and Shtrikman is derived for complex dielectric constants.
Picosecond pulse generation by passive mode locking of diode lasers
Authors: Ippen E. P. , Eilenberger D. J. , Dixon R. W.
Published: February 2003

We report the generation of pulses as short as 5 psec in duration by passive mode locking of a modified strip buried heterostructure GaAlAs diode in an extended resonator. We also describe the effects of intercavity bandwidth control for the generation of transform-limited pulses. E/T;8042.80.−f, 42.55.Px
The effect of As2 and As4 molecular beam species on photoluminescence of molecular beam epitaxially grown GaAs
Authors: Künzel H. , Ploog K.
Published: February 2003

The first observation of several sharp photoluminescence lines with energies less than the energy of the recombination peak associated with the exciton bound to the neutral carbon acceptor in nominally undoped p-type GaAs grown by molecular beam epitaxy (MBE) is reported. The lines ranging from 1.5110 to 1.5040 eV are interpreted as radiative recombination of defect-induced bound excitons directly correlated with the interaction of As4 molecular beam species during MBE growth. These lines disappear totally when As2 instead of As4 beams are used. We then demonstrate that all sharp photoluminescence features, previously only detected in the best LPE samples, are now also observed in thin MBE GaAs layers when grown from As2 beam species.
Crystal orientation dependence of ionization rates in germanium
Authors: Mikawa T. , Kagawa S. , Kaneda T. , Toyama Y. , Mikami O.
Published: February 2003

Ionization rates in 〈111〉 and 〈100〉 germanium are determined experimentally. The ionization rates obtained are expressed as α=2.72×106 exp(−1.1×106/E), β=1.72×106 exp(−9.37×105/E) for 〈111〉 and α=8.04×106 exp(−1.4×106/E), β=6.39×106 exp(−1.27×106 /E) cm−1 for 〈100〉 where α and β are ionization rates for electrons and holes, respectively, and E is the electric field. Hole- to electron-ionization-rate ratios of 〈100〉 Ge are found to be greater than those of 〈111〉 Ge. The multiplication noise power of Ge avalanche photodiodes calculated by using the ionization rates obtained shows good agreement with experimental results.
Laser-photoinduced etching of semiconductors and metals
Authors: Haynes R. W. , Metze G. M. , Kreismanis V. G. , Eastman L. F.
Published: February 2003

Etched patterns with submicron resolution have been produced using laser-induced photodissociation of dissolved and complexed halogens in liquid solution. Tentative mechanisms for this photoinduced dissociation process are presented.
Supersaturated metastable Ag-Ni solid solutions formed by ion beam mixing
Authors: Tsaur B. Y. , Mayer J. W.
Published: February 2003

Extension of terminal solid solubilities has been achieved by ion beam mixing in the almost completely immiscible Ag-Ni system. Multi-layered samples of thin deposited Ag-Ni films of various compositions were bombarded with energetic Xe ions at temperatures from −190 to 250 °C. Supersaturated Ag- and Ni-rich fcc solid solutions were obtained, as indicated by x-ray and electron diffraction. Analyses of lattice parameters showed that the solubility range for the metastable solid solutions produced by low-temperature bombardment was wider than for those formed at high temperature. Maximum solubilities were determined to be 4.5 at. % Ni in Ag and 16 at. % Ag in Ni if one assumes the ion-induced fcc phases to be ideal solid solutions. The effects of implantation temperature on the formation of metastable phases are discussed.
Sensitive i
n s
i
t
u trace-gas detection by photothermal deflection spectroscopy
Authors: Fournier D. , Boccara A. C. , Amer Nabil M. , Gerlach Robert
Published: February 2003

We present a sensitive (5ppb for ethylene, 10−7 cm−1) and simple photothermal scheme for the detection of trace gases and measuring weak absorption in gas-phase samples. We also demonstrate the feasibility of this scheme for performing in situ measurements in the absence of sample cells or containers, thus eliminating the drawbacks of sampling and sampling techniques. Factors limiting our detectivity are discussed, and a comparison to the thermal lens effect is made.
Studies by cross-sectional transmission electron microscope of InAs grown by molecular beam epitaxy on GaAs substrates
Authors: Chang Chin-An , Serrano C. M. , Chang L. L. , Esaki L.
Published: February 2003

We have used the cross-sectional transmission electron microscope to study InAs grown by molecular beam epitaxy. For the InAs films directly grown on GaAs, the dislocation density at the InAs-GaAs interface is several orders of magnitude higher than that in the bulk films. Those grown by the step grading technique show strong interactions among dislocations at the interfaces, and a much reduced dislocation density in the thin InAs layers.
High-Δn optical waveguides in LiNbO3: Thallium-lithium ion exchange
Authors: Jackel Janet
Published: February 2003

