By Topic

Applied Physics Letters

Issue 11 • Date Dec 1980

Filter Results

Displaying Results 1 - 25 of 33
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (112 KB)  
    Freely Available from IEEE
  • Effect of flow velocity on the photon statistics of a cw dye laser

    Page(s): 973 - 975
    Save to Project icon | PDF file iconPDF (232 KB)  

    The effect of changing the velocity of dye flow on the behavior of a cw dye laser is investigated by photon counting measurements. The results strongly suggest that changing the velocity over the range 10–13 m/sec merely changes the pump parameter, but leaves the other laser characteristics essentially unaltered. The average light intensity is found to be a linear function of flow velocity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High‐speed laser modulation with integrated optical injection

    Page(s): 975 - 978
    Save to Project icon | PDF file iconPDF (338 KB)  

    We report operation of an integrated diode laser device, which utilizes light injected from a pump curved waveguide branch terminated by a reflecting facet to provide feedback. This waveguide geometry eliminates relaxation oscillations while simultaneously decreasing the response time of the laser to pulsed current modulation. Randomly timed pulses as short as 250 psec duration are observed and this value results from limitations of the electronics and not the laser. An analysis indicates the roles of the various parameters. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optoacoustic determination of photocarrier generation efficiencies of dye films

    Page(s): 978 - 981
    Save to Project icon | PDF file iconPDF (374 KB)  

    An optoacoustic method is used for the first time to study photoconductive efficiencies of thin dye films coated on a substrate. A piezoelectric transducer is attached to the substrate, and the dye film is excited by a modulated cw laser beam, of intensity less than 0.1 mW/cm2. Strong signal enhancement occurs when the laser modulation frequency is equal to a fundamental mechanical resonance frequency of the sample‐transducer assembly (about 40 kHz in our experiment). The quantum efficiency for photocarrier generation is derived by measuring the decrease in optoacoustic signal when an electric field is applied to the sample. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cavity‐length stabilization technique for synchronously pumped mode‐locked lasers

    Page(s): 981 - 984
    Save to Project icon | PDF file iconPDF (380 KB)  

    We demonstrate a technique for active stabilization of the cavity length of synchronously pumped mode‐locked lasers. The technique is general and relies on the ultrashort‐pulse forming process itself. It can be implemented in a variety of nonparasitic ways, has high sensitivity to changes in true optical path length of the cavity, and offers the possiblity of long‐term stabilization. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface acoustic wave planar prism waveguide coupler

    Page(s): 985 - 987
    Save to Project icon | PDF file iconPDF (249 KB)  

    The design and experimental measurements of a planar prism waveguide coupler on YZ lithium niobate are presented. The coupler was used to compress a 60‐wavelength‐aperture surface acoustic wave into a 3‐wavelength‐wide Δv/v waveguide. The coupling efficiency was measured to be within 1 dB of the theoretical maximum 80% at the center frequency of 300 MHz. A 1.5‐dB coupling bandwidth of 45 MHz was observed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Single‐growth embedded epitaxy AlGaAs injection lasers with extremely low threshold currents

    Page(s): 987 - 989
    Save to Project icon | PDF file iconPDF (286 KB)  

    A new type of strip‐geometry AlGaAs double‐heterostructure laser with an embedded optical waveguide has been developed. The new structure is fabricated using a single step of epitaxial growth. Lasers with threshold currents as low as 9.5 mA (150 μm long) were obtained. These lasers exhibit operation in a single spatial and longitudinal mode, have differential quantum efficiencies exceeding 45%, and a characteristic temperature of 175° C. They emit more than 12 mW/facet of optical power without any kinks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Feedback‐induced line broadening in cw channel‐substrate planar laser diodes

    Page(s): 990 - 992
    Save to Project icon | PDF file iconPDF (254 KB)  

