bluuebunny/crossref_metadata_2025 huggingface dataset:
Al0.3Ga0.7As/GaAs single quantum well structures grown by molecular beam epitaxy on misoriented substrates
Authors: Tsui R. K. , Kramer G. D. , Curless J. A. , Peffley M. S.
Published: July 2002

In many instances the intrinsic photoluminescence at low temperatures of (Al,Ga)As/GaAs single quantum well structures grown by molecular beam epitaxy is weak and broad, unlike the case for most multiple quantum well structures. This is believed to be due to the microscopic roughness of the first GaAs-on-top-of-(Al,Ga)As interface. By using substrates misoriented appropriately from nominal (100) such that Al0.3Ga0.7As barrier layers with smooth surface morphology could be obtained at a growth temperature of 650 °C, we have grown structures with a single 100-Å-wide GaAs well. The structures grown on misoriented substrates showed stronger and sharper (as narrow as 1.8 meV) intrinsic emission peaks at 4.2 K. The improvement is believed to be due to the growth of smoother interfaces.
Stability of nonlinear stationary waves guided by a thin film bounded by nonlinear media
Authors: Moloney J. V. , Ariyasu J. , Seaton C. T. , Stegeman G. I.
Published: July 2002

The stability of stationary, TE0-type, nonlinear, thin-film guided waves was investigated numerically for both symmetric and asymmetric planar waveguides with nonlinear cladding and substrate layers. It is found that large regions of the dispersion curves are unstable at high powers.
Thermal detection of electron spin resonance in the persistent photoconductive state of semi-insulating GaAs crystals grown from pyrolytic BN crucibles
Authors: Blazey K. W. , Schneider J.
Published: July 2002

Thermally detected electron spin resonance (TDESR) has been applied to paramagnetic defects characteristic of semi-insulating (SI) GaAs crystals grown from pyrolytic boron nitride (pBN) crucibles. A strong isotropic TDESR signal near g=2.2 and two anisotropic lines at higher fields were observed at T=4.2 K and 13 GHz after in situ optical excitation. Spin-dependent scattering of electrons, in their persistent photoconducting state, by paramagnetic defects is discussed as a possible cause of these resonances. Unsuccessful searches for this TDESR signal in semi-insulating GaAs crystals grown under non-pBN ambient conditions point to paramagnetic defects owing to the inclusion of some crucible material, e.g., nitrogen, as the source of the TDESR spectrum in pBN-GaAs.
New method for separating and characterizing interface states and oxide traps on oxidized silicon
Authors: Sah Chih-Tang , Lin Wallace Wan-Li , Pan Samuel Cheng-Sheng , Hsu Charles Ching-Hsiang
Published: July 2002

The generation-annealing kinetics of interface and oxide traps are separated using a new time-dependent high-frequency capacitance-voltage technique based on the independence of the trapped oxide charge density on the silicon surface energy band bending or surface potential. An application example of this new technique is described which gives the post-irradiation room-temperature annealing rates and annealed densities of the two oxide and two interface traps generated by an 8-keV electron beam.
Threshold adjustments for complementary metal-oxide-semiconductor optimization using B and As focused ion beams
Authors: Lee J. Y. , Kubena R. L.
Published: July 2002

Threshold adjustments have been performed on n- and p-channel metal-oxide-semiconductor (mos) field-effect transistors for complementary metal-oxide-semiconductor circuits using B and As focused ion beams (FIB’s). After conventional flood ion implantation for the wells and channels, additional selective threshold adjustment implants were made by FIB’s in 1×1012/cm2 increments. The threshold voltage shifts were 65 and 100 mV per each 1×1012/cm2 of FIB dose for PMOS and NMOS devices, respectively. Based on these results, precise tailoring of threshold values for optimal circuit performance appears practical.
Magnetic properties of Fe-R-B powders
Authors: Gudimetta K. , Christodoulou C. N. , Hadjipanayis G. C.
Published: July 2002

The magnetic properties of Fe77R15B8 powders have been measured as a function of particle size in the temperature range 77–300 K. The coercivity is found to increase first with particle size to a maximum value and then to decrease again. This behavior is explained with the single domain particle theory. The peak values of coercivity obtained in the various alloys are found to scale with the anisotropy field. The temperature coefficients of coercivity are smaller than those observed in sintered magnets.
Effects of substrate preparation conditions on GaAs oval defects grown by molecular beam epitaxy
Authors: Fujiwara K. , Nishikawa Y. , Tokuda Y. , Nakayama T.
Published: July 2002

Effects of substrate preparation conditions, i.e., wet chemical and ultrahigh vacuum cleaning preparations, on GaAs oval defects grown by molecular beam epitaxy (MBE) were investigated. It is found that, with our MBE system, the presence of the smaller (<10 μm) ovally shaped defects without macroscopic core particulates can be ascribed to surface microscopic contaminations. Most of the other remaining larger (>10 μm) oval defects with core particulates observed on 1-μm-thick GaAs MBE layers are attributed to surface macroscopic contaminations. The total density is reduced to 300 cm−2 without significantly modifying the growth cell parameters.
Oxidation resistant sol-gel derived silicon oxynitride thin films
Authors: Brow Richard K. , Pantano Carlo G.
Published: July 2002

Silicon oxynitride films, made by reacting porous, sol-gel derived silicon dioxide with ammonia, were oxidized in dry O2 between 800 and 1000 °C. Film oxidation was characterized by ellipsometry and secondary ion mass spectrometry. Increasing the nitrogen content of the film increased oxidation resistance of the film.
Relationship between secondary defects and electrical activation in ion-implanted, rapidly annealed GaAs
Authors: Pearton S. J. , Hull R. , Jacobson D. C. , Poate J. M. , Williams J. S.
Published: July 2002