Waveguides with large Δne have been fabricated in x-cut LiNbO3 using ion exchange in a TlNO3 melt. The exchange was carried out at ∼240 °C, producing surface index increases of Δne ≅0.12–0.13. No increase in Δn0 was seen. A simple index profile resulting in the best fit to the observed mode structure is a step-index profile. Analysis of the diffusion process shows that such a profile can be produced by ion exchange in which self-diffusion coefficients of the two counterdiffusing species are concentration dependent. This provides the first direct evidence that ion exchange occurs in LiNbO3.
cw carbon monoxide laser with microwave excitation in the supersonic flow
Authors: Hoffmmann P. , Hügel H. , Schall W. , Schock W.
Published: February 2003

A new technique of efficiently coupling microwave energy into a supersonic gas flow is described. A stable self-sustained 2.45-GHz microwave discharge is applied to excite a cw CO gasdynamic laser. Electron densities well above the cutoff value have been achieved together with a reduced field strength within the discharge that is appropriate for efficient vibrational excitation. With an energy loading of 0.15 eV/molecule CO a laser power of 285 W was obtained in a small-scale flow channel at an overall efficiency of 6%.
Four-wave polarization spectroscopy of small-gap semiconductors: Application to free carrier concentration measurements in gallium arsenide using a tunable infrared source
Authors: Kupecek Ph. , Comte M. , Chemla D. S.
Published: February 2003

We present a generalization of the polarization coherent anti-Stokes Raman spectroscopy to zinc-blende structure semiconductors. Competitive third-order processes have been put in evidence by studying the resonant signal around the LO phonon at 292 cm−1 in GaAs. Our analysis enables us to compare directly Raman and free-carrier contributions whose concentration can be thus measured by a purely optical method.
Vibration quenching of HgBr(X 2Σ+1/2)
Authors: Helvajian H. , Wittig C.
Published: February 2003

We report a study of the time evolution of different groups of HgBr (X2Σ+1/2) vibrational level densities which are quenched by collisions with He. Vibrational quenching is efficient down to the lowest v″ levels that we are able to monitor, indicating that energy can be efficiently extracted from the HgBr (B→X) laser, even when tuning to frequencies other than those with the highest gain.
Return-current electron streams in high-intensity laser target interaction
Authors: Jaanimagi P. A. , Ebrahim N. A. , Burnett N. H. , Joshi C.
Published: February 2003

X-ray streak photography of the interaction of a nanosecond CO2 laser pulse with large-diameter foil targets shows the presence of an annular x-ray emitting region which expands away from the focal spot with a veclocity up to 109 cm/sec. This region exhibits laser-polarization-dependent asymmetry, and it is postulated that it is formed by a return current of fast electrons bombarding the front of the target foil. It appears likely that this phenomenon is responsible in part for anomalous lateral energy transport and magnetic field generation in such experiments.
Storage of ions from laser-produced plasmas
Authors: Knight R. D.
Published: February 2003

A laser-produced plasma has been shown to be an effective means of producing metal ions, which are subsequently stored in an ion trap. The output from a Nd:YAG laser is focused onto targets, including Be, C, Al, Fe, and Pb, at the edge of an electrostatic ion trap. Typically 2×108 ions are trapped with storage times greater than 100 msec. Only singly charged ions are observed. The ion trap used for this work is a novel electrostatic trap having a harmonic axial potential. Properties of the plasma are measured by using the trap as a Langmuir probe.
Nonradiative recombination in InGaAsP/InP light sources causing light emitting diode output saturation and strong laser-threshold-current temperature sensitivity
Authors: Uji T. , Iwamoto K. , Lang R.
Published: February 2003

Nonradiative recombination with the rate strongly dependent on the injected carrier density n as αn2–4 has been found to be the cause of the output saturation in 1.3-μm InGaAsP/InP surface emitting double heterostructure light emitting diodes. It has been found that this nonradiative recombination is also responsible for the strong temperature sensitivity of InGaAsP/InP double heterostructure laser threshold current.
Pressure and impulse on an aluminium target from pulsed laser irradiation at reduced ambient pressure
Authors: Dufresne D. , Bournot Ph. , Caressa J. P. , Bosca G. , David J.
Published: February 2003

An experimental investigation of the time-dependent pressure induced on an aluminium target from a pulsed CO2 laser irradiation at reduced ambient density has been made. As the pressure of the air surrounding the target decreases from 760 to 0.5 Torr, the width of the pressure pulse on the target becomes narrower, and the amplitude of the pressure increases. A pressure as high as 1.7 kbar and a mechanical coupling of 20 dyn sec J are obtained.
Imaging of the silicon on sapphire interface by high-resolution transmission electron microscopy
Authors: Ponce Fernando A. , Aranovich Julio
Published: February 2003