    The effect of optical feedback on the spectral characteristics of channel‐substrate planar single‐mode laser diodes operating at room temperature is reported. The impact on the performance of interferometric sensor systems using such sources is discussed. The linewidth for the free‐running laser at 10‐mW output power was determined to be less than 5 MHz at room temperature. Broadening on the order of 40 times the intrinsic linewidth was observed for 0.1% feedback and increased with increasing feedback. The presence of self‐oscillation modes was observed at 0.04% feedback. Satellite modes symmetrically located with respect to the primary mode appeared in the spectrum for feedback greater than 0.04%. These satellite modes are attributed to self‐oscillation in the laser induced by feedback. As the feedback was increased, the satellite mode spectrum began to overlap that of the primary mode, reducing the effective coherence length from 60 m (for the single‐mode linewidth) to less than a few centimeters. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fundamental‐mode VHF/UHF minature acoustic resonators and filters on silicon

    Page(s): 993 - 995
    Save to Project icon | PDF file iconPDF (191 KB)  

    Novel bulk acoustic‐wave high‐Q resonators and acoustically coupled resonator filters have been fabricated and operated at their fundamental half‐wavelength mode in the 200‐500‐MHz frequency range. These structures are fabricated on thin ZnO/silicon diaphragms with dimensions small enough to be incorporated within integrated circuits. Resonator Q’s near 2600 at the fundamental mode have been obtained and strong inter‐resonator acoustic coupling has been achieved yielding filters having insertion loss (untuned) as low as 5.5 dB. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface acoustic wave characteristics of a single crystal of potassium lithium niobate

    Page(s): 996 - 997
    Save to Project icon | PDF file iconPDF (177 KB)  

    The surface acoustic wave (SAW) characteristics of a single crystal of potassium lithium niobate K2.98Li1.55Nb5.11O15 are calculated using published data. It is found that there are two sets of propagation planes and directions having zero temperature coefficient of SAW delay time. One set has a large electromechanical coupling factor (K2s=0.9%) and a zero power flow angle. The temperature stability of this crystal is located between that of T13TaSe4 and ST‐cut quartz. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multifrequency x‐ray backlighting of laser‐imploded targets

    Page(s): 998 - 1000
    Save to Project icon | PDF file iconPDF (239 KB)  

    The compression of a 3.5‐atm‐neon‐filled glass microballoon was recorded by time‐resolved multifrequency x‐ray backlighting with a gallium x‐ray source which covers a suitable frequency region. A product of compressed density and radius ρR of (1.5–3.5)×10-4 g cm-2 and core temperature of greater than 200 eV were estimated from the spectral absorption characteristics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A lateral microscopic growth model for heterogeneous impurity incorporation during Czochralski crystal growth

    Page(s): 1001 - 1003
    Save to Project icon | PDF file iconPDF (353 KB)  

    The occurrence of heterogeneous impurity incorporation during growth of Czochralski silicon and germanium crystals is attributed to a microscopic kinetic mechanism of terrace growth. This is deduced from the close correspondence of striation patterns in bulk crystals with terrace traces in GaAs layers grown by liquid phase epitaxy. A simplified but generally applicable model of terrace growth for both epitaxial layers and bulk crystals is presented. The model does not depend on the occurence of constitutional supercooling. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Real‐time x‐ray topography studies of the viscoelastic behavior of SiO2 in the system Si/SiO2

    Page(s): 1004 - 1005
    Save to Project icon | PDF file iconPDF (153 KB)  

    The viscoelastic behavior of SiO2 in the system Si/SiO2 during isothermal heat treatment is studied by directly imaging the x‐ray topography contrast due to lattice strains at oxide edges of test structures. We measure the relaxation time of those strains, e.g., the time to reach zero x‐ray contrast, at different temperatures above 900 °C, the minimum temperature for plastic deformation of SiO2. An Arrhenius plot of the relaxation time yields activation energies for viscous flow of 4.3 for normal‐ and 2.3 eV for high‐pressure thermal SiO2. For small rectangular oxide windows we find the relaxation time proportional to the square root of the window area. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Au and Al interface reactions with SiO2