The removal of lattice damage and consequent activation by rapid thermal annealing of implanted Si, Se, Zn, and Be in GaAs was investigated by capacitance-voltage profiling, Hall measurements, transmission electron microscopy (TEM), secondary ion mass spectrometry, and Rutherford backscattering. The lighter species show optimum electrical characteristics at lower annealing temperatures (∼850 °C for Be, ∼950 °C for Si) than the heavier species (∼900 °C for Zn, ∼1000 °C for Se), consistent with the amount of lattice damage remaining after annealing. TEM reveals the formation of high densities (107 cm−2) of dislocation loops after 800 °C, 3 s anneals of high dose (1×1015 cm−2) implanted GaAs, which are gradually reduced in density after higher temperature anneals (∼1000 °C). The remaining loops do not appear to affect the electrical activation or carrier mobility in the implanted layer, the latter being comparable to bulk values.
Raman scattering study of disordering and alloying of GaAs-AlAs superlattice by As implantation and rapid thermal annealing
Authors: Kirillov D. , Ho P. , Davis G. A.
Published: July 2002

Disordering and alloying of the GaAs-AlAs superlattice by high-dose implantation of As ions and rapid thermal annealing were studied by Raman scattering. It was found that the superlattice was disordered by ion implantation, and the spectrum of the resulting amorphous phase was identical to the spectrum of amorphous AlxGa1−xAs alloy. It consisted of GaAs- and AlAs-type bands which had the same energies as corresponding bands in amorphous GaAs and AlAs. The ratio of intensities of the bands reflected the Al content. After annealing, the crystalline AlxGa1−xAs alloy was formed with composition dependent on actual thickness of the superlattice layers.
High-frequency amplification and generation in charge injection devices
Authors: Kastalsky A. , Abeles J. H. , Bhat R. , Chan W. K. , Koza M. A.
Published: July 2002

Room-temperature high-frequency measurements on a three-terminal amplifying device based on real-space hot-electron transfer between two conducting layers separated by a potential barrier have been performed. The devices grown by organometallic chemical vapor deposition utilize a novel undoped GaAs/AlGaAs heterostructure which, through its dramatically reduced parasitic leakage compared to previous structures, permits, for the first time, operation as a charge injection transistor. The charge injection transistor exhibits true three-terminal amplification due to real-space hot-electron transfer controlled by electron temperature in a high mobility channel. The device demonstrates power and current gains with cut-off frequencies of 9.8 and 29 GHz, respectively, with maximum current gain of 39 dB. In the negative resistance transistor mode, the same device was found capable of microwave generation up to 7.7 GHz. The frequency response of our device is shown to be limited by RC in the output circuit and methods for improvement of the cut-off frequency are discussed.
21% (one sun, air mass zero) 4 cm2 GaAs space solar cells
Authors: Werthen J. G. , Virshup G. F. , Ford C. W. , Lewis C. R. , Hamaker H. C.
Published: July 2002

GaAs space solar cells with areas of 4 cm2 have been fabricated by metalorganic chemical vapor deposition. The AlGaAs-GaAs heteroface structures have been grown in both the p-n and n-p configurations. Under one sun, air mass zero conditions and at 25 °C, the p-n cell is characterized by a short-circuit current density of 32.3 mA/cm2, an open-circuit voltage of 1.05 V, and a fill factor of 0.84, resulting in a conversion efficiency of 21.1%. The corresponding values for n-p cells are 33.8 mA/cm2, 1.01 V, and 0.83, resulting in a conversion efficiency of 21.0%.
Measurement of excited-state densities during high-current operation of a hydrogen thyratron using laser-induced fluorescence
Authors: Erwin D. A. , Gundersen M. A.
Published: July 2002

The population of the n=2 level of atomic hydrogen and the collisional relaxation rates of the n=3 and n=4 levels during the conductive phase in the positive column of a high-current ( J∼100–400 A/cm2) pulse in a hydrogen thyratron were measured. These results demonstrate laser-induced fluorescence to be a useful in situ diagnostic for high-current switch plasmas.
Growth of GaAs by switched laser metalorganic vapor phase epitaxy
Authors: Doi Atsutoshi , Aoyagi Yoshinobu , Namba Susumu
Published: July 2002

Crystal growth of GaAs by switched laser metalorganic vapor phase epitaxy (SL MOVPE) is reported. This growth technique is achieved by combining laser MOVPE and atomic layer epitaxy. The growth process in SL MOVPE can be explained by a model which assumes that trimethylgallium adsorbed on the crystal surface is decomposed in a photocatalytic reaction and that the decomposition rate depends on the surface species present on the substrate.
Low-temperature deposition of low resistivity ZnSe films by reactive sputtering
Authors: Stirn R. J. , Nouhi A.
Published: July 2002

Low resistivity semiconducting films of ZnSe have been deposited at temperatures as low as 120 °C using dc magnetron co-sputtering of Zn and In (dopant) targets in a reactive atmosphere of H2Se/Ar. Yellowish transparent films of ZnSe on glass and conductive transparent oxide-coated glass substrates were obtained having a room-temperature resistivity as low as 20 Ω cm. Atomic absorption analysis showed a Zn to Se ratio of 49.8:49.0 and In concentration of about 1% for the reactively sputter-deposited ZnSe:In films on glass. Optical absorption/transmission measurements yielded an energy band gap of about 2.65 eV at room temperature. X-ray diffraction results indicated highly oriented polycrystalline films on glass with the c axis parallel to the plane of the film.
Anomalous surface transformations in crystalline silicon induced by subpicosecond laser pulses
Authors: Kanemitsu Yoshihiko , Ishida Yuzo , Nakada Ichiroh , Kuroda Hiroto
Published: July 2002

