bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective interhalogen etching of tantalum compounds and other semiconductor materials
Authors: Ibbotson D. E. , Mucha J. A. , Flamm D. L. , Cook J. M.
Published: July 2002

We find that gaseous ClF3 is an effective and selective etchant for a variety of transition metals and metal compounds. Kinetics were studied for etching α-Ta (13–16 atom % N), Ta2N, and Ta2O5 in this gas, as a function of temperature and pressure, to provide effective activation energies of 4.0, 4.4, 7.7 kcal/mole, respectively. Relative etch rates measured in CF4/O2 and NF3 plasmas indicate that ClF3 gaseous etching has more than an order of magnitude better selectivity for nonoxidic metal compounds over the corresponding oxide. At 100 °C, selectivity for etching α-Ta or Ta2N over Ta2O5 is more than 160:1. Other materials used in semiconductor manufacture, such as SixNy, W, TaSi2, and photoresist, were also briefly surveyed and the results suggest ClF3 holds promise for isotropic etching applications that require high selectivity.
Optical waveguide detection: Photodetector array formed on the waveguide utilizing laser recrystallized silicon
Authors: Wu R. W. , Boyd J. T. , Timlin H. A. , Jackson Howard E. , Janning John L.
Published: July 2002

Integrated detection of light propagating in an optical waveguide with a photodetector array fabricated directly on the waveguide surface is demonstrated. Laser recrystallization of polycrystalline silicon is utilized. Periodically spaced antireflection stripes are used to confine grain boundaries formed during laser recrystallization to the area under these stripes, with photodetector elements formed on single crystal grains between the stripes. Regions containing the grain boundaries are then removed by plasma etching. Lateral p-i-n photodiode elements formed by ion implantation are characterized by reverse leakage currents <10−11 A and breakdown voltages of 40–80 V. Dynamic ranges over which the optical response is linear are measured to be 55–60 dB.
Stabilization and luminescent properties of GaP/GaAs0.4P0.6 strained-layer superlattice electrodes
Authors: Johnson Phelps B. , Ellis Arthur B. , Biefeld R. M. , Ginley D. S.
Published: July 2002

Photoelectrochemical cells based on n-GaP/n-GaAs0.4P0.6 strained-layer superlattice (SLS) electrodes have been stabilized against photocorrosion in an aqueous (di) telluride electrolyte, and show monochromatic optical to electrical energy conversion efficiencies of a few percent. The near-band-gap photoluminescence (PL) of the SLS electrodes exhibits field-induced quenching in rough accord with a dead-layer model. Electroluminescence (EL) is observed when the SLS’s are used as cathodes in a formamide/Na2S2O8 electrolyte. The EL and PL spectral distributions are similar.
Reduction of electromigration in gold thin films in the presence of hydrogen
Authors: Rodbell K. P. , Ficalora P. J.
Published: July 2002

Electromigration lifetime experiments have been completed on Au thin-film interconnects (Au, 0.5 μm thick and 25 μm wide) in vacuum (5×10−8 Torr) and in both hydrogen (H2) and helium (He) ambients (10 Torr). Results show that electromigration is drastically suppressed in the H2 environment with a greater than tenfold increase in lifetime realized.
Si-implanted and disordered stripe-geometry AlxGa1−xAs-GaAs quantum well lasers
Authors: Gavrilovic P. , Meehan K. , Guido L. J. , Holonyak N. , Eu V. , Feng M. , Burnham R. D.
Published: July 2002

The Si impurity is implanted into an AlxGa1−x As-GaAs quantum well heterostructure to form, by impurity-induced layer disordering and donor doping, a stripe-geometry buried heterostructure laser.
Efficient, damage resistant LiNbO3 acousto-optic waveguide deflector
Authors: Miyawaki Mamoru , Ogura Shigetaro
Published: July 2002

An efficient, damage resistant, guided wave deflector in LiNbO3 has been fabricated by a combination of titanium diffusion, proton exchange in benzoic acid with lithium benzoate, and post-annealing processes. The stability of the waveguide has been confirmed using x-ray rocking curves. The insertion loss of interdigital transducer and the diffraction efficiency were found to depend on the wave number of OH absorption produced by proton exchange.
Direct evidence for co-aggregation of carbon and oxygen in Czochralski silicon
Authors: Shimura F. , Hockett R. S. , Reed D. A. , Wayne D. H.
Published: July 2002

Direct evidence for the co-aggregation of oxygen and carbon is shown by secondary ion mass spectroscopy for a carbon-doped Czochralski silicon crystal subjected to a heat treatment at 1000 °C. In conjunction with infared absorption data, the carbon enhancement effect on oxygen precipitation at 1000 °C in high carbon silicon is explained with the catalytic effect of carbon in modifying the interfacial energy or the point defect ambient at the oxygen precipitate surface.
EL2-related defects in neutron irradiated GaAs1−xPx alloys
Authors: Muñoz E. , García F. , Jimenez B. , Calleja E. , Gomez A. , Alcober V.
Published: July 2002

The generation of EL2-related defects in GaAsP alloys by fast neutron irradiation has been studied through deep level transient spectroscopy and photocapacitance techniques. After irradiation p-n junctions were not annealed at high temperatures. In the composition range x>0.4, fast neutrons generate a broad center at Ec−0.7 eV that it is suggested to belong to the EL2 family. The presence of photocapacitance quenching effects has been taken as a preliminary fingerprint to make the above assignment. From computer analysis of the nonexponential transient capacitance waveforms, evidence that neutron irradiation creates a family of midgap levels, EL2-related, is found.
Anomalous voltage-controlled negative resistance in Pt-insulator-conductive polymer-Au junctions
Authors: Murao Kenji , Suzuki Kazuhiro
Published: July 2002