The silicon-sapphire interface of CVD silicon on a (11̄02) sapphire substrate has been studied by high-resolution transmission electron microscopy. Cross-section images of the interface are presented where the silicon and sapphire lattices are directly resolved. The images show that the interface is planar and abrupt to the limit of resolution (less than 3 Å). Defect anisotropy is evident and can be linked to tilt of the [100] direction of the silicon layer with respect to the normal to the substrate.
Optical pumping and the valence-band light-hole effective mass in GaxIn1−xAsyP1−y (y≃2.2x)
Authors: Hermann Claudine , Pearsall Thomas P.
Published: February 2003

We report the use of optical pumping in p-type GaxIn1−xAsyP1−y nearly lattice-matched to InP. Analysis of the conduction-electron spin-polarized photoluminescence has been used to deduce the valence-band light-hole effective mass as a function of alloy composition. Our results are in good agreement with masses calculated using the k⋅p approximation.
Effect of mode coupling on optical bistability in a bidirectional ring cavity
Authors: Agrawal Govind P.
Published: February 2003

In a ring cavity the counter-propagating modes are coupled through a homogeneously broadened atomic medium. The mode coupling is shown to introduce novel features in the transmission characteristics of two simultaneous bistable switches. We suggest suitable materials and discuss possible applications of the predicted effect.
Fundamental line broadening of single-mode (GaAl)As diode lasers
Authors: Fleming Mark W. , Mooradian Aram
Published: February 2003

The spectral width of (GaAl)As cw single-mode diode lasers varied linearly with reciprocal output power at 300 K with a slope 50 times greater than that predicted by the Schawlow-Townes expression without partial inversion. While the spectral narrowing observed at 77 K for constant mode power is consistent with the predicted temperature dependence of the partial inversion contribution, the magnitude of the broadening can not completely be attributed to partial inversion.
Synchronously pumped mode-locked GaAs laser
Authors: Cao Wei-Lou , Vacher Aileen M. , Lee Chi H.
Published: February 2003

A temporally coincident picosecond pulse train from a mode-locked GaAs laser was produced using two-photon excitation from a mode-locked Nd:glass laser. The single pulse width measured by a sum frequency technique was 7 ps or less.
Mechanism for injecting contact formation at metal-CdS or CdSe interfaces
Authors: Freeman E. C. , Slowik John H.
Published: February 2003

The electrical performance of single-element metallic contacts on CdS and CdSe is classified according to a simple scheme. It is shown that the valence of reactive metals correlates with barrier height, which we relate to a simple doping effect. By considering practical constraints as well as electrical performance, In is identified as being a uniquely useful element for forming an injecting electrode on these semiconductors.
High-temperature cw and pulsed operation in constricted double-heterojunction AlGaAs diode lasers
Authors: Botez D. , Connolly J. C. , Gilbert D. B.
Published: February 2003

Constricted double-heterojunction diode lasers of positive-index lateral guiding and low-threshold-current design are found to operate cw to 170 °C (ambient temperature) and pulsed to 280 °C. High threshold-current temperature coefficients (T0≳230 °C) and constant differential quantum efficiencies are found up to 100 °C. Above 100 °C the temperature-dependent current-focusing effect responsible for high-T0 behavior appears to saturate. Single-longitudinal-mode cw operation is recorded up to 150 °C. Two effects, a strong temperature dependence of the threshold current density above 180 °C (T′0 = 40–50 °C), and sublinear spontaneous emission above 220 °C, are believed to reflect the same nonradiative Auger recombination process currently proposed to explain InGaAsP laser behavior near room temperature.
Structure and compression of crystalline argon and neon at high pressure and room temperature
Authors: Finger L. W. , Hazen R. M. , Zou G. , Mao H. K. , Bell P. M.
Published: February 2003

Argon and neon crystallize in the face-centered cubic structure (Fm3m, z = 4) at 11.5±0.5 and 47.4±0.5 kbar, respectively, at 293 K. Single-crystal cell dimensions were obtained at 82 kbar for argon and 144 kbar for neon with high-pressure, x-ray diffraction techniques. The data were corrected to 0 K and fitted to a second-order Murnaghan equation of state with V0 and K0 constrained to results obtained in low-temperature experiments. No solid-solid phase transitions are observed to the highest pressures studied.
Generation of subpicosecond pulses from an actively mode locked GaAs laser in an external ring cavity
Authors: van der Ziel J. P. , Logan R. A. , Mikulyak R. M.
Published: February 2003