Surface transformations in crystalline silicon are investigated, using 400 fs laser pulses, at intensities just above the melting threshold. Anomalous changes of surface heights are observed, and they are enhanced for shorter pulses. These experimental results are well understood with a picture that shock stress generated by the ultrashort pulse excitation causes anomalous surface transformations of crystalline silicon.
InGaAsP closely spaced dual wavelength laser
Authors: Dutta N. K. , Cella T. , Zilko J. L. , Ackerman D. A. , Piccirilli A. B. , Greene L. I.
Published: July 2002

The fabrication and performance characteristics of an independently controllable closely spaced dual wavelength laser structure are described. The laser structure utilizes semi-insulating (Fe-doped InP) layers both for confinement of the current to the active regions and for separation of the active regions of the two lasers. Both lasers emit in single frequencies near 1.55 μm by virtue of frequency selective feedback provided by a second order grating. The light coupled into a single mode fiber from both lasers is about 5 dB smaller than that for optimum coupling arrangement of each laser. Dual wavelength laser structures of this type are useful for wavelength multiplexed optical transmission systems.
Atomic structures at IrSi(IrGe)/Ir(001) interfaces
Authors: Liu H. F. , Liu H. M. , Tsong T. T.
Published: July 2002

The interface atomic structure of very thin IrSi(IrGe) films grown on the Ir(001) plane has been studied with the field ion microscope. Two distinctive types of structures have been observed. One shows the C(2×2) structure of the substrate. As the size of the layer is reduced by field evaporation, the surface relaxes into a rhombic structure resembling the (011) Ir layer of the IrSi(IrGe) crystal. The other shows a rectangular unit cell of a larger size, which is not yet successfully correlated to the structure of the IrSi(IrGe) crystal.
Low-temperature metalorganic growth of CdTe and HgTe films using ditertiarybutyltelluride
Authors: Hoke W. E. , Lemonias P. J.
Published: July 2002

Epitaxial films of CdTe and HgTe have been grown by metalorganic chemical vapor deposition using a new tellurium source, ditertiarybutyltelluride. This compound is demonstrated to be less stable than presently available organotellurium compounds which permits film growth at lower substrate temperatures. Specular CdTe and HgTe films have been grown at temperatures as low as 220 and 230 °C, respectively. Hall measurements performed on the HgTe films indicate good transport properties. The reduced stability of ditertiarybutyltelluride compared to other alkyl organotellurium compounds is consistent with relative stability results for branched hydrocarbon molecules.
New correlation technique for measuring short electrical pulses with picosecond time resolution
Authors: Paulus P. , Jäger D. , Pfeiffer Th. , Kuhl J.
Published: July 2002

In this letter we report a new purely electrical correlation measurement technique permitting time-resolved analysis of short electrical pulses. This technique provides a cheap and simple tool for measurements in the picosecond time domain, for instance, in the field of fast optoelectronics. In preliminary experiments, a time resolution of 26 ps has been obtained which exceeds the limits of conventional sampling oscilloscopes. The method offers the interesting advantage to be applicable to any short electrical pulse and does not require a synchronized optical pulse, in contrast to the optoelectronic correlation technique used so far in this time regime.
Generation of high peak power subpicosecond pulses in the 1.0–1.6 μm range by parametric amplification in an organic crystal
Authors: Ledoux I. , Zyss J. , Migus A. , Etchepare J. , Grillon G. , Antonetti A.
Published: July 2002

High peak power subpicosecond optical pulses have been generated by parametric amplification of a white-light femtosecond continuum in a new organic crystal, N-(4-nitrophenyl)-L-prolinol or (NPP), with an emission spectrum extending in the 1.0–1.6 μm range.
Photorefractive oscillation with intracavity image and multimode fiber
Authors: Fischer Baruch , Sternklar Shmuel , Weiss Shimon
Published: July 2002

A photorefractive oscillation between two cascaded passive phase conjugate mirrors (2C-PPCM) with intracavity phase and amplitude modulation and multimode fibers is described. The two semilinear PPCM’s operate via four wave mixing in BaTiO3 crystals. A single beam pumps only one PPCM and generates all other self-starting beams of the two PPCM’s
Comparison of crystal orientation dependence for the solid phase epitaxial process in ion implanted Si and GaAs
Authors: Licoppe C. , Nissim Y. I. , Henoc P.
Published: July 2002

Solid phase epitaxial (SPE) regrowth is studied using the time-resolved reflectivity technique in ion implanted semiconductors with different substrate orientations. In silicon evidence for a planar (100) growth front and a roughening (111) growth front is given. In GaAs the crystal/amorphous interface roughness is shown to increase with recrystallized depths in the (100) and (111) direction, the latter having the most degraded interfacial structure. The (110) substrate orientation in GaAs is shown to have a more stable interface during growth. The growth rate and activation energy of the SPE process is conserved in all GaAs orientations. While regrowth in silicon agrees qualitatively with the general crystal growth approach to growth on flat faces and kinked faces, the departure of GaAs from this scheme is explained by chemical disorder. Results support the hypothesis that the crystal/amorphous GaAs interface is rough and microfaceted in the (111) directions.
Electronically tunable distributed feedback lasers
Authors: Dutta N. K. , Piccirilli A. B. , Cella T. , Brown R. L.
Published: July 2002

The fabrication and performance characteristics of frequency tunable two-section distributed feedback lasers are reported. The lasers are of the double channel planar buried heterostructure type and utilize a second order grating for frequency selective feedback. The laser emits in a single frequency with a cw linewidth of ∼50 MHz. The single frequency output can be tuned by ∼2 Å by varying the current through one of the two sections. Electronically tunable sources of this type are potentially useful for coherent fiber transmission systems.
Dynamics of injected electron cooling in GaAs
Authors: Hayes J. R. , Levi A. F. J. , Weigmann W.
Published: July 2002