Anomalous electrical properties have been found for platinum-insulator-polypyrrole-gold junction cells where the insulator layer is doped with a small amount of polypyrrole. The electroformed samples exhibit voltage-controlled negative resistance (VCNR) with an exceptionally low peak voltage of 1.75 V. Linear sweeps of dc voltages between 0 and 3 V result in a switching phenomenon in which a low resistance on state (VCNR state) and a high resistance off state alternately appear. These anomalies are tentatively assumed as being due to reversible charge storage at the polypyrrole sites in the insulator layer.
Energy extraction measurements of an electron beam pumped, high Kr concentration KrF laser at elevated temperatures
Authors: Salesky E. T. , Kimura W. D.
Published: July 2002

Energy extraction measurements are obtained with an electron beam pumped KrF laser for initial gas temperatures from 294 to 425 K. Gas mixtures investigated are 89.7% Ar/10% Kr/0.27% F2 at 1.23 amagats and 99.6% Kr/0.4% F2 at 0.81 amagats. These densities correspond to equivalent electron stopping powers and result in an average pump rate of ≊120 kW/cm3. Measured efficiencies do not increase significantly with temperature, in sharp contrast to earlier predictions. The Kr2F* fluorescence is monitored as a function of temperature, and lasing or nonlasing conditions. Although the Kr2F* fluorescence emission does decrease during lasing conditions indicating partial saturation of the molecule, the fluorescence also does not exhibit a strong temperature dependence. Computer simulations are in good agreement with the results when using an inverse square root temperature dependence for the Kr2F* formation.
Mode characteristics of grating-incorporated channeled-substrate-planar GaAlAs lasers
Authors: Suemune I. , Fujii H. , Yamanishi M.
Published: July 2002

A grating-incorporated channeled-substrate-planar (CSP) laser is proposed for the 0° phase-shift mode selection. The 180° phase-shift mode is suppressed by combining fine gratings with the loss outside the electrode region. Single longitudinal mode oscillations of well-defined index-guided 0° modes are demonstrated for the wide channel CSP lasers.
Si-Si pair diffusion and correlation in AlxGa1−xAs and GaAs
Authors: Gavrilovic P. , Gavrilovic J. , Meehan K. , Kaliski R. W. , Guido L. J. , Holonyak N. , Hess K. , Burnham R. D.
Published: July 2002

The Si impurity is diffused into GaAs at temperatures in the range 725≤T≤850 °C. Secondary ion mass spectrometry (SIMS) analysis is used to obtain the Si atom density in the Si-diffused layers. On the basis of the SIMS data and the observation of a distinct exciton peak in absorption for samples diffused at temperatures ≲775 °C, we argue that in the range nSi≲4×1018/cm3 the Si impurity diffused into GaAs is correlated and is incorporated as Si-Si nearest-neighbor pairs.
Fundamental lateral mode oscillation via gain tailoring in broad area semiconductor lasers
Authors: Lindsey Chris , Derry Pam , Yariv Amnon
Published: July 2002

We show that by employing gain tailoring in a broad area semiconductor laser we achieve fundamental lateral mode operation with a diffraction-limited single-lobed far-field pattern. We demonstrate a tailored gain broad area laser 60 μm wide which emits 450 mW per mirror into a stable, single-lobed far-field pattern 3 1/2° wide at 5.3 Ith.
Low loss 4He+ implanted LiNbO3 waveguide produced by transient annealing
Authors: Al-Chalabi S. A. M.
Published: July 2002

The fabrication of planar optical waveguides in LiNbO3 using 4He+ implantation requires the samples to be annealed in an oxygen flow after implantation to remove the damage from the guiding layer and to replace oxygen loss during implantation. This letter describes, for the first time, the use of transient thermal annealing to process LiNbO3, and the results show that with this short time anneal, the quality of these waveguides has improved significantly giving an attenuation of 0.2 dB/cm at 0.633 μm.
Infrared photorefractive passive phase conjugation with BaTiO3: Demonstrations with GaAlAs and 1.09-μm Ar+ lasers
Authors: Cronin-Golomb Mark , Lau Kam Y. , Yariv Amnon
Published: July 2002

We report photorefractive passive phase conjugation of GaAlAs laser radiation at 815–865 nm and Ar+ laser radiation at 1090 nm. A ring passive phase conjugate mirror was used with BaTiO3 as the real-time holographic gain medium. With GaAlAs lasers phase conjugate reflectivities of up to 16% uncorrected for Fresnel losses were recorded. Effects of the strong associated feedback to the laser and attempts at mode locking are described. At 1090 nm the reflectivity remains approximately the same, but with a significantly longer time constant.
Two-material junction as a thermoelastic source of surface acoustic waves
Authors: Tankovsky N. S. , Ivanov D. V. , Burov J. I.
Published: July 2002

In the present work the junction of two thermoelastically different materials stuck together has been used as a thermoelastic transducer of surface acoustic waves. A simplified theoretical analysis gives a criterion of convenience for the pair of materials to be used. The experiments carried out proved the efficiency of such a source of surface acoustic waves.
Room-temperature electron trapping in Al0.35Ga0.65As/GaAs modulation-doped field-effect transistors
Authors: Nathan Marshall I. , Mooney P. M. , Solomon P. M. , Wright S. L.
Published: July 2002

Transient measurements of drain current are made as the gate voltage is pulsed in Al0.35Ga0.65As/GaAs depletion mode modulation-doped field-effect transistors. Large nonexponential decays are observed in the switching characteristics. Evidence is given which shows that these transients are caused by the emptying and filling of deep donors in the Al0.35Ga0.65As.
Structure variation of the index of refraction of GaAs-AlAs superlattices and multiple quantum wells
Authors: Kahen K. B. , Leburton J. P.
Published: July 2002

