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27 Jan 1986

Volume 48, Issue 4, pp. 263-305


Theoretical study of a 16‐μm CO2 downstream‐mixing gasdynamic laser: A two‐dimensional approach

Purandar Chakravarthy and N. M. Reddy

Appl. Phys. Lett. 48, 263 (1986); http://dx.doi.org/10.1063/1.96575 (3 pages) | Cited 4 times

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A 16‐μm CO2‐N2 downstream‐mixing gasdynamic laser, where a cold CO2 stream is mixed with a vibrationally excited N2 stream at the exit of the nozzle, is studied theoretically. The flow field is analyzed using a two‐dimensional, unsteady, laminar and viscous flow model including appropriate finite‐rate vibrational kinetic equations. The analysis showed that local small‐signal gain up to 21.75 m−1 can be obtained for a N2 reservoir temperature of 2000 K and a velocity ratio of 1:1 between the CO2 and N2 mixing streams.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
47.15.-x Laminar flows
47.60.Kz Flows and jets through nozzles

High efficiency multikilojoule HF chemical lasers using an electron beam initiated low‐pressure mixture of H2/F2/NF3 or H2/F2/SF6

Fumihiko Kannari, Hirohito Inagaki, and Minoru Obara

Appl. Phys. Lett. 48, 266 (1986); http://dx.doi.org/10.1063/1.96576 (3 pages) | Cited 8 times

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High electrical and high chemical efficiencies were simultaneously achieved for the multikilojoule HF chemical laser using a Lambda‐type (inclined type) electron beam initiation scheme. The optimum addition of NF3 or SF6 fluorine donor could increase both efficiencies and could reduce the total pressure of the laser gas mixture. The laser output obtained from the low‐pressure mixture of H2/F2/O2/NF3=30/208/62.5/70 (Torr) was 4.5 kJ in a 50‐ns FWHM pulse width with an electrical laser efficiency of 226% and a chemical efficiency of 18.5%.
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42.55.Ks Chemical lasers
42.55.Lt Gas lasers including excimer and metal-vapor lasers
78.60.Ps Chemiluminescence

Field controlled light scattering from nematic microdroplets

J. W. Doane, N. A. Vaz, B.‐G. Wu, and S. Žumer

Appl. Phys. Lett. 48, 269 (1986); http://dx.doi.org/10.1063/1.96577 (3 pages) | Cited 530 times

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The light scattering and electro‐optic response of new material with display potential are investigated. The materials consist of microdroplets of nematic liquid crystals which are spontaneously formed in a solid polymer at the time of its polymerization. Droplet size, spacing, and distribution are readily controlled in these materials to allow optimization of displays based upon electrically controlled light scattering from the liquid crystal droplets. Preliminary experimental and theoretical studies of the light scattering properties show these materials to offer new features suitable for many display applications.
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78.20.Jq Electro-optical effects
85.60.Pg Display systems
07.07.Hj Display and recording equipment, oscilloscopes, TV cameras, etc.
75.20.Ck Nonmetals

Nonlinear optical coupling to planar GaAs/AlGaAs waveguides

Y. J. Chen, G. M. Carter, G. J. Sonek, and J. M. Ballantyne

Appl. Phys. Lett. 48, 272 (1986); http://dx.doi.org/10.1063/1.96578 (3 pages) | Cited 11 times

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Nonlinear optical coupling to planar GaAs/AlGaAs waveguides has been observed at 1.06 μm using a grating coupling technique. At an input intensity of 100 MW/cm2, intensity dependent nonlinear switching to the waveguide mode occurs. The results indicate a fast nonlinear response time.
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42.79.Gn Optical waveguides and couplers
42.65.-k Nonlinear optics
42.79.Dj Gratings
42.82.-m Integrated optics

Magnetically tunable diluted magnetic semiconductor (Cd, Mn)Te quantum well laser

E. D. Isaacs, D. Heiman, J. J. Zayhowski, R. N. Bicknell, and J. F. Schetzina

Appl. Phys. Lett. 48, 275 (1986); http://dx.doi.org/10.1063/1.96579 (3 pages) | Cited 22 times

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We report the first observation of strong magnetic field tuning of laser emission from Cd1−xMnxTe/Cd1−yMnyTe multiple quantum well structures. The spectral peak of the stimulated emission shifts to lower energy with increasing field at a rate of 3.4 meV/T to a maximum shift of 34 meV at 10 T. This is about five times slower than in bulk Cd1−xMnxTe with a comparable x value. Stimulated emission was observed for samples cooled to 1.9 K when optically pumped with a Nd:YAG laser.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Px Semiconductor lasers; laser diodes
78.45.+h Stimulated emission