Using the technique of hot-electron spectroscopy we have measured the change in hot-electron spectra with transit region width enabling us to obtain a dynamic picture of injected hot-electron cooling in n+ GaAs. All features in the spectra have been identified and ‘‘ballistic’’ transport has been observed for samples having narrow transit region widths (<850 Å) while near diffusive transport has been observed for samples having wide transit region widths (>1700 Å). With increasing transit region width, rather than the electron distribution shifting en masse to lower energies, electrons are removed from the initial injected peak and scattered to lower energies close to the Fermi energy. This process of electron cooling is dramatically illustrated by measuring the magnetic field dependence of the hot-electron spectra.
Growth process in atomic layer epitaxy of Zn chalcogenide single crystalline films on (100)GaAs
Authors: Yao Takafumi , Takeda Toshihiko
Published: July 2002

Atomic layer epitaxy of zinc chalcogenide single crystalline films on a (001) GaAs substrate is studied. It is observed that the average thickness per one cycle of opening and closing the shutters of the constituent elements corresponds to one monolayer thickness. The initial and successive stages of the epitaxy are investigated by reflection high-energy electron diffraction. Three-dimensional growth mechanism dominates at the initial stage of the heteroepitaxy, while pseudo-two-dimensional growth mechanism dominates after the deposition of more than 1000 monolayers. However, the growth of ZnSe on ZnTe and vice versa is dominated by the two-dimensional growth mechanism.
Laser selective deposition of GaAs on Si
Authors: Bedair S. M. , Whisnant J. K. , Karam N. H. , Tischler M. A. , Katsuyama T.
Published: July 2002

GaAs films have been selectively deposited on Si substrates by laser induced chemical vapor deposition. An Ar+ laser was used to provide the required local heating on an otherwise relatively cool substrate to deposit GaAs spots and write GaAs lines. The deposition parameters were adjusted to deposit films with diameters in the range 1.5–500 μm and thicknesses in the range of 200 Å to several microns. Optical, chemical, and structural properties of the selectively deposited films have been studied. This technique can have potential applications in integrating optical and electronic devices on Si substrates.
Selective growth of InP buried structure by chloride vapor phase epitaxy
Authors: Hoshino Masataka , Tanaka Kazuhiro , Komeno Junji , Kitahara Kuninori , Kodama Kunihiko , Ozeki Masashi
Published: July 2002

Selective growth of an InP buried layer by In/PCl3/H2 vapor phase epitaxy was developed for buried layer GaInAsP/InP long wavelength laser diodes. For the first time, a completely flat-surface buried layer was grown into grooves with good morphology on a (100) exactly oriented InP substrate, but not on a (100) 2° off oriented substrate. We found that the side of the groove was covered with a buried InP layer in the early stage of epitaxial growth. Therefore, the present selective growth would be effective for the protection of the interface between the active and buried layers from thermal degradation. The resistivity of InP, measured by using an n-i-n structure, was found to be higher than 103 Ω cm at room temperature, which is sufficient for the buried layer of an usual laser diode.
Generation and detection of 15-ps light pulses in the 1.2–1.3-μm wavelength range by semiconductor lasers and detectors
Authors: Bimberg D. , Böttcher E. H. , Ketterer K. , Vollmer H. P. , Beneking H. , Roentgen P.
Published: July 2002

The generation of 15-ps light pulses at 1.23 and 1.26 μm having 200 mW peak power at a repetition rate of up to 10 MHz from directly modulated unbiased V-groove InxGa1−xAsyP1−y lasers is reported. Specially designed avalanche generators are employed for modulation of the laser injection current. The light pulses are analyzed using microstructured Ge photodetectors having a response of 62 ps at full width half-maximum. A deconvolution technique based on a theoretical analysis of the complete circuit of the detection system is applied to reduce the large error occurring normally when the characteristics of fast pulses are determined from the response of much slower detectors. This technique is proved by independent experiments to hold. A spontaneous lifetime of 1.5 ns of the charge carriers in the active layer of the laser is determined from the measured delay times between the optical and electrical pulses.
Parallel operation and crosstalk measurements in GaAs étalon optical logic devices
Authors: Jewell J. L. , Lee Y. H. , Duffy J. F. , Gossard A. C. , Wiegmann W.
Published: July 2002

We report the first parallel operation of GaAs optical logic elements and bistable devices. Arrays up to 2×4 in size were operated using a picosecond pump and probe technique, while in the bistable mode we achieved uniform response in two spots. Crosstalk due to carrier diffusion became noticeable at separations of typically ∼20–30 μm in the bistable devices. Pulsed operation at 82 MHz allowed separations down to ∼10 μm limited only by diffraction. Efficient heat sinking in the pulsed array resulted in negligible heating even when continually operated for many minutes. All experiments were performed at room temperature.
Effect of hydrogen on undoped and lightly Si-doped molecular beam epitaxial GaAs layers
Authors: Pao Yi-Ching , Liu D. , Lee W. S. , Harris J. S.
Published: July 2002

This letter describes a series of experiments in which pure hydrogen gas (at up to 1.2×10−6 Torr partial pressure) was introduced during molecular beam epitaxial (MBE) growth of low-doped and undoped GaAs at a substrate temperature of 580 °C. A major improvement in the electrical properties of the epitaxial layer has been observed. Electron mobilities at 77 K and deep level transient spectroscopy (DLTS) spectra are presented. A sharp increase in electron mobility and a dramatic reduction of M1 and M4 deep electron traps as shown by DLTS have been achieved with small amounts of H2 gas at 1.2×10−6 Torr partial pressure.
Fabrication of an integrated optical waveguide chemical vapor microsensor by photopolymerization of a bifunctional oligomer
Authors: Giuliani J. F. , Kim K. H. , Butler J. E.
Published: July 2002