We present for the first time a detailed calculation of the index of refraction of various GaAs-AlAs superlattices. The calculation is performed by using a hybrid approach which combines the k⋅p method with the pseudopotential technique. Appropriate quantization conditions account for the influence of the superstructures on the electronic properties of the systems. The results of our model are in very good agreement with the experimental data. In comparison with the index of refraction of the corresponding AlGaAs alloy, characterized by the same average mole fraction x̄ of Al, our results indicate that the superlattice index of refraction values attain maxima at the various quantized transition energies. For certain structures the difference can be as large as ∼2%. These results suggest that the waveguiding and dispersion relation properties of optoelectronic devices can be tailored to design for specific optical application by an appropriate choice of the superlattice structure parameters.
Doping superlattices in organometallic vapor phase epitaxial InP
Authors: Yuan J. S. , Gal M. , Taylor P. C. , Stringfellow G. B.
Published: July 2002

Doping superlattices (nipi structures) have been grown in InP using organometallic vapor phase epitaxy in an atmospheric pressure reactor using trimethylindium and phosphine in a hydrogen ambient. The n-type and p-type dopants were diethyltellurium and dimethylzinc, respectively. The 4-K photoluminescence spectra at various excitation intensities are presented for a structure consisting of six 200-Å layers with doping levels of 1×1018 and 2×1018 cm−3 for the n and p layers. The luminescence peak is found to occur at energies considerably less than the band gap of InP and to move to higher energies with increased excitation intensity, as expected for doping superlattices where the band gap, which is indirect in real space, increases with increasing excited carrier concentration. The total photoluminescence signal decays in several steps, each exponential, with time constants ranging from 6×10−8 to 7×10−4 s at 4 K, typical of these spatially indirect band-gap materials.
Low-energy hydrogen ion implantation in Schottky barrier control
Authors: Singh R. , Ashok S.
Published: July 2002

The use of a shallow dopant implant at the semiconductor surface is a well entrenched technique for Schottky barrier height modification. The essential thermal annealing step following implantation has the undesirable effect of redistributing the dopant atoms and thus reducing the efficacy of barrier height control. It is shown here that a low-energy (∼0.4 keV) hydrogen ion implant in silicon following the dopant implant lowers the necessary annealing temperature from about 850 to less than 600 °C. The role of atomic hydrogen is believed to be twofold: passivation of dopant ion beam induced damage in Si as well as activation of dopant atoms by enabling a low-temperature solid phase epitaxial regrowth.
Modal properties of unstable resonator semiconductor lasers with a lateral waveguide
Authors: Salzman J. , Lang R. , Venkatesan T. , Mittlestein M. , Yariv A.
Published: July 2002

The modal properties of unstable resonator lasers with a lateral waveguide have been analyzed, and an unstable resonator semiconductor laser with a real index lateral waveguide has been demonstrated. Output powers in excess of 400 mW were observed with a stable, highly coherent lateral field distribution. The incorporation of a lateral real index waveguide with the unstable resonator configuration results in an increase in the external quantum efficiency and the appearance of ripples in the lateral field distribution.
Acoustic microscopy in air at 2 MHz
Authors: Fox J. D. , Kino G. S. , Khuri-Yakub B. T.
Published: July 2002

A reflection acoustic microscope system that operates directly in air at standard atmospheric pressure is described. The system utilizes a focused acoustic transducer operating at 2 MHz and the associated electronic system measures both the phase and amplitude of the reflected air signal. The transverse resolution of the imaging system is 400 μm, while the phase-based vertical resolution is approximately 0.6 μm. Applications of this air microscope to noncontacting surface profiling and film thickness measurements are presented.
Viscosity and steady shocks
Authors: Moss William C.
Published: July 2002

The dependence of the strain rate on the Hugoniot stress and the effective viscosity is derived for steady wave propagation, by considering the balance between viscous and driving forces in the steady wave. The strain rate in elastic-plastic solids is shown to vary as the fourth power of the Hugoniot stress, which is in agreement with experimental data.
Improvements in the modulation amplitude of submicron gratings produced in n-InP by direct photoelectrochemical etching
Authors: Lum R. M. , Ostermayer F. W. , Kohl P. A. , Glass A. M. , Ballman A. A.
Published: July 2002

The modulation amplitude of gratings produced by maskless etching techniques decreases rapidly at spatial frequencies >500 mm−1. This has limited the usefulness of these techniques for producing the submicron gratings required for distributed feedback lasers. We report improvements as large as a factor of 100 in the direct photoelectrochemical (PEC) etching of gratings in n-InP which were accomplished by changing the composition and concentration of the electrolyte solutions. Measurements on the PEC etching characteristics of n-InP in HF, HCl, HBr, and H2SO4 solvents are presented.
Metalorganic growth of epitaxial films of CdTe and HgCdTe on sapphire substrates
Authors: Hoke W. E. , Traczewski R. , Kreismanis V. G. , Korenstein R. , Lemonias P. J.
Published: July 2002

Specular epitaxial films of CdTe have been grown on (0001) sapphire substrates by the metalorganic chemical vapor deposition technique. The films grow with the (111)A orientation and exhibit narrow x-ray linewidths. Secondary ion mass spectrometry profiles indicate negligible diffusion of aluminum from the substrates. Epitaxial films of HgCdTe have been grown on top of the CdTe layers. Initial Hall measurements are encouraging for an all metalorganic chemical vapor deposition process for depositing HgCdTe on sapphire substrates.
Dependence of threshold current on the number of wells in AlGaAs-GaAs quantum well lasers
Authors: Blood P. , Fletcher E. D. , Woodbridge K.
Published: July 2002