We report the active mode locking of the emission from a GaAs buried optical guide laser in an external ring cavity. The two counter rotating pulses interact in the laser which in addition to the gain medium contains a saturable absorber at one facet introduced by proton bombardment at 600 keV with a 3×1015 cm−2 dosage level. Bursts of pulses with 0.56 psec FWHM at a 625-MHz repetition rates have been obtained.
Identification of quench origins in a superconductor with acoustic emission and voltage measurements
Authors: Tsukamoto O. , Maguire J.F. , Bobrov E.S. , Iwasa Y.
Published: February 2003

The acoustic emission and voltage measurements were used to identify quench sources in a current-carrying superconductor. The sources identified were (i) conductor motion, (ii) epoxy cracking, and (iii) pure joule heating resulting from the conductor reaching critical current. The combination of these two techniques appears to be a promising diagnostic tool in probing premature quenches in superconductors and superconducting magnets.
Broadband tunable picosecond semiconductor lasers
Authors: Damen T. C. , Duguay M. A. , Shah J. , Stone J. , Wiesenfeld J. M. , Logan R. A.
Published: February 2003

Intense photoexcitation of GaAs by picosecond laser pulses creates a superdense electron-hole plasma (∼1020 cm−3) which sustains laser action from 8900 Å in the IR to 7700 Å in the visible. Tunable picosecond laser pulses are obtained by moving a slightly wedged ultrashort cavity in the focus of the pump laser pulse.
The longitudinal stability of intense nonrelativistic particle bunches in resistive structures
Authors: Channell Paul J. , Sessler Andrew M. , Wurtele Jonathan S.
Published: February 2003

The longitudinal stability of intense particle bunches is investigated theoretically in the limit of small wall resistivity compared to total reactance. It is shown that both in the absence of resistivity and to lowest order in the resistance that an intense bunch is stable against longitudinal collective modes. An expression is derived for the lowest order instability rate. Application of these results are made to drivers for heavy ion inertial fusion.
Phase-matched sum-frequency light generation in optical fibers
Authors: Sasaki Y. , Ohmori Y.
Published: February 2003

The generation of phase-matched two-wave sum-frequency light is observed in optical fibers. A Q-switched and mode-locked Nd:YAG laser is used as a pump laser. The two-wave sum-frequency light is generated from the pump and the first two Roman Stokes lines. Phase matching is achieved by using the dispersion of the waveguide modes to compensate for bulk dispersion. Conversion efficiencies of 1.1×10−3 and 0.5×10−3 from the pump into the two-wave sum-frequencies, whose peak wavelengths are 0.54 and 0.56 μm, respectively, are obtained with an 0.8-kW peak pump power at 1.064 μm.
Characteristics of ablation plasma from planar, laser-driven targets
Authors: Grun J. , Decoste R. , Ripin B. H. , Gardner J.
Published: February 2003

The momentum, energy, and velocity characteristics of plasma ablating from planar targets irradiated by long Nd-laser pulses (4 ns,<1014 W/cm2) are measured and the dependence of ablation parameters upon absorbed irradiance is determined. Large laser spots are used in these experiments so that the results are not sensitive to boundary effects.
Velocity field characteristics of minority carriers (electrons) in p-In0.53Ga0.47As
Authors: Degani J. , Leheny R. F. , Nahory R. E. , Heritage J. P.
Published: February 2003

Steady-state velocity field characteristics for photoexcited minority electrons in p-In0.53Ga0.47As are reported. A low-field drift mobility of 6000 cm2/V s for ∼1017 cm−3 impurities and a high-field drift velocity of 2.6×107 cm/s at 7.5 kv/cm are found. There is no evidence of transferred electron effects, a result which we attribute to energy scattering by holes and which leads to an enhancement of electron drift velocity.
Transparent and highly conductive films of ZnO prepared by rf reactive magnetron sputtering
Authors: Webb J. B. , Williams D. F. , Buchanan M.
Published: February 2003

Highly conductive films of zinc oxide have been prepared by reactive rf magnetron sputtering from an oxide target. Film conductivities ranging from ∼10−8 Ω−1 cm−1 to 5×102 Ω−1 cm−1 can be obtained depending on the sputter conditions. Films with sheet resistivities of 85 Ω/⧠ showed little absorption and ∼90% transmission between λ = 4000→8000 Å. A second low power discharge at the substrate is used to initiate growth of the highly conducting material on room-temperature substrates. Thus, during the deposition of insultating ZnO, turning on this second discharge causes the deposition to ’’switch’’ from low conductivity to high conductivity material. This is of particular interest in the fabrication of semiconductor-insulator-semiconductor solar cells where precise control over the thickness of the insulating layer is necessary and where a highly transparent and conductive window-junction layer is required.
Hot-carrier effects in 1.3-μ In1−xGaxAsyP1−y light emitting diodes
Authors: Shah J. , Leheny R. F. , Nahory R. E. , Temkin H.
Published: February 2003