A planar integrated optical waveguide chemical vapor microsensor has been fabricated on a glass substrate using a cw argon ion laser source to photopolymerize an initially bifunctional oligomer precursor. This fabrication technique allowed for the use of a relatively high refractive index photopolymerized transparent material to serve as both the light-guiding structure as well as the chemical sensing coating element simultaneously. Preliminary tests employing this structure in a continuously flowing nitrogen vapor system indicated that the sensing material can be used to detect the presence of ammonia and toluene vapors.
Hall-effect measurements in p-type InGaAs/GaAs strained-layer superlattices
Authors: Fritz I. J. , Dawson L. R. , Drummond T. J. , Schirber J. E. , Biefeld R. M.
Published: July 2002

We report, for the first time, temperature-dependent Hall data for holes in modulation-doped In0.2Ga0.8As/GaAs strained-layer superlattices. Samples with (compressive) planar strains of −0.5% to −1.2% in the InGaAs quantum wells were used, providing a range of configurations for the two (overlapping) sets of valence-band quantum wells derived from the bulk heavy- and light-hole bands. All samples exhibit transfer of holes into the InGaAs quantum wells at low temperature; however, the sample with the least strain shows evidence for gradual carrier freeze-out over a wide range of temperature.
Transistor action in novel GaAs/W/GaAs structures
Authors: Derkits G. E. , Harbison J. P. , Levkoff J. , Hwang D. M.
Published: July 2002

Structures containing thin polycrystalline layers of W embedded in essentially single crystal GaAs have been grown by molecular beam epitaxy. The W layers exhibit resistivities of 90–300 μΩ cm and Schottky barriers to both substrate and overgrown GaAs. The structures can act as metal gate transistors with β of 0.2–1.4 and α of 0.4–0.6. These are the first reported metal gate transistors in the III-V materials and the first using a nonepitaxial base and laterally seeded overgrowth. The use of a nonepitaxial base represents a degree of freedom which may be usefully exploited in a wide class of materials systems and may be important for the development of future metal gate transistors, especially in III-V materials.
Wave propagation in alternating solid and viscous fluid layers: Size effects in attenuation and dispersion of fast and slow waves
Authors: Schoenberg Michael , Sen Pabitra N.
Published: July 2002

In a system of alternating parallel elastic solid layers (plates) and viscous fluid layers (channels), two types of waves propagate parallel to the layers in the low-frequency limit. They are related to fast and slow waves in Biot’s theory of wave propagation in porous media. The slownesses s0 fast and s0 slow obtained previously for the case of inviscid fluid layers between elastic plates are modified to reflect dispersion and attenuation due to fluid viscosity. Two important dimensionless dynamic parameters are L=φH/δ, where H is the period width, φ is the relative width of the fluid channel, i.e., the ‘‘porosity,’’ and δ=(2ν/ω)1/2 is the viscous skin depth, and Ω=ωφH/α f which is channel width times the fluid wave number. Here ν is the kinematic viscosity of the fluid, α f is the fluid sound velocity, and ω is the radial frequency. In the frequency range for which L is very large L≫1 and Ω is very small Ω≪1, the attenuation and dispersion of both slow and fast waves exhibit similar dependences on L.

In particular, both wave velocities are decreased by an amount proportional to L−1(∼ω−1/2) and both have a quality factor Q proportional to L(∼ω1/2). To leading order in L−1 the wave slownesses have the form s2j=s20j[1+(1+i)Mj/L], j=fast or slow, where Mj are combinations of material and geometric parameters. The Q≡Re(s2)/Im(s2) factors are, for the fast wave, Qfast≊L/Mfast≊L/{[φρ f/(1−φ)ρ−ε]} and, for the slow wave, Qslow≊L/Mslow ≊L/(1+ε). ρ f and ρ are fluid and solid densities, respectively. ε is a usually small parameter given by 2(1−2γ)(ρ f/ρ)/ [α2pl/α2 f+(1−φ)ρ f/φρ−1], where γ is the square of the ratio of shear velocity to longitudinal velocity in the bulk solid and αpl is the velocity of long wavelength extensional plate waves.
High quality CdTe epilayers on GaAs grown by hot-wall epitaxy
Authors: Schikora D. , Sitter H. , Humenberger J. , Lischka K.
Published: July 2002

Hot-wall epitaxy is used for the first time for the growth of high quality CdTe epilayers on semi-insulating GaAs. The quality of the films is investigated by photoluminescence at 10 K, 78 K, and room temperature. The photoluminescence spectra at 78 K show a strong bound exciton recombination at about 1.58 eV with a linewidth of 11 meV. The linewidth of the bound exciton emission at 10 K is 1 meV. The electrical properties of the as-grown layers are measured by Hall effect yielding a hole concentration of p=3×1012 cm−3 and a mobility of 100 cm2/V s at 270 K.
Dependence of silicon-on-insulator transistor parameters on oxygen implantation temperature
Authors: Davis J. R. , Taylor M. R. , Spiller G. D. T. , Skevington P. J. , Hemment P. L. F.
Published: July 2002