GaAs-AlGaAs multiple quantum well injection lasers have been grown by molecular beam epitaxy with different numbers (N) of uncoupled GaAs wells 25 Å wide symmetrically disposed about the center of a 4000-Å-wide waveguide. The devices emit at about 770 nm and for N=4 the broad area threshold current density is 1.1 kA cm−2. The threshold current increases with increasing N (2<N<40) and this can be accounted for by changes in the optical confinement factor and the active ‘‘volume,’’ which implies that changes in capture probability with N in this structure are small.
Lateral coupled cavity semiconductor laser
Authors: Salzman J. , Lang R. , Yariv A.
Published: July 2002

We report the fabrication and operation of a lateral coupled cavity semiconductor laser that consists of two phase-locked parallel lasers of different lengths and with separate electrical contacts. Mode selectivity that results from the interaction between the two supermodes is investigated experimentally. Frequency selectivity and tunability are obtained by controlling the current to each laser separately. Highly stable single mode operation is also demonstrated.
GaAs sawtooth superlattice laser emitting at wavelengths λ>0.9 μm
Authors: Schubert E. F. , Fischer A. , Horikoshi Y. , Ploog K.
Published: July 2002

A new type of semiconductor superlattice laser grown by molecular beam epitaxy is realized in GaAs. The active region of the injection laser consists of alternating n and p Dirac-delta doped layers resulting in a sawtooth-shaped conduction-band and valence-band edge. The band gap of this new GaAs superlattice is smaller than the GaAs bulk band gap. Room-temperature operation of broad-area GaAs sawtooth superlattice (STS) injection lasers is demonstrated at a wavelength of 905 nm. The threshold current density of the STS laser is 2.2 kA/cm2.
Effect of pressure on the solid phase epitaxial regrowth rate of Si
Authors: Nygren Eric , Aziz Michael J. , Turnbull David , Poate John M. , Jacobson Dale C. , Hull Robert
Published: July 2002

The hydrostatic pressure dependence of the solid phase epitaxial growth rate of 〈100〉 Si into ion implanted amorphous Si at 500 °C has been monitored by Rutherford backscattering and channeling techniques. The growth rate increases with pressure so that at 20 kbar it is 14 times the ambient value. The increase is described by an activation volume for the process of −8.7 cm3/mole.
New model of the rapid initial oxidation of silicon
Authors: Schafer S. A. , Lyon S. A.
Published: July 2002

We propose a new model to explain the high initial oxidation rates observed during thermal oxidation of Si in dry O2. We show how the accumulation of fixed positive charge that develops in the SiO2 during thermal oxidation acts to reduce the concentration of holes at the Si-SiO2 interface and thereby reduces the density of broken Si–Si bonds there. It is believed that the density of broken Si bonds is a controlling factor in the oxide growth rate during the early phase of the oxidation process, when the rate is limited by the interfacial reaction mechanism. We also present experimental evidence that is consistent with the model, and is in good agreement with independent observations of the fixed oxide charge.
Electroreflectance of GaAs-AlGaAs modulation-doped field-effect transistors
Authors: Höpfel R. A. , Shah J. , Gossard A. C. , Wiegmann W.
Published: July 2002

We report the measurements of changes in the reflectivity spectrum of GaAs-AlGaAs modulation-doped field-effect transistors near the band gaps of both materials when a gate voltage is applied to vary the charge density at the interface. The observed changes (up to 0.3% at the band edge of AlGaAs) are attributed to the high external fields (∼105 V/cm) which modulate the already existing band bending, leading to changes in the band-edge absorption due to Franz–Keldysh effects in the quantum-confined structures. The possibility of using the effect for optical readout of transistor action is discussed.
Wide gap II-VI superlattices of ZnSe-Zn1−xMnxSe
Authors: Kolodziejski L. A. , Gunshor R. L. , Bonsett T. C. , Venkatasubramanian R. , Datta S. , Bylsma R. B. , Becker W. M. , Otsuka N.
Published: July 2002

In this letter we report the first growth of wide gap II-VI semiconductor superlattices of Zn1−xMnxSe (0<x<0.51). The superlattices are grown by molecular beam epitaxy. Bulk crystals of Zn1−xMnxSe (0<x<0.57) grown in the past have shown a predominance of the zincblende phase only up to x=0.3; above this mole fraction a predominance of the hexagonal phase is observed. For the superlattices and epilayers reported here, only the zincblende phase (100) is present over the entire composition range investigated. Transmission electron microscopy shows clear evidence of the superlattice structure. Photoluminescence measurements of ZnSe epilayers show a dominant free-exciton feature while the Zn1−xMnxSe epilayers exhibit two distinct photoluminescence peaks. The relative intensities of band-to-band transitions and Mn-related transitions are somewhat comparable for the epilayers. However, the superlattices having ZnSe in the wells show virtually no Mn-related emission regardless of the mole fraction of Mn in the barrier layers indicating significant carrier confinement. The intensity of the band-to-band emission is two orders of magnitude more intense for the superlattices than the ZnSe epilayer at 6.5 K. The superlattices show a red shift of the photoluminescence peak which can be explained in terms of shifts in the band gaps due to the presence of strains.
Low threshold planar buried heterostructure lasers fabricated by impurity-induced disordering
Authors: Thornton R. L. , Burnham R. D. , Paoli T. L. , Holonyak N. , Deppe D. G.
Published: July 2002