Direct measurements of liquid/solid interface kinetics during pulsed‐laser‐induced melting of aluminum

J. Y. Tsao, S. T. Picraux, P. S. Peercy, and Michael O. Thompson

Appl. Phys. Lett. 48, 278 (1986); http://dx.doi.org/10.1063/1.97015 (3 pages) | Cited 25 times

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We report time‐resolved electrical‐resistance measurements obtained during pulsed‐laser melting of a metal. Through heat‐flow calculations and solute‐diffusion measurements, the measured resistances are correlated with the thresholds for partial and full melting of a thin film of aluminum. Furthermore, simultaneous time‐resolved reflectance measurements establish that, in this geometry, melting and solidification proceed via the motion of a well‐defined, planar liquid/solid interface, whose position can be deduced from the resistance measurements. These measurements permit, for the first time, real‐time determinations of melt‐depth histories in fundamental studies of rapid solidification processing of metals.
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64.70.D- Solid-liquid transitions
68.08.-p Liquid-solid interfaces
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
81.30.Mh Solid-phase precipitation
73.61.At Metal and metallic alloys

Effects of buffer layers in GaAs‐In0.2Al0.8As strained‐layer superlattices

M. Nakayama, K. Kubota, H. Kato, S. Chika, and N. Sano

Appl. Phys. Lett. 48, 281 (1986); http://dx.doi.org/10.1063/1.96580 (3 pages) | Cited 5 times

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Raman spectroscopy has been used to study strains in GaAs‐In0.2Al0.8As strained‐layer superlattices with a fixed layer thickness (100–100 Å) and various InxAl1−xAs buffer layers [x=0 (GaAs in place of AlAs), 0.1, and 0.2]. Strain‐induced frequency shifts of the longitudinal optic phonon modes depend on the alloy composition (lattice constant) of the buffer layer. For the GaAs buffer layer (x=0) the mismatch between the superlattice and the buffer layer is accommodated by dislocations near the interface region, while for the In0.2Al0.8As buffer layer the mismatch is accommodated by the tensile strain in the GaAs layers.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.30.Hv Other nonmetallic inorganics
68.35.Gy Mechanical properties; surface strains
68.35.Dv Composition, segregation; defects and impurities

Spectral characterization of epitaxial crystal layers, using a fiber stimulated Raman light generator as light source

Yoh Mita

Appl. Phys. Lett. 48, 284 (1986); http://dx.doi.org/10.1063/1.96581 (3 pages)

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Spectral absorption characteristics in InGaAsP/InP double heterostructure epitaxial crystal layers have been investigated by using stimulated Raman scattering light from silica fiber excited with neodymium:yttrium aluminum garnet laser and by examining the transmitted guided light. The method proved useful in measuring wavelength‐dependent optical absorption ranging between 0.1 and 20 cm−1 in epitaxial layers with waveguiding structures as well as characterizing loss in optical waveguides in the wavelength region between 1.06 and 1.7 μm.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.79.Gn Optical waveguides and couplers
75.20.Ck Nonmetals
78.30.Hv Other nonmetallic inorganics

Deep level defect study of molecular beam epitaxially grown silicon films

Y. H. Xie, Y. Y. Wu, and K. L. Wang

Appl. Phys. Lett. 48, 287 (1986); http://dx.doi.org/10.1063/1.96582 (3 pages) | Cited 3 times

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We report the result of the study on the electrically active deep level defects in Si films grown by molecular beam epitaxy. A deep level defect at Ec−0.58 eV is consistently obtained for samples grown on substrates with purposely contaminated surfaces. The observed defects are all located within 3000–5000 Å of the epilayer‐substrate interface with concentrations in or below 1014 cm−3 range. Secondary ion mass spectroscopic study results indicate the correlation between the substrate surface residual carbon concentration and the observed defect concentration. These defects appear to be higher order defects rather than the single level defects, as evidenced by the asymmetry of the deep level transient spectra. For samples grown on the substrates cleaned using an established surface cleaning method, no deep level defects within the detection limit (∼1012 cm−3 in our case) are observed.
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73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
78.40.Fy Semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Determination of the microscopic quality of InGaAs‐InAlAs interfaces by photoluminescence—Role of interrupted molecular beam epitaxial growth

F‐Y. Juang, P. K. Bhattacharya, and J. Singh

Appl. Phys. Lett. 48, 290 (1986); http://dx.doi.org/10.1063/1.96583 (3 pages) | Cited 16 times