Silicon-on-insulator films have been formed by high-dose oxygen implantation. Thermal donors, resulting from the residual oxygen content of the single crystal silicon region of the films, have been found to influence the electrical performance of transistors fabricated in them. The amount of oxygen in the active region of the silicon layer is strongly dependent on the oxygen implantation temperature. As the temperature is decreased below 500 °C an increasing thickness of oxygen-rich polycrystalline silicon is formed between the single crystal region and the buried oxide, causing the oxygen concentration in the single crystal region (and hence the thermal donor activity) to fall. As well as providing thermal donors, the residual oxygen also causes a lattice strain which increases the electron mobility.
Magnetic anisotropy in dc diode getter sputtered GdCo films—How important is the argon content in the films?
Authors: Bacon D. D. , Hong M. , Gyorgy E. M. , Gallagher P. K. , Nakahara S. , Feldman L. C.
Published: July 2002

Amorphous magnetic GdCo films were prepared by a dc diode getter sputtering technique with no bias field applied to the substrate during the film growth. Films (type I) obtained using 1.0 kV and 60 mTorr Ar during the sputtering show perpendicular anisotropy with Keffu =1.5×105 erg/cm3. Films (type II) deposited at 2.0 kV and 28 mTorr Ar exhibit magnetic isotropy with Kinu≊0. However, the actual argon content in the type II films is three times of that in the type I films. Nevertheless, the argon impurity in both the type I and type II films is ≤1.0 at. %, which is far less than those obtained in the biased rf diode sputtered GdCo films. Also, the distribution of argon is uniform in the film as observed from the Rutherford backscattering spectrometry.
Properties of AlGaAs buried heterostructure lasers and laser arrays grown by a two-step metalorganic chemical vapor deposition
Authors: Welch D. F. , Cross P. S. , Scifres D. R. , Streifer W. , Burnham R. D.
Published: July 2002

High quality buried heterostructure (BH) lasers were grown by a two-step metalorganic chemical vapor deposition. Single stripe BH lasers exhibited thresholds of 20 mA for a 1.2-μm stripe. The spectral output emits in a single transverse and longitudinal mode up to 15 mW, with a side lobe suppression greater than 23 dB at 5 mW output. BH laser arrays were fabricated with threshold currents of 130 mA and differential efficiencies of 70% for a 10-stripe array.
Ring-shaped domain effective for the Bloch line memory
Authors: Hidaka Yasuharu
Published: July 2002

A technique for stabilizing the ring-shaped stripe domain has been developed for improving the Bloch line memory. Selective grooving in the magnetic film provides for both formation and stabilization of the ring domain. The inside wall of the ring domain is used for ring domain stabilization, through its grooved edge affinity. The outside wall of the domain is stabilized away from the grooved edge by the natural domain width. The following features are found. (1) The ring-shaped domain is stable over a wide bias field range. (2) The demagnetizing field gradient, normal to the wall plane, can be kept almost the same at each position along the outside wall. (3) A stripe domain head can be formed controllably from a part of the ring-shaped domain, as required in the Bloch line memory for stripe-to-bubble domain conversion.
Far-field analytical model for laser arrays and fitting with experimental results
Authors: Berger J. , Fekete D.
Published: July 2002

Coupled laser arrays emit far-field radiation which is not well described by the grating-like formulation. An exact diffraction theory solution for the far field of coupled laser arrays is derived. The model is used to obtain excellent fit with the far-field pattern of a twin coupled laser diode operated under pulse modulation and with that of a hybrid coupled diode laser device. The fitted results exhibit the existence of a small phase difference between the coupled stripes and this difference is increased up to 12° in the hybrid device.
Polarization recovery in phase conjugation by modal dispersal
Authors: Kyuma Kazuo , Yariv Amnon , Kwong Sze-Keung
Published: July 2002

We demonstrate scalar phase conjugation, i.e., one in which both transverse components of the incident beam are phase conjugated, which is achieved by tandem combination of a mode scrambling fiber and a photorefractive passive phase conjugate mirror.
Atomistic Monte Carlo calculation of critical layer thickness for coherently strained siliconlike structures
Authors: Dodson Brian W. , Taylor Paul A.
Published: July 2002

Monte Carlo based techniques were used to study the stability of thin, coherently strained layers of mismatched siliconlike semiconductor material. The atomic interaction used for this study is the Stillinger–Weber potential [Phys. Rev. B 31, 5262 (1985)], modified to allow modeling of mismatched materials. Layers from 3 to 80 Å thickness were considered. For layers greater than about 20 Å thickness, the critical layer thickness is accurately described by the continuum theory of Matthews and Blakeslee [J. Cryst. Growth 27, 118 (1974)]. For thinner layers, however, the strain energy associated with misfit dislocations varies from the continuum value, resulting in smaller critical layer thickness, to the extent that critical mismatch as a function of layer thickness becomes nonmonotonic for the thinnest films considered.
Evidence of light-induced bond breaking in hydrogenated amorphous silicon
Authors: Hong C. S. , Hwang H. L.
Published: July 2002

Experimental evidence of bond breaking in hydrogenated amorphous Si films is presented, which accounts for the degradation of solar cell performance. For films with prolonged illumination, Fourier transform infrared spectroscopy showed distinct transitions occurring among various bonds, and electron paramagnetic resonance showed dangling bonds being produced. The bond breaking was reversible by thermal annealing.
Temperature dependence of shunt resistance in photovoltaic devices
Authors: Banerjee S. , Anderson W. A.
Published: July 2002

Shunt resistance in surface passivated Si solar cells has been experimentally shown to be temperature dependent with a maximum value of 2×107 Ω cm2. Mechanisms responsible for shunt resistance are identified as a combination of multistep tunneling and thermal trapping-detrapping of carriers through the defect states in the space-charge region.
Minority electron diffusion coefficient from lifetime measurement combination
Authors: Carotta Maria Cristina , Merli Marco , Passari Luigi , Susi Enrichetta
Published: July 2002