We report on the fabrication of index-guided buried heterostructure lasers by the process of silicon impurity-induced disordering. This fabrication process for a buried heterostructure laser offers the advantage of reduced fabrication complexity over previous fabrication methods. We present measurements that demonstrate the operation of these devices in a single longitudinal mode, fundamental transverse mode, and with cw threshold currents as low as 3 mA. We also have extracted 80 mW cw from a device with a 10-mA threshold current. Our results indicate that this process has great potential for the fabrication of low threshold, efficient light sources.
Nonlinear thin-film guided waves in non-Kerr media
Authors: Stegeman G. I. , Ariyasu J. , Seaton C. T. , Shen T. P. , Moloney J. V.
Published: July 2002

The power-dependent wave vector is calculated for nonlinear waves guided by a thin film bounded by media whose dielectric constant varies as some arbitrary power of the optical field or saturates at high powers. The effect of such non-Kerr-like nonlinearities on the power-dependent wave vector and field distributions is given for a number of potential devices proposed earlier for Kerr-like media.
Spectral analysis of ion-acoustic soliton excitation
Authors: Chang Hong-Young , Lien Chuong , Sukarto Sudewo , Hill Jacqueline , Raychaudhuri Santwana , Lonngren Karl E.
Published: July 2002

The evolution of the frequency spectrum of a velocity modulated burst of ions from a fine mesh grid in a plasma is measured and interpreted. Initial frequency modulation close to the grid indicates a ‘‘klystron bunching’’ of the ions. The measured spectrum far from the grid indicates the excitation of an ion-acoustic soliton.
Observation of fractional neutralization of slow multicharged ions by impact on a metal surface
Authors: Hughes R. H. , Pederson D. O. , Ye X. M.
Published: July 2002

We report the first observation of energy losses and fractional neutralization of slow multicharged ions incident on a metal surface. Data were obtained on 374 eV per charge aluminum 3≤z≤6 ions incident on an uncharacterized gold surface at a grazing angle of 7° and scattered through 14°. The resulting atoms consisted of about 60% neutral and 40% singly charged ions in the case of incident z=4 ions. The scattering process did not appreciably broaden the ion linewidths. The apparatus makes use of a laser generated heavy ion source.
Growth of Hg1−xZnxTe by molecular beam epitaxy on a GaAs(100) substrate
Authors: Sivananthan S. , Chu X. , Boukerche M. , Faurie J. P.
Published: July 2002

We report for the first time the growth and characterization of n-type and p-type Hg1−xZnxTe layers grown by molecular beam epitaxy on GaAs (100) substrates. The HgZnTe grown over either (111)CdTe‖‖(100)GaAs or (100)CdTe‖‖(100)GaAs buffer layers preserved the orientation of the buffer. Electron diffraction and electrical characterization demonstrate the HgZnTe layers to be comparable to high quality HgCdTe of the same cut-off frequency. Since the layers exhibit cut-off wavelengths in far and mid-infrared range and are of high quality, they appear to be candidates for infrared devices.
Microwave amplification to 2.5 GHz in a quantum state transfer device
Authors: Pond J. M. , Kirchoefer S. W. , Cukauskas E. J.
Published: July 2002

Reflection amplification has been demonstrated from 40 MHz to 2.5 GHz using a bilevel superlattice structure known as a quantum state transfer device. Measurements of the magnitude and phase of the voltage reflection coefficient were made at 300 K using a specialized microwave probe. The maximum normalized gain, at 40 MHz, approaches the gain expected from dc measurements of the negative differential resistance.
Study of high electrical field induced degradation of channel response in metal-oxide-semiconductor field-effect transistors using an ac conductance technique
Authors: Chow P. D. , Wang K. L.
Published: July 2002

ac conductance (G) measurements in the frequency domain are used to monitor the degradation of the inversion layer response in metal-oxide-semiconductor field-effect transistors (MOSFET’s) due to high field stressing. The admittance of the conduction channel of the MOSFET’s is analyzed by use of a transmission line model. The time constant which governs the frequency response of the MOSFET inverted channel is extracted from the peak of the G/ω vs ω curve and is shown to be an important and sensitive parameter for studying the degradation of MOSFET interface properties after high field stressing. Measured data on 9 and 35 nm gate oxide MOSFET’s showed that the channel response degradation by high field stressing depends strongly on the gate oxide thickness.
Grown-in defects in multi-epilayer GaAs grown by metalorganic chemical vapor deposition under different growth conditions
Authors: Li Sheng S. , Lee D. H. , Choi C. G. , Andrews J. E.
Published: July 2002

Studies of the grown-in defects in multi-epilayer GaAs (with/without a buffer layer) grown by metalorganic chemical vapor deposition under different [AsH3]/[TMGa] ratios, growth temperatures, and growth rates have been made in this letter by the deep level transient spectroscopy method. For samples without a buffer layer, two electron traps with activation energies of Ec−0.83 eV (EL2a) and Ec−0.74 eV are observed, whereas for samples with 6-μm-thick buffer layers, only EL2a level is found. The concentration of the deep level traps is found closely related to the [AsH3]/[TMGa] ratio, the growth temperature, and the growth rate (mainly at lower growth rate). The results show that, for samples without a buffer layer, the background dopant density profile is closely related to the deep level trap density profile in the epilayers, whereas for samples with a buffer layer, the profile of background dopant density is less influenced by the presence of the deep level trap.
Deep level in some perovskite oxides as gas sensor materials
Authors: Arakawa Tsuyoshi , Kurachi Hiroshi , Shiokawa Jiro
Published: July 2002

Deep level in some perovskite oxides ( p type) has been studied by deep level transient spectroscopy (DLTS). One deep hole trap is present in every perovskite oxide. In SmMO3 (M=Cr, Mn, Co) hole traps with activation energy of 0.14 eV for SmCoO3, 0.31 eV for SmMnO3, and 0.22 eV for SmCrO3 were detected, respectively. The DLTS signal disappeared after the treatment in dilute hydrogen at elevated temperatures. The activation energy for a trap level was shown to be close to that derived from the conductivity measurement.
Neutral carbon-related complex defects and the annealing of thermal donors in p-type Czochralski silicon
Authors: Weman H. , Monemar B. , Holtz P. O.
Published: July 2002