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Photoluminescence (PL) studies have been carried out on 120 Å InGaAs/InAlAs single quantum well structures grown by molecular beam epitaxy. Three types of samples were grown with the growth being interrupted before interface formation. The interruption times were 0, 2, and 3 min. The corresponding linewidth of the main excitonic transition associated with the quantum well was found to be 20, 16, and 10 meV, respectively, while the PL intensity changed by the ratio 1:0.4:0.1. We believe this behavior is due to a steady improvement in the interface quality due to interruption accompanied by impurity accumulation during the interruption. Analysis of the 10 meV linewidth, which is among the smallest ever reported, suggests that the InAlAs/InGaAs interface can be described by two‐dimensional InAlAs and InGaAs islands which have a height of two monolayers and a lateral extent of about 100 Å.
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68.35.Fx Diffusion; interface formation
78.40.Fy Semiconductors
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Observation of giant induced voltages in high mobility GaAs‐AlxGa1−xAs heterostructures in the quantized Hall regime

D. A. Syphers, K. P. Martin, and R. J. Higgins

Appl. Phys. Lett. 48, 293 (1986); http://dx.doi.org/10.1063/1.96584 (3 pages) | Cited 4 times

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We report studies on the use of the very low resistivity ( ρxx∼0) of GaAs‐AlxGa1−xAs heterostructures in the quantized Hall regime (QHR). It is shown that low‐frequency inductive coupling to this system can result in radial charge transport, and is perhaps the first use of the QHR lossless properties free of losses from the Hall resistance ρxy. We show that this effect provides an easy way to measure the value of ρxx throughout a quantized Hall plateau, and the effect of capacitance between contacts is discussed.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.De Semiconductor-device characterization, design, and modeling

Growth of a ZnSe‐ZnTe strained‐layer superlattice on an InP substrate by molecular beam epitaxy

Masakazu Kobayashi, Naoki Mino, Hironori Katagiri, Ryuhei Kimura, Makoto Konagai, and Kiyoshi Takahashi

Appl. Phys. Lett. 48, 296 (1986); http://dx.doi.org/10.1063/1.96585 (2 pages) | Cited 26 times

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A ZnSe‐ZnTe strained‐layer superlattice (SLS) was grown on an InP substrate by molecular beam epitaxy for the first time. The x‐ray diffraction measurement technique was used to confirm the existence of the high quality SLS structure. Overall quality may also be inferred from the observed quantum size effects of the photoluminescence data.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology

GaSe detectors for x‐ray beams

Alfredo Castellano

Appl. Phys. Lett. 48, 298 (1986); http://dx.doi.org/10.1063/1.96586 (2 pages) | Cited 16 times

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The possibility of using GaSe detectors for x‐ray beams dosimetry has been evaluated. Direct current produced by high fluxes of 130 and 170 kV x ray at different exposure rates was measured.
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87.53.Bn Dosimetry/exposure assessment
07.85.-m X- and γ-ray instruments

Low‐temperature nuclear magnetic resonance with a dc SQUID amplifier

M. R. Freeman, R. S. Germain, R. C. Richardson, M. L. Roukes, W. J. Gallagher, and M. B. Ketchen

Appl. Phys. Lett. 48, 300 (1986); http://dx.doi.org/10.1063/1.96587 (3 pages) | Cited 8 times

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We report the detection of nuclear magnetic resonance at 4 K and 1.9 MHz with a receiver based on a thin‐film dc superconducting quantum interference device. The noise temperature of the spectrometer is 300 mK, limited by the second stage amplifier.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
85.25.-j Superconducting devices

Ion beam mixing in the Al/NixAl1−x/Ni system

E. Rimini, M. Nastasi, J. Liu, J. C. Barbour, J‐P. Hirvonen, and J. W. Mayer

Appl. Phys. Lett. 48, 303 (1986); http://dx.doi.org/10.1063/1.96588 (3 pages) | Cited 3 times

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Thin‐film alloy samples of Al/NixAl1−x/Ni (x=0.75, 0.5, 0.25) were irradiated at room temperature and at 160 °C with 280 and 560 keV Xe ions to a dose of 1.1×1016 Xe ions/cm2. The samples were analyzed by Rutherford backscattering spectrometry. In the Al/Ni3Al/Ni configuration the Ni3Al layer mixes more strongly with Al than with Ni. In the Al/NiAl/Ni samples, the NiAl layer mixes substantially with both Al and Ni. In the Al/NiAl3/Ni case, the NiAl3 layer mixes only with Ni. The results differ from thermal annealing behavior and are explained in terms of the thermodynamical driving forces present in the different samples.
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61.80.Jh Ion radiation effects
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
64.75.-g Phase equilibria
68.55.Nq Composition and phase identification
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