We report the first observation of carrier heating effects for In1−xGaxAsyP1−y 1.3-μ light emitting diodes, including variation of carrier temperature with injection current and ambient temperature. These results demonstrate that carrier temperature reaches 400 K at 2.5×104 A/cm2 (260 mA) for an LED with room-temperature ambient. Such significant heating must be taken into account in modeling device performance.
Measurement of GaAs field-effect transistor electronic impulse response by picosecond optical electronics
Authors: Smith P. R. , Auston D. H. , Augustyniak W. M.
Published: February 2003

Direct time-resolved measurements of the linear and nonlinear electronic impulse response of a high-speed gallium arsenide metal semiconductor field-effect transistor have been made by using picosecond optical pulses to drive high-speed photoconducting electronic pulse generators and sampling gates. High resolution, jitter-free measurements with excellent signal-to-noise showed the field-effect transistor to have a fast full width at half-maximum response of approximately 25 ps, and a slower fall time of 75 ps.
Enhancement of electron impact ionization in a superlattice: A new avalanche photodiode with a large ionization rate ratio
Authors: Capasso F. , Tsang W. T. , Hutchinson A. L. , Williams G. F.
Published: February 2003

The first superlattice avalanche photodiode (APD) is reported. The high field region of this p-i-n structure consists of 50 alternating Al0.45Ga0.55As (550 Å) and GaAs (450 Å) layers. A large ionization rate ratio has been measured in the field range (2.1–2.7)×105 V/cm, with α/β≃10 at a gain of 10 giving a McIntyre noise factor Fn = 3. The ionization rate ratio enhancement with respect to bulk GaAs and AlGaAs is attributed to the large difference in the band edge discontinuities for electrons and holes at the heterojunction interfaces. The superlattice APD is a new device concept which can be used to develop low noise APD’s in a variety of III-V materials including long wavelength 1.3–1.6-μm semiconductors.
Deep center EL2 and anti-Stokes luminescence in semi-insulating GaAs
Authors: Johnson E. J. , Kafalas J. , Davies R. W. , Dyes W. A.
Published: February 2003

We have observed efficient photoluminescence upconversion in semi-insulating GaAs. This upconversion is apparently associated with a two-step excitation of the deep level EL2 as indicated by the excitation spectrum. Assessment of these results along with results in the literature suggests that this center is due to an arsenic antisite defect. Line shape analysis indicates that clustering of acceptors occurs near the site of the defect. These results provide insight into the agents responsible for the semi-insulating property of undoped GaAs.
Multidimensional quantum well laser and temperature dependence of its threshold current
Authors: Arakawa Y. , Sakaki H.
Published: February 2003

A new type of semiconductor laser is studied, in which injected carriers in the active region are quantum mechanically confined in two or three dimensions (2D or 3D). Effects of such confinements on the lasing characteristics are analyzed. Most important, the threshold current of such laser is predicted to be far less temperature sensitive than that of conventional lasers, reflecting the reduced dimensionality of electronic state. In the case of 3D-QW laser, the temperature dependence is virtually eliminated. An experiment on 2D quantum well lasers is performed by placing a conventional laser in a strong magnetic field (30 T) and has demonstrated the predicted increase of T0 value from 144 to 313 °C.
Calculation of deep state profiles from transient capacitance data
Authors: Rockett P. I. , Peaker A. R.
Published: February 2003

Several analytical methods have been published for determining the spatial variation of deep level concentrations from depletion profiling measurements. These methods require the numerical differentiation of experimental data. In this letter we report results of a precise computer simulation of capacitance transient experiments which show the need to take account of the trap depth below the conduction band when calculating concentrations and the problems involved in numerically differentiating experimental data. We have extended the simulation program to yield a completely general iterative profiling scheme which does not employ numerical differentiation. This new method is compared with existing analytical techniques and is shown to possess significantly greater accuracy.
Outdiffusion of the main electron trap in bulk GaAs due to thermal treatment
Authors: Makram-Ebeid S. , Gautard D. , Devillard P. , Martin G. M.
Published: February 2003

The profile of the main electron trap in bulk GaAs has been studied following thermal treatments with different capping and implantation conditions. Considerable departure from an idealized outdiffusion behavior (error function) is observed and this is attributed to surface As loss. The extent of the surface redistribution of EL2 is comparable to, or more important than that frequently observed for the Cr impurity.
Extremely low threshold (AlGa)As graded-index waveguide separate-confinement heterostructure lasers grown by molecular beam epitaxy
Authors: Tsang W. T.
Published: February 2003