The influence of different consecutive annealing cycles on the formation of thermal donors and related neutral (isoelectronic) complex defect in p-type B-doped Czochralski Si has been studied by a combination of photoluminescence, infrared transmission, and electrical measurements. It is concluded that the 767 meV neutral defect is closely related to thermal donors (TD’s), and is probably created from such complexes by the reaction of one C atom with the virgin complex TD’s, neutralizing the TD core. Both the TD’s and the 767 meV defects disappear upon a second annealing at 650 °C. If another subsequent annealing cycle at 450 °C is attempted, TD’s are formed, but not the 767 meV neutral defects.
Vibration resistance, short coherence length operation, and mode-locked pumping in passive phase conjugate mirrors
Authors: Cronin-Golomb Mark , Paslaski Joel , Yariv Amnon
Published: July 2002

Because the ring and semilinear passive phase conjugate mirrors use dynamic transmission holograms, they are insensitive to vibration and may be pumped with light of short coherence length or with picosecond mode-locked laser light. Experimental demonstrations of these modes of operation are described.
Low loss, wavelength tunable, waveguide electro-optic polarization controller for λ=1.32 μm
Authors: Alferness R. C. , Buhl L. L.
Published: July 2002

We propose and demonstrate a new low loss Ti:LiNbO3 waveguide electro-optic polarization controller for λ=1.32 μm. The device provides general polarization transformations, is wavelength tunable, and has a total fiber device fiber insertion loss of 2.2 dB.
Optically pumped laser oscillation at 3.82 μm from InAs1−xSbx grown by molecular beam epitaxy on GaSb
Authors: van der Ziel J. P. , Chiu T. H. , Tsang W. T.
Published: July 2002

Molecular beam epitaxy has been used to grow InAs1−xSbx active layers on GaSb substrates. Lattice matches of better than 10−3 were obtained with x≂0.09. Index waveguiding of the relatively low refractive index InAs1−xSbx is obtained by using an adjacent GaSb guiding layer and a lower refractive index Al0.5Ga0.5Sb cladding layer. Optically pumped laser emission at 3.82 μm has been observed from 77 to 135 K with a T0=15.9 K.
Picosecond nonlinear absorption and four-wave mixing in GaInAsP
Authors: Islam M. N. , Ippen E. P. , Burkhardt E. G. , Bridges T. J.
Published: July 2002

We report the first λ∼1.5 μm picosecond near-band-gap nonlinear absorption and degenerate four-wave mixing (DFWM) experiments in room-temperature GaInAsP using a mode-locked color center laser. The temporal, spectral, and pump energy dependences of the nonlinear signals are investigated. Nonlinear absorption cross sections σeh as large as −5.7×10−15 cm2 are obtained from the pump probe results, while effective nonlinear cross sections σeff as large as 7.8×10−16 cm2 (corresponding to a steady ‖χ(3)‖∼3.8×10−3 esu for a 20-ns relaxation time) are measured in the DFWM experiments.
Germanium film on SiO2 with a 〈100〉 texture deposited by the rf sputtering technique
Authors: Egami Koji , Ogura Atsushi
Published: July 2002

Germanium (Ge) films on SiO2 with 〈100〉 texture deposited by a sputtering technique and the texture enhancement by a subsequent solid-state thermal annealing are demonstrated for the first time. A 0.6-μm-thick Ge film on a surface oxidized Si wafer deposited by the rf sputtering technique at 600 °C produces a 〈100〉 texture, and the preferential orientation of the film is enhanced by a conventional grain growth process at 900 °C (approximately 0.95Tm, where Tm is the melting point in the Kelvin scale) for 1 h, while the crystallographic texture of the films has never changed at 650 °C (0.75Tm) annealing. The texture enhancement is interpreted by the existence of 〈100〉 oriented precursors and a simple coalescence and rearrangement model.
Surface morphology of epitaxial CaF2 films on GaAs(100)
Authors: Hoffman R. A. , Sinharoy S. , Farrow R. F. C.
Published: July 2002

The surface morphology of CaF2 films grown epitaxially on (100) GaAs substrates in an ultrahigh vacuum system is examined using reflection high-energy electron diffraction, scanning electron microscopy, and replica transmission electron microscopy. Proper substrate surface preparation and film deposition techniques are critical for obtaining epitaxial films which are crack free and smooth. We have demonstrated that group II-A fluoride films which have a barely perceptible surface texture can be grown onto (100) oriented substrates.
Electro-optic sampling of planar digital GaAs integrated circuits
Authors: Freeman J. L. , Diamond S. K. , Fong H. , Bloom D. M.
Published: July 2002

We report a new electro-optic sampling configuration which allows planar digital GaAs circuits to be probed noninvasively. Our technique employs a novel backside reflecting geometry, in which a laser beam enters the GaAs substrate from the back and reflects from the circuit metallization. By combining the electro-optic effect in GaAs with sub-band-gap (1.06 μm) picosecond pulses from a continuous wave, mode-locked neodymium:yttrium aluminum garnet laser, we are able to make wide-band voltage measurements within GaAs integrated circuits. Results are presented of signals measured on the 2-μm-wide on-chip output line of a medium scale integrated multiplexer/demultiplexer clocked at 2.6 GHz.
N
p
n
N double-heterojunction bipolar transistor on InGaAsP/InP
Authors: Su L. M. , Grote N. , Kaumanns R. , Schroeter H.
Published: July 2002