Minority electron diffusion coefficients as a function of dopant density are evaluated from the comparison between a steady state diffusion length (photoelectromagnetic effect) and a transient lifetime (photoconductivity decay) measurement. The reliability of the method is discussed with reference to the limits inherent to the two techniques. Within the limits of the experimental data dispersion, minority values comparable to the majority ones for the doping range 3×1014<ND<3×1017 are obtained.
High-speed enhancement mode InP metal-insulator-semiconductor field-effect transistors exhibiting very high transconductance
Authors: Antreasyan A. , Garbinski P. A. , Mattera V. D. , Temkin H.
Published: July 2002

We report the fabrication and performance of enhancement mode InP metal-insulator-semiconductor field-effect transistors having transconductances as high as 200 mS/mm for a gate length of 1 μm. The epitaxial layers of the structure have been grown by chloride vapor phase epitaxy. Electron beam evaporated SiO2 has been utilized as gate insulator. The metal-insulator-semiconductor field-effect transistors have low gate to source leakage currents (<125 nA) and saturation drift velocities as high as 3×107 cm/s. The transconductance value achieved in the present work is the highest ever measured on InP field-effect transistors.
Native oxide encapsulation for annealing boron-implanted Hg1−xCdxTe
Authors: Kao T.-M. , Sigmon T. W.
Published: July 2002

We report for the first time the successful use of the Hg1−xCdxTe native oxide as an encapsulation layer for an annealing process designed to activate an implanted impurity. The annealing process does not require Hg over pressure and consists of both furnace (∼200 °C) and rapid thermal (∼320 °C) anneals. Using 2.2 MeV 4He+ ion channeling measurements, we show that the implantation damage can be annealed out without loss of Hg from the substrate. Also, both secondary ion mass spectrometry and differential van der Pauw measurements indicate that the resulting electron concentration profile closely matches that of the implanted 11B profile and the electrical junction is found to lie close to the expected position of the metallurgical junction.
Stability of nitrogen-rich titanium nitride and zirconium nitride films
Authors: Salmenoja K. , Korhonen A. S. , Erola E. , Molarius J. M.
Published: July 2002

Thin titanium nitride (TiN) and zirconium nitride (ZrN) films containing excess nitrogen up to 62 and 65 at. % N, respectively, were deposited on austenitic stainless steel sheet substrates by triode ion plating at about 823 K. The nitrogen content of the films was determined using the nuclear resonance broadening technique based on the 15N(p,αγ)12C nuclear reaction and x-ray diffraction was used to study the phase compositions. Annealing experiments in evacuated quartz tubes were carried out at 773 and 1173 K to test the stability of the coatings. The results showed no essential differences for TiN before and after heat treatment. Slight indications of diffusion accompanied with the transformation of remaining α-Zr to ZrN were found in the case of ZrN films after heat treatment at the higher temperature of 1173 K.
Measurements of the critical resolved shear stress for indium-doped and undoped GaAs single crystals
Authors: Tabache M. G. , Bourret E. D. , Elliot A. G.
Published: July 2002

Direct measurements of the critical resolved shear stress of undoped and indium-doped GaAs single crystals at high temperatures have been performed using dynamical compression tests. At the melting point the critical resolved shear stress of GaAs:In is only twice that of undoped GaAs. At low temperatures, the activation energy for the motion of dislocations is not affected by indium doping. From these findings we conclude that crystallographic glide is not the only cause of dislocation formation in these GaAs crystals and solution hardening is not responsible for the reduction in dislocation density in GaAs:In.
Infrared optical properties of polycrystalline silver halide fibers
Authors: Sa’ar A. , Moser F. , Akselrod S. , Katzir A.
Published: July 2002

The power transmission characteristics at 10.6 μm, and the infrared spectral transmission from 2 to 13 μm, of extruded silver halide fibers of composition AgCl0.95Br0.05 have been investigated. The transmitted power at 10.6 μm remains linearly dependent on the input power up to at least 40 W, with a total loss coefficient of about 0.7 dB/m. The output power has a Gaussian shape with an angular width of 60° independent of the input power geometry in a fiber of about 2 m length. The spectral transmission shows a number of sharp absorption features attributed to water and CO−23 impurities, superimposed on a background loss that can be fit to an expression of the form (16.2λ−2+0.5) dB/m, with λ in μm. This background is a consequence of the scattering mechanism in these fibers.
Thickness-dependent void fraction of rf-sputtered amorphous Ge films by spectroscopic ellipsometry
Authors: McMarr P. J. , Blanco J. R. , Vedam K. , Messier R. , Pilione L.
Published: July 2002

In this letter it is shown that vapor deposited thin films prepared under conditions of low adatom mobility, such as amorphous Ge films in the present study, exhibit a nonlinear decrease in void fraction, and hence an increase in density with increasing film thickness. Fractal modeling of the internal void network structure in this class of vapor deposited films shows that the void boundaries define the surfaces of growth cones and these voids are, in general, not expected to be distributed uniformly with film thickness.
Surface oxidation of GaAs and AlGaAs in low-energy Ar/O2 reactive ion beam etching
Authors: Kinoshita Haruhisa , Ishida Toshimasa , Kaminishi Katsuzo
Published: July 2002