Extremely low threshold GRIN-SCH lasers with single and double active layers were prepared by molecular beam epitaxy as a result of an increased optical confinement, a significant reduction in the internal loss αi, and the increased gain constant β. Averaged Jth 250 A/cm2 and 160 A/cm2 for broad-area Fabry–Perot diodes of cavity lengths 380 and 1125 μm, respectively, and averaged external differential quantum efficiency ηD of 65–80 % were obtained.
Hydrogen passivation of copper-related defects in germanium
Authors: Pearton S. J.
Published: February 2003

The passivation of deep acceptor level defects (Ev +0.33 eV, Ev +0.19 eV) associated with copper in single-crystal germanium by reaction with atomic hydrogen has been observed using deep level transient spectroscopy. The concentration profile of the Ev +0.33 eV center is presented as a function of the duration and temperature of the exposure to atomic hydrogen—when exposed for 3 h at 300 °C, 90% of the acceptor defects were passivated to a depth of ∼80 μm.
Pulsed XeCl laser annealing of ZnS:Mn thin films
Authors: Reehal H. S. , Gallego J. M. , Edwards C. B.
Published: February 2003

We describe pulsed XeCl (308 nm) laser annealing of ZnS thin films implanted with Mn ions and deposited onto single-crystal Si substrates. Successful annealing of the films only occurs when the specimens are held under inert gas pressure of several atmospheres during the laser pulse in order to obtain melting and regrowth of the films without appreciable vaporization. Typically, specimens annealed under 90 pounds per square inch, gauge (psig) of Ne at laser energy densities in excess of ∼0.8 J cm−2 exhibit a higher Mn photoluminescence signal than comparable samples thermally annealed at 500 °C, the difference being a factor of ∼2 at 2.5 J cm−2. Evidence for increased crystallinity in these specimens after laser annealing has also been obtained.
Improving the bulk laser damage resistance of potassium dihydrogen phosphate crystals by pulsed laser irradiation
Authors: Swain J. , Stokowski S. , Milam D. , Rainer F.
Published: February 2003

We have obtained an increase (factors of 1.5–3.0) in the threshold fluence for laser-induced inclusion damage in crystals of potassium dihydrogen phosphate (KDP) by irradiating the crystals at a fluence below that necessary to cause damage with a single laser pulse (1064-nm, 1-ns). The threshold increase was greatest for less damage resistant samples.
Laser crystallization of Si films on glass
Authors: Lemons R. A. , Bosch M. A. , Dayem A. H. , Grogan J. K. , Mankiewich P. M.
Published: February 2003

By using glass substrates which approximate the thermal expansion of a deposited Si film, thermal stress cracking during laser crystallization is eliminated. Results on three types of transparent silicate glass are reported. Chemical vapor deposition is used to coat these substrates first with a buffer layer of SiO2 or Si3N4 and then with a Si film. When the Si films are melted with an argon ion laser beam, large crystal grains are produced. Secondary ion mass spectroscopy is used to determine the effectiveness of the buffer layer in isolating the Si from impurities in the glass.
Picosecond InP optoelectronic switches
Authors: Foyt A. G. , Leonberger F. J. , Williamson R. C.
Published: February 2003

Proton bombardment is used to increase the response speed of InP optoelectronic switches. Photoconductivity measurements indicate response times following bombardment of <100 ps, with the electron mobility estimated to be ⩾600 cm2/Vs. This mobility is over an order of magnitude larger than that observed in similar high-resistivity devices of comparable speed fabricated in germanium or silicon-on-sapphire.
Laser-driven electron acceleration by means of two-wave interaction
Authors: Pantell R. H. , Smith T. I.
Published: February 2003

Two-wave electron acceleration is analyzed where one field is a slow microwave signal and the other is a laser light beam. An acceleration gradient of 1.0 GeV/m is achievable with a laser field strength of approximately 1010 V/cm.
Optically pumped mode-locked InGaAsP lasers
Authors: Putnam R. S. , Roxlo C. B. , Salour M. M. , Groves S. H. , Plonko M. C.
Published: February 2003

We report tunable cw mode-locked laser action from synchronously pumped InGaAsP lasers with an output power of 2 mW. Nearly bandwidth-limited pulses of 6-ps duration have also been obtained using a mechanically chopped pump beam. 2–5-μm-thick LPE quaternary layers lasing at 1.1 and 1.2 μm are longitudinally pumped by a Kr+ laser. Peak output powers of greater than 25 W, tunable over a 25-nm range, can be achieved. Unmode-locked operation has also been accomplished.
Single mode, piezoelectrically tuned, picosecond short-cavity dye laser
Authors: Cox A. J. , Merritt Charles D. , Scott Gary W.
Published: February 2003