Double-heterojunction bipolar transistors have been fabricated on InGaAs(P)/InP with current gains of up to 200. Transistors with a p+-InGaAs/N-InP base/collector junction exhibited drastic gain reduction at low collector bias voltages which is ascribed to the electron repelling effect of the conduction-band spike formed at the collector heterojunction. To overcome this complication a thin n-InGaAs transition layer was inserted between the ternary base and the InP wide-gap collector. The resulting nN double-layer collector structure leads to excellent current/voltage characteristics.
Dependence of radiation-induced interface traps on gate electrode material in metal/SiO2/Si devices
Authors: Zekeriya Viktor , Ma T-P.
Published: July 2002

The density of radiation-induced interface traps in a metal-oxide-semiconductor (MOS) device has been found to depend on the electrode material used to form the gate. For a given oxide process, this dependence correlates well with the gate-induced interfacial stress distribution in the MOS system. The gate-induced bond strain gradient model that we proposed previously may be readily used to explain the results.
Schottky barrier diodes using thick, well-characterized boron phosphide wafers
Authors: Kumashiro Y. , Okada Y.
Published: July 2002

Thick, single crystalline boron phosphide (BP) wafers (∼200–300 μm) grown by the chemical vapor deposition technique were characterized by the measurements of lattice constants by the Bond method and electrical properties by the Van der Pauw method. Two types of Schottky barrier diodes, i.e., n-BP-Sb and p-BP-Au, were fabricated. The n-BP-Sb diode has the highest reverse voltage of 5 V and a barrier height of 1.4 eV, while those of the p-BP-Au diode are 1 V and 1.2 eV. These results suggest that device application of BP is promising.
Elastic behavior of polycrystalline Nb3Sn at low temperatures
Authors: Poirier M. , Laroche F. , Martin M. , Bussière J. F.
Published: July 2002

The elastic constants of polycrystalline Nb3Sn were determined as a function of temperature when the samples were submitted to uniaxial tensile stress. The Young’s (E) and shear (G) moduli were obtained from an ultrasonic pulse transmission technique in the range 4–300 K. Their behavior with temperature and applied stress is discussed in terms of the martensitic phase transformation occurring at ∼43 K and the ferroelastic character of the tetragonal phase (T <43 K). Uniaxial tensile stress is found to stiffen the moduli at all temperatures by stabilizing the crystal structure and by progressively eliminating the domains in the tetragonal phase.
Microsecond duration optical pulses from a UV-preionized XeCl laser
Authors: Taylor R. S. , Leopold K. E.
Published: July 2002

XeCl laser pulse durations of 1.5 μs (full width at half-maximum) have been obtained using a recently developed UV-preionized magnetically induced pulser laser excitation scheme.
Treatment of broadening in Monte Carlo calculations of quantum transport
Authors: Lin J. , Chiu L. C.
Published: July 2002

By employing a simple two-level system, it is shown that modification of the traditional Monte Carlo technique is necessary for solving the transport equation when quantum mechanical broadening is included. In Monte Carlo calculations, inclusion of broadening may lead to unphysical and catastrophic energy runaway if the quantum mechanical correlation energy is not properly accounted for.
Neutral impurity scattering in AlGaAs
Authors: Drummond T. J. , Hjalmarson H. P.
Published: July 2002

In the alloy system AlGaAs, a crossover from a direct (Γ) to an indirect (X) conduction-band minimum occurs when the AlAs mole fraction approaches 0.45. For AlAs mole fractions greater than about 0.2, the ground-state energy of substitutional donors becomes deep relative to the direct minimum. The donor level achieves a maximum depth of 0.16 eV near the crossover and it is not uncommon to find the donor impurity concentration exceeding the free-electron concentration by a factor of 10 at room temperature and a factor of 20 at lower temperatures. For large impurity to electron ratios and doping levels on the order of 1018/cm3, neutral impurity scattering proves to be the dominant scattering mechanism at all temperatures.
New semi-insulating InP: Titanium midgap donors
Authors: Brandt C. D. , Hennel A. M. , Pawlowicz L. M. , Wu Y.-T. , Bryśkiewicz T. , Lagowski J. , Gatos H. C.
Published: July 2002

Deep levels due to titanium were identified for the first time in InP and GaAs employing capacitance transients and optical absorption measurements. They were found to be Ti4+/Ti3+ donor levels at energies of 0.63±0.03 eV and 1.00±0.03 eV in InP and GaAs, respectively. The near midgap location of this donor level in InP is technologically very significant, since it provides a new means for obtaining semi-insulating InP with a resistivity of about 107 Ω cm. The thermal stability of Ti-doped InP should be superior to that of Fe-doped InP. A formulation involving the Ti dopant and shallow acceptor impurities for obtaining semi-insulating InP from the melt is presented.
A simple method for computing the relativistic Compton scattering kernel for radiative transfer
Authors: Prasad Manoj K. , Kershaw David S. , Beason J. Douglas
Published: July 2002

The Klein–Nishina differential cross section averaged over a relativistic Maxwellian electron distribution is analytically reduced to a single integral, which can then be rapidly evaluated in a variety of ways. This is, to our knowledge, the first correct computation of the Compton scattering kernel.
Surface-limited release of deuterium from iron and the effect of surface oxygen
Authors: Wampler W. R.
Published: July 2002

The surface-limited release of deuterium from solution in polycrystalline iron was measured in ultrahigh vacuum using nuclear reaction analysis and ion implantation with surface characterization by Auger electron spectroscopy. For a bare iron surface the magnitude and temperature dependence of the release rate are quantitatively predicted by a model in which the rate limiting step is the recombination and desorption of deuterium chemisorbed on the surface. The release rate decreased approximately linearly with oxygen coverage up to a cutoff at about 0.4 monolayer.
Experimental study of the frequency limits of a resonant tunneling oscillator
Authors: Coleman Paul D. , Goedeke Steven , Shewchuk Thomas J. , Chapin Peter C. , Gering Joseph M. , Morkoç Hadis
Published: July 2002