Ion beam etching (IBE) and reactive IBE (RIBE) of GaAs and AlxGa1−xAs(x=0.3–0.5) were examined using Ar and Ar/O2 (O2: 2.0 and 5.3 mol %). In Ar IBE of 100 eV or more, neither GaAs nor AlGaAs was substantially oxidized and equirate etching was observed. In 50 eV Ar/O2 (2–5.3%) RIBE, however, both GaAs and AlGaAs were oxidized and etched little. In 100 eV Ar/O2 (2%) RIBE, especially, AlGaAs was oxidized but GaAs was not, and a maximum selectivity of 13 was obtained in the etching of GaAs/Al0.5Ga0.5As. Impinging O+ ions were found to be the main origin of oxidation.
Planar monolithic integrated photoreceiver for 1.3–1.55 μm wavelength applications using GaInAs-GaAs heteroepitaxies
Authors: Razeghi M. , Ramdani J. , Verriele H. , Decoster D. , Constant M. , Vanbremeersch J.
Published: July 2002

We report the first fabrication of a monolithic integrated circuit consisting of a Ga0.47In0.53As planar photoconductive detector (suitable for 1.3–1.55 μm wavelength optical communication systems) associated with a GaAs field-effect transistor. The gain, response times, and noise properties of the photoconductive detector and the integrated photoreceiver have been investigated, taking into account particular aspects of the material and integrated circuit structure.
Extremely high quality Ga0.47In0.53As/InP quantum wells grown by chemical beam epitaxy
Authors: Tsang W. T. , Schubert E. F.
Published: July 2002

We have prepared by chemical beam epitaxy extremely high quality Ga0.47In0.53As/InP quantum wells with thickness as thin as 6 Å. Emission as short as 1.09 μm at 2 K (1.14 μm at 300 K) was obtained. Very sharp intense efficient luminescence peaks due to excitonic transitions were obtained from all quantum wells. The photoluminescence (PL) linewidths at 2 K were the narrowest that have been ever reported for Ga0.47In0.53As quantum wells grown by any technique. In fact, these Ga0.47In0.53As quantum well linewidths are at least equal to the narrowest linewidths ever reported for the perfected GaAs/AlAs and GaAs/AlxGa1−xAs quantum wells. These linewidths indicate the ‘‘effective’’ interface roughness to be 0.12 lattice constant, which can be interpreted as that the quantum well was largely consisting of a big domain of the same thickness Lz perforated with a small fraction of small domains of (Lz+a0/2), where a0 (=5.86 Å) is the lattice constant. No broadening due to band filling from impurities was found. Alloy broadening in Ga0.47In0.53As was limited to the intrinsic value of 1.3 meV. The PL energy upshifts measured in Ga0.47In0.53As quantum wells were in excellent agreement with theoretical values.
Nucleation and initial growth of GaAs on Si substrate
Authors: Rosner S. J. , Koch S. M. , Harris J. S.
Published: July 2002

The microstructure of thin layers of GaAs grown on Si substrates at low growth temperatures by molecular beam epitaxy was examined using transmission electron microscopy and MeV 4He+ ion channeling angular scan analysis. Crystalline island formation is observed at temperatures as low as 325 °C, with epitaxial orientation and distinct nucleation habits apparently tied to the symmetry of the misoriented substrate. For films with no exposure to temperatures above 405 °C, the planar strain is found to be compressive, up to a thickness of 100 nm.
Highly tunable and efficient room-temperature electroluminescence from GaAs doping superlattices
Authors: Hasnain G. , Döhler G. H. , Whinnery J. R. , Miller J. N. , Dienes A.
Published: July 2002

Using a novel technique of making highly selective contacts to GaAs doping superlattices, tunable electroluminescence (EL) is observed at room temperature with peak energies shifted up to 650 meV below the bulk band gap (λ>1.55 μm). The peak efficiency is about 2%. Comparison is made between the tunable EL spectra at different temperatures from 4 to 300 K and between samples with different doping concentration. Good agreement is obtained with theory.
Photopumped laser operation of AlxGa1−xAs-GaAs quantum well heterostructures with Se and Mg sheet doping
Authors: Kaliski R. W. , Holonyak N. , Hsieh K. C. , Nam D. W. , Burnham R. D. , Epler J. E. , Thornton R. L. , Paoli T. L.
Published: July 2002

Photoluminescence (77 and 300 K) and transmission electron microscopy (TEM) data are presented on AlxGa1−xAs-GaAs quantum well heterostructures with Se sheet doping in the GaAs quantum wells and Mg sheet doping in the AlxGa1−xAs (x∼0.2) barriers. Sheet or ‘‘spike’’ doping, which is surface deposited during the metalorganic chemical vapor deposition crystal growth, leads to a high impurity concentration and direct observation of the doping layer in TEM. Photopumped laser operation (77 and 300 K, pulsed and continuous) of compensated samples leads to modes 30–40 meV below the n=1 confined-particle electron-to-heavy-hole transition and involves the Se impurity. Mg spike doping of the barriers is used to compensate the Se doping of the wells, making the active region p type and thus allowing the observation of stimulated emission involving the ‘‘spike’’ distribution of Se.
Annealing kinetics during rapid and classical thermal processing of a laser induced defect in n-type silicon
Authors: Adekoya W. O. , Muller J. C. , Siffert P.
Published: July 2002

The annealing kinetics of the dominant defect [E(0.32 eV), σn=8×10−16 cm−2] induced in virgin Czochralski-grown n-type 〈100〉 1–5 Ω cm silicon by Nd-YAG laser (1.6 J cm−2, 0.53 μm) irradiation has been studied within the temperature range 500–650 °C using rapid and conventional thermal processing. With deep level transient spectroscopy measurements, we have observed an annealing rate increase about 30 times faster in the rapid thermal annealed (RTA) samples, than in those heat treated in a conventional furnace (CTA) with an activation energy difference ΔEA≂0.31 eV between the two processes, the latter requiring the higher energy. This difference results from ionization-enhanced annealing of this defect during RTA processing, a phenomenon which is markedly reduced in CTA-processed samples.