This letter reports a piezoelectric-translator-tuned, short-cavity picosecond dye laser. This laser, pumped by second or third harmonic picosecond pulses from a mode-locked Nd+3: glass laser, has been operated at cavity lengths which allow only a single longitudinal mode within the lasing bandwidth of a typical dye gain curve. By varying the cavity length with the piezoelectric translator, the output wavelength has been continuously tuned. With different mirror sets and dyes, the lasing output can be varied across the visible spectrum. The laser output is characterized by a modewidth of 0.3 nm (multimode) and 1.5 nm (single mode). The energy conversion efficiency was found to be roughly 0.3% for single-mode operation and ≳3% for multimode operation at 600 nm.
Formation of dislocations during liquid encapsulated Czochralski growth of GaAs single crystals
Authors: Duseaux Marc , Jacob Guy
Published: February 2003

Results of calculations on thermal stresses induced during pulling of GaAs ingots are reported. Comparison between these calculations and our experimental results shows that the dislocations nucleation in crystals during growth cannot be directly related to a constant value of the critical resolved shear stress (CRSS). According to experiments performed on other materials, it is concluded that the CRSS can strongly depend upon the initial state of the material, and particularly upon temperature and native defects concentration and mobility.
Noninvasive analysis of InP surfaces using Hg-InP Schottky barrier diodes
Authors: Pressman L. D. , Forrest S. R. , Bonner W. A. , Van Uitert L. G.
Published: February 2003

Capacitance-voltage characteristics of Hg-InP Schottky barrier diodes are compared with those of Au-InP Schottky diodes. We show that the Hg-InP Schottky diode may be used as a sensitive, relatively nondestructive probe of the InP surface. In contrast, electronic analysis of Au-InP Schottky barrier diodes yields information about the InP surface after it has been altered in the evaporation process. Using Hg-InP Schottky diodes, thin insulating layers have been detected on InP exposed to wet chemical etchants, and surface charge has been detected on InP exposed to very low energy Ar plasmas.
Particle size distribution of Ni microprecipitates in LaNi5 used for hydrogen storage
Authors: Cohen R. L. , Sherwood R. C. , West K. W.
Published: February 2003

LaNi5 is an intermetallic compound which absorbs and desorbs hydrogen at convenient temperatures and pressures. It has been used for storing hydrogen fuel, and, using the heat of absorption, for various pump and heat engine applications. Recurrent absorption and desorption of hydrogen produces a phase separation into nickel metal and lanthanum hydride. We show from the magnetic behavior of degraded LaNi5 that a bimodal particle size distribution is present with all particles <(100 Å)3. The magnetic properties may be useful for determining the condition of LaNi5 in a reservoir.
Evidence of the role of boron in undoped GaAs grown by liquid encapsulated Czochralski
Authors: Ta L. B. , Hobgood H. M. , Thomas R. N.
Published: February 2003

We provide experimental evidence of electrical activity correlated with residual boron impurities and native point defects in undoped liquid-encapsulated Czochralski GaAs crystals. In Ga-rich samples containing ≥1017 cm−3 boron, an 0.073-eV acceptor level is observed in which the concentration increases with Ga and B content. An approximately quadratic increase in the concentration of the 0.073-eV defect acceptor is observed with increasing boron concentration, suggesting that a complex involving boron with an intrinsic defect (VAs, Gai, or GaAs ) is responsible for the observed acceptor behavior. No evidence of electrically active boron or boron complexes was found in semi-insulating GaAs pulled from stoichiometric or As-rich melts.
Temperature dependence of silicon Raman lines
Authors: Tsu Raphael , Hernandez Jesus Gonzalez
Published: February 2003

The one-phonon and two-phonon Raman spectra have been measured in the temperature range 20–900 °C. The rate of decrease of the normalized frequencies with increase of temperature for the zone center, TO at L and TA at X, is 5.4×10−5/°C, while for TO at X and TA at L is lower, being 3.6×10−5/°C. We have also found that the relative intensity of Stokes and anti-Stokes components of the Γ-point optical phonon deviates significantly from the value involving only the phonon occupation number, particularly at high temperatures. The decrease of the Γ25′ phonon from 521 cm−1 at 20 °C to 493 cm−1 at 900 °C should provide an unambiguous determination of the surface temperature due to laser heating.
Oxidation of silicon surfaces by CO2 lasers
Authors: Boyd I. W. , Wilson J. I. B.
Published: February 2003