An equivalent circuit obtained from microwave impedance and power data is proposed for a resonant tunneling diode. The four-element circuit consists of a series R and C in parallel with a nonlinear negative differential conductance −G, the combination in turn in series with a resistor r. The resistive cut-off frequency predicted by this model depends on both the RC and RG products. Detection at THz frequencies is also explained by the model.
Femtojoule optical switching in nonlinear semiconductor laser amplifiers
Authors: Sharfin W. F. , Dagenais M.
Published: July 2002

We have demonstrated the operation of an optical switch requiring less than 1 f J (<7000 photons) of incident optical energy. The switch operates at room temperature, is compatible with optical communication systems, and is cascadable because it has gain. The switching times (on and off) are determined to be less than 1 ns. This device significantly advances the possibility for realization of high throughput optical signal processing and digital optical computing.
Phase insensitive detection of laser-generated ultrasound
Authors: Hutchins D. A. , Page J. H.
Published: July 2002

An acoustic source formed by pulsed laser irradiation has been used to investigate the piezoelectric and acoustoelectric effects within a cadmium sulphide detector. Analysis of detected waveforms has enabled the two effects to be identified. The resulting transducer combination has application to imaging systems, where phase insensitivity may be required.
Stacking faults in WSi2: Resistivity effects
Authors: d’Heurle F. M. , LeGoues F. K. , Joshi R. , Suni Ilka
Published: July 2002

Films of WSi2 initially deposited in an amorphous form have been known to display an unexpected resistivity maximum when annealed at a temperature corresponding to the transition from the low-temperature hexagonal structure to the high-temperature tetragonal structure. It is shown that the resistivity maximum is due to an extremely high (5×106/cm) density of stacking faults. Thus, at least one of the scattering defects which contribute to the relatively high resistivity of WSi2 films has been identified.
Variable barrier height semiconductor/HxWO3 diodes
Authors: Rauh R. D. , Rose T. L. , Benoit S. N.
Published: July 2002

Diodes of configuration HxWO3‖p- or n-Si and HxWO3‖n-CdS have been fabricated, where the effective work function of the HxWO3 can be varied reversibly by electrochemical hydrogen insertion/extraction. The diodes have a continuously variable barrier height, as indicated by their saturation photovoltage. These systems serve as prototypes for a class of chemically sensitive electronic devices.
Measurement of the minority-carrier lifetime and injection efficiency in AlGaAs/GaAs heterojunction bipolar transistors
Authors: Chand Naresh , Fischer Russ , Henderson Tim , Morkoç Hadis , Neugroschel Arnost
Published: July 2002

To obtain an insight of the factors limiting the current gain, minority-carrier lifetime (τn), base transport factor (αT), and emitter injection efficiency (γ) have been studied in npn AlGaAs/GaAs heterojunction bipolar transistors using a base width modulation technique. It is found that in addition to γ, αT is also a function of current injection level. At low injection αT increases at a fast rate with increasing injection. It is felt that, in addition to the surface recombination current at the periphery of the emitter-base space-charge region which affects γ, surface recombination of the minority carriers in the base of a mesa device is also important as it greatly reduces αT and hence the current gain.
Reduction of the spectral linewidth of semiconductor lasers with quantum wire effects—Spectral properties of GaAlAs double heterostructure lasers in high magnetic fields
Authors: Arakawa Y. , Vahala K. , Yariv A. , Lau K.
Published: July 2002

The spectral linewidth of a GaAlAs double heterostructure laser placed in a high magnetic field is measured at 190 K. It is found that the power-dependent spectral linewidth is reduced by a factor of 0.6 in a magnetic field of 19 T. This reduction is believed to result mainly from the reduction of the linewidth enhancement factor α due to a quasi-one-dimensional electronic system formed by the high magnetic field (i.e., by quantum wire effects).
Picosecond transient grating studies of polymeric thin films
Authors: Rao D. Narayana , Burzynski Ryszard , Mi Xin , Prasad Paras N.
Published: July 2002

Picosecond transient grating experiments have been performed on a 5-μm-thick polystyrene film doped with naphthalene and on a 700-μm-thick pure polystyrene film at room temperature. In both cases, the observed acoustic modulation of the diffracted signal is explained by the formation of a thermal grating. No detectable acoustic attenuation is observed within the time delay of 6 ns, and the speed of sound obtained from the acoustic modulation period is in excellent agreement with that reported by an ultrasonic measurement. The coherent third order nonlinear electronic response observed at zero-time delay is found to be shorter than 2 ps.
Self-aligned contact process for Nb/Al-AlOx/Nb Josephson junctions
Authors: Morohashi Shin’ichi , Hasuo Shinya , Yamaoka Toyoshi
Published: July 2002

High quality Nb/Al-AlOx/Nb Josephson junctions have been fabricated by a novel process named the self-aligned contact process. After the definition of the junction area by a reactive ion etching (RIE) technique, the exposed Nb layer and the junction edge are anodized to protect against electrical shorts and an Al film is deposited as the etching stopper layer. After base electrode patterning by RIE, an insulation layer is deposited. The contact hole, with the diameter of the junction, for connecting a counter electrode and a wiring layer, can be made without registration because of the deposited Al film. The junctions fabricated by this process have exhibited excellent current-voltage characteristics (Vm =70 mV at the critical current density  jJ =1.8 kA/cm2, Vm =11 mV at  jJ =20 kA/cm2).