    Page(s): 1006 - 1008
    Save to Project icon | PDF file iconPDF (327 KB)  

    The chemical bonding, extent, and evolution of metal‐oxide semiconductor interface regions have been probed with soft‐x‐ray photoemission spectroscopy following room‐temperature, in situ metallization. We identify strong atomic rearrangement and charge transfer at metal‐SiO2 interfaces. The quantitatively different processes found for Au and Al suggest new structural models. For Al‐SiO2, Al first clusters about each surface O and then grows Al2O3 by reducing SiOx (X ≪ 2) and leaving excess Si at the interface. In contrast, Au forms islands on SiO2 with evidence of Au–Si bonding, causing an SiOx layer beneath the contact. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of solar cell performance to calculations using different energy band‐gap narrowing models

    Page(s): 1009 - 1011
    Save to Project icon | PDF file iconPDF (190 KB)  

    Three different energy band‐gap narrowing models were used for exact numerical calculations of silicon solar cell performance. The results are compared to data from high‐efficiency cells. Two of the gap narrowing models are derived empirically from other types of devices, and the third is theoretical. The applicability of the models to these cells is demonstrated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of laser light on the sticking coefficient in ZnS thin‐film growth

    Page(s): 1012 - 1013
    Save to Project icon | PDF file iconPDF (202 KB)  

    Some preliminary results are presented concerning an effect of laser light (λ=4880 Å) on the growth of an evaporated ZnS film. We observe an increase in thickness in the region of the film illuminated by laser light. The spatial resolution is high and the observed phenomenon is not thermal in origin. A simple and unique method for investigating the dynamics of the effect during its evolution is described. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A high‐speed Si lateral photodetector fabricated over an etched interdigital mesa

    Page(s): 1014 - 1016
    Save to Project icon | PDF file iconPDF (324 KB)  

    A new kind of high‐speed photodetector has been constructed utilizing the anisotropic etching technique. It is demonstrated that, functioning as an edge‐incident photodiode, the detector responds reliably to subnanosecond light pulses with 40% overall quantum efficiency. And, functioning as a phototransistor, it responds to cw radiation with a current gain. Compatibility with existing planar processing is another feature. Possible mechanisms involved are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparative structural and electrical characterization of scanning‐electron‐ and pulsed‐laser‐annealed silicon

    Page(s): 1016 - 1018
    Save to Project icon | PDF file iconPDF (430 KB)  

    Silicon implanted with As+, P+, or B+ ions has been annealed by the multiple‐scan electron beam method and by use of pulsed radiation from a Q‐switched ruby laser. Electron microscope examination of specimen cross section gives direct comparison of the initial implantation damage with the structures produced by the different annealing methods. Sample electric conductivities after annealing are also compared. This work highlights the differences between the liquid‐ and solid‐phase annealing mechanisms of the pulsed‐laser and scanned‐electron‐beam methods, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Direct observation of laser‐induced solid‐phase epitaxial crystallization by time‐resolved optical reflectivity

    Page(s): 1019 - 1021
    Save to Project icon | PDF file iconPDF (249 KB)  

    Direct measurement of solid phase epitaxial crystallization during cw laser annealing of ion‐implanted silicon is reported. The measurement technique utilizes optical interference effects between reflected light from the sample surface and from the epitaxial growth plane to time‐resolve the growth process with high spatial resolution. Laser‐induced solid phase epitaxial growth was monitored for two values of incident laser power; corresponding epitaxial growth rates and calculated surface temperatures are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reactive‐ion etching of GaAs and InP using CCl2F2/Ar/O2

    Page(s): 1022 - 1024
    Save to Project icon | PDF file iconPDF (337 KB)  