We report for the first time, the use of a focussed CO2 laser beam and a controlled oxygen atmosphere to induce localized oxidation on the surface of a silicon wafer. These thin oxide films have been compared by infrared spectrometry with thin furnace-grown layers. We conclude that the laser-grown oxides are compositionally similar to conventional layers, and can be described by the formula SiO2. In contrast the half-width of the Si-O stretching vibration at 1070 cm−1 was found to be consistently less than for furnace-grown oxides. By fabricating simple Al-SiO2-Si-Al diodes, the dielectric properties of the films have been studied.
High power coupled multiple stripe quantum well injection lasers
Authors: Scifres D. R. , Burnham R. D. , Streifer W.
Published: February 2003

Operation of a coupled multiple stripe quantum well injection laser array is described. The device emits up to 400 mW of continuous output power and 2.1 W of peak pulsed (75 ns) output power from an uncoated mirror facet. Its far-field pattern is invariant to over three times threshold, and over 140 mW cw are coupled into a 100-μm core 0.3-numerical aperture (N.A.) optical fiber.
Are interface states consistent with Schottky barrier measurements?
Authors: Freeouf J. L.
Published: February 2003

Many Schottky barrier heights have less dependence upon metal work function than the simple work function matching model of this interface proposed by Schottky 40 years ago. The conventional explanation for this result involves the assumption that interface states of high density change their occupancy in response to work function differences and thereby reduce the variation of Schottky barrier heights. Such states could also change their occupancy under bias variations, and transport measurements have been interpreted in this fashion. We show that these latter assumptions also imply that the Schottky barrier height should itself be strongly altered by bias—a conclusion inconsistent with the results of capacitance and current transport experiments.
New lead alloy tunnel junction for quasiparticle mixer and other applications
Authors: Gundlach K. H. , Takada S. , Zahn M. , Hartfusse H. J.
Published: February 2003

We report on Pb/Bi/In-oxide-Pb/Bi sandwich films which appear to be particularly suitable for quasiparticle heterodyne mixers and video detectors. This junction shows good stability under thermal cycling; its gap voltage is 0.4–0.5 mV higher and the nonlinearity of the I-V curve is stronger than the recently successfully used Pb/In/(Au)-oxide-Pb/Bi junction. Critical current densities up to 1600 A/cm2 have been obtained so far.
Picosecond electro-optic sampling system
Authors: Valdmanis J. A. , Mourou G. , Gabel C. W.
Published: February 2003

We report the construction of a sensitive electro-optic sampling system for the measurement of ultrafast electrical transients. This system has a temporal resolution of lessthan 4 ps (over 100- GHz bandwidth), better than 50-μV sensitivity and potential for a temporal resolution reaching the single picosecond. Demonstrated applications are ultrafast photodetector response characterization and time resolved photoconductivity.
Thermal diffusivity of optical fibers measured by photoacoustics
Authors: Chardon Dominique , Huard Serge J.
Published: February 2003

We report the first measurement of the thermal diffusivity of an optical fiber using a photoacoustic (PA) technique. The absorption of a modulated light in the fiber core induces heat which diffuses through the optical cladding. The phase delay connected with the PA signal is directly related to the thermal diffusivity χ. We have obtained χ = 1.21×10−7±0.03 m2/s for a standard fiber. Although this value is smaller than the bulk diffusivity of ordinary glasses it has been measured on the real sample which is a drawn material.
Resistance probe for energetic particle dosimetry with applications for plasma edge studies
Authors: Wampler W. R.
Published: February 2003

Changes in the electrical resistance of thin carbon films caused by implantation with hydrogen, deuterium, and carbon ions were measured for various incident energies and for particle fluences in the range from 1012 to 1017 at./cm2. At low fluences the resistivity change is found to be proportional to the displacement damage caused by the incident particles. A model is presented which can be used to calculate the resistance change which is in good agreement with the measurements. It is proposed that by measuring the resistance change for carbon films exposed to the edge of magnetically confined plasmas the energy and the flux of incident ions and neutral atoms may be determined.
Pulse dispersion and preheating effects in ultrafast photoconductive detectors: In0.53Ga0.47As as example
Authors: Bimberg D.
Published: February 2003

The finite longitudinal optical phonon emission time of hot carriers created by nonresonant excitation of short channel photoconductive detectors and the momentum distribution of these electrons are shown to be limiting factors for the response of the detector to an infinitely narrow pulse. Pulse dispersion of the order of 40 ps is caused in In0.53Ga0.47 As/InP detectors with 10-μm channel width after nonresonant excitation at 820 nm in agreement with most recent experiments. Resonant excitation is imperative for a photoconductive detector of ultimate time resolution and sensitivity.