    We describe the reactive ion etching of GaAs, InP, and their derivative compounds using an etch gas composed of CCl2F2, O2, and argon. Etching was generally carried out at pressures between 1 and 10 μ, and power densities below 0.8 W/cm2. Clean etch profiles were obtained with etch rates as high as 0.25 μm/min. A strong dependence of etch rate on pressure was observed with a maximum at 5 μ total pressure. The etch profiles exhibited a ’’negative undercut’’ character which was also dependent upon the total pressure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Heteroepitaxy of Ge1-xSix on Si by transient heating of Ge‐coated Si substrates

    Page(s): 1024 - 1027
    Save to Project icon | PDF file iconPDF (318 KB)  

    Heteroepitaxial films of Ge1-xSix alloys have been obtained by transient heating of Ge‐coated Si single‐crystal substrates with a graphite strip heater. Structural characterization shows the films to be of good epitaxial quality. As the maximum temperature during heating is increased, the Ge content and the microtwin density of the films decrease. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nucleation‐controlled overgrowth of silicon on silica

    Page(s): 1028 - 1030
    Save to Project icon | PDF file iconPDF (433 KB)  

    We have demonstrated the nucleation‐controlled overgrowth of silicon single crystals on an oxidized silicon wafer. The crystals are grown from an Al‐Si liquid film by nucleation at via holes in the oxide substrate. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Calculation of the Auger line at the Si/SiO2 interface

    Page(s): 1031 - 1032
    Save to Project icon | PDF file iconPDF (173 KB)  

    The Auger line shape has been calculated for the surface of (100) silicon, using a semiempirical tight‐binding slab model. Chemisorbed oxygen was considered by having the oxygen atom (or molecule) satisfy the double dangling bond of the surface atoms. The presence of the chemisorbed oxygen caused a shift of the outer‐layer local density of states in such a manner to create additional structure in the N(E) distribution for the Auger transition. This structure correlates well with such structure reported recently by several experimental groups. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High mobilities in AlxGa1-xAs‐GaAs heterojuntions

    Page(s): 1033 - 1035
    Save to Project icon | PDF file iconPDF (266 KB)  

    Electron mobilities as high as 6485 cm2/V sec at 300 and 57 260 cm2/V sec at 78 K were obtained in Al0.33Ga0.67As‐GaAs modulation‐doped single‐period heterojunctions with an average electron concentration of ∼1017 cm-3. The achievement of such high mobility is the result of leaving part of the AlGaAs near the interface undoped. By varying the thickness of this undoped region, electron mobilities much greater than for uniformly doped AlGaAs in modulation‐doped structures have been achieved. The electron mobility enhancement has been observed to increase with the increase of the undoped region, reach a maximum, and then decrease. Mobility enhancement was still observed up to the point of leaving a 200‐Å undoped region in the AlGaAs. The peak mobilities for an AlAs mole fraction of 33% has been found to occur for an undoped region of 50 Å while for 25% the mobility peaks for 100 Å. The Al0.25Ga0.75As‐GaAs modulation‐doped structure had a slightly lower peak mobility, namely 50 234 cm2/V sec at 78 K. These results indicate a mobility improvement of about a factor of 2 over previously reported modulation‐doped AlGaAs‐GaAs structures at 78 K. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scanned electron beam annealing of arsenic‐implanted silicon

    Page(s): 1036 - 1037
    Save to Project icon | PDF file iconPDF (201 KB)  

    A scanning electron beam system for the annealing of ion‐implanted solids is described. Annealing of 〈100〉 silicon implanted with arsenic (120 keV, 3×1015 As/cm2) was investigated. Analysis by 1.2‐MeV 4He channeling allowed the detailed monitoring of the recrystallization process, which occurs by means of a solid‐phase mechanism. The role of the various parameters such as electron beam power and application time has been explored. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics.

Full Aims & Scope

Meet Our Editors

Editor
Nghi Q. Lam
Argonne National Laboratory