By Topic

Applied Physics Letters

Issue 2 • Date Jan 1980

Filter Results

Displaying Results 1 - 25 of 28
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (98 KB)  
    Freely Available from IEEE
  • Tunable vacuum ultraviolet laser action by argon excimers

    Page(s): 113 - 115
    Save to Project icon | PDF file iconPDF (230 KB)  

    Vacuum ultraviolet lasing was achieved in electron‐beam‐pumped high‐density argon gas (25–65 bars). With a diffraction grating, the argon excimer laser (126 nm) could be tuned between 123.2 and 127.4 nm. The line width of the tuned laser was 0.6 nm and the output power ∼1 kW. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nuclear‐pumped cw lasing of the 3He‐Ne system

    Page(s): 115 - 117
    Save to Project icon | PDF file iconPDF (264 KB)  

    The gain for the 6328‐Å laser line for the nuclear excited He‐Ne system has been measured for 300 Torr pressure at thermal neutron flux levels from 2×107 to 1×1014 n/cm2 sec. In order to estimate small:signal gain, the gain was also measured as a function of input intensity. For demonstration of feasibility of cw operation of nuclear pumped lasers, a cavity was operated and lasing was observed. Although the laser output was small, we conclude that lasing in a cw mode has been achieved with He‐Ne using moderate neutron flux levels. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effect of substrate temperature on the current threshold of GaAs‐AlxGa1-xAs double‐heterostructure lasers grown by molecular beam epitaxy

    Page(s): 118 - 120
    Save to Project icon | PDF file iconPDF (271 KB)  

    The current threshold densities (Jth) of broad‐area double‐heterostructure (DH) lasers, the photoluminescence (PL) intensities of the p‐GaAs cap layers, P‐AlxGa1-xAs (x∼0.3) confinement layers, and the GaAs active layers of the DH wafers are investigated as a function of the substrate temperature (450–650 °C) during MBE growth. The PL intensities of the P‐AlxGa1-xAs (x∼0.3) confinement layers and the GaAs active layers increase and the Jth’s of the DH lasers decrease with increasing substrate temperature. The improvement of Jth with increasing substrate temperature is found to be well correlated to the improvement of the optical qualities of the AlxGa1-xAs layers with increasing substrate temperature. However, the PL intensities of the p‐GaAs cap layers are relatively independent of substrate temperature. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transverse mode stabilized AlGaAs/GaAs plano‐convex waveguide laser made by a single‐step liquid phase epitaxy

    Page(s): 121 - 123
    Save to Project icon | PDF file iconPDF (274 KB)  

    A new laser structure, the plano‐convex waveguide (PCW) laser is described. A thickness‐varied waveguide layer used for transverse mode stabilization was formed adjacent to the planar active layer. The laser structure was fabricated by a single‐step liquid phase epitaxial growth on a grooved substrate. With pulsed injection, stable fundamental transverse mode operation was observed up to 3.5 times threshold current, where power output was 36 mW/facet. At zero dc bias, single longitudinal mode was attained after 10 ns of the leading edge of the optical pulse. Far‐field beam divergences of about 10° and 50° were obtained in directions parallel and perpendicular to the junction plane, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three‐dimensional heat flow in the photoacoustic effect

    Page(s): 123 - 125
    Save to Project icon | PDF file iconPDF (264 KB)  

    The theory of the photoacoustic effect is generalized to include three‐dimensional heat flow. For typical experimental conditions the predicted photoacoustic signal is precisely the same as that from previous one‐dimensional models, subject only to the restriction that thermal waves transverse to the incident beam do not reach the cell walls. This conclusion applies to both thermally thick and thermally thin sample or gas. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pulsed CO2 laser interaction with a metal surface at oblique incidence

    Page(s): 125 - 127
    Save to Project icon | PDF file iconPDF (302 KB)  

    Thermal fluence deposition and surface pressure generation produced by a CO2 laser pulse (λ=10.6 μm, during 10 μs, maximum intensity 3 MW/cm2) have been measured as a function of angle of incidence ϑ on sheet aluminum in air. We find that air plasma ignition depends on the laser beam intensity I0 only, not on the surface‐normal flux I0 cosϑ. Conversely, the fluence deposition and surface pressure depend only on the product I0 cosϑ, and obey the square‐root and two‐thirds‐power dependences observed with simple I0 variation at normal incidence. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electron density measurement by deflection of a far‐infrared beam

    Page(s): 128 - 130
    Save to Project icon | PDF file iconPDF (255 KB)  

    Electron densities in the range 3×1014≪Ne≪6×1015 cm-3 have been determined in a laser‐initiated linear discharge using a novel far‐infrared method. The density was determined by measuring deflections of a 119‐ and 171‐μm far‐infrared beam from an optically pumped CH3OH laser. The far‐infrared beam was guided both inside and outside of the plasma chamber using dielectric waveguides. The spatial distribution of electron density for peak discharge currents of 2–4 kA and at distances of 8–25 mm from the laser focus on the target was found to be given by Ne (r,ϑ,I) =3×1014I1.9r-2.4 cosω cm-3, where I is the discharge current in kA, r is the radius from the laser focus on the target in cm, and ϑ is the polar angle from the target axis. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermo‐optical spectroscopy: Detection by the ’’mirage effect’’

    Page(s): 130 - 132
    Save to Project icon | PDF file iconPDF (262 KB)  

    A new thermo‐optical method based on the sensitive detection of thermal gradients adjacent to heated sample surfaces is described. Room‐ and low‐temperature experiments were performed using this technique, and its advantages over different methods are discussed. View full abstract»

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

    Page(s): 132 - 134
    Save to Project icon | PDF file iconPDF (222 KB)  

    Transition moments and energies have been calculated for the X‐A, bound to continuum, transition in HgCl. The photodissociation cross section at the peak (∼20 000 cm-1 or 500 nm) is 1.2×10-18 cm2 at 600 K. The laser energy 17 921 cm-1 or 558 nm) for the B‐X transition is close to the peak energy, and a significant absorption will result from a buildup in the concentration of X state HgCl in the course of exciting the laser media. This absorption is suggested as an explanation for the low extraction efficiencies observed for HgCl lasers. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Theoretical study of formation rates of rare‐gas halide trimers

    Page(s): 135 - 136
    Save to Project icon | PDF file iconPDF (146 KB)  

    A scarcity of information on the rare‐gas halide trimers makes detailed calculations of their formation rates from the excited rare‐gas halides impossible. However, we have developed an approximate method/model for determining these rate constants. Rate constants for reactions of possible interest for the KrF* and XeF* laser systems are calculated. These reactions are (1) KrF*+Rg+Rg′→KrRgF*+Rg′ and (2) XeF*+Rg+Rg′→XeRgF*+Rg′, where Rg, Rg′=Ar, Kr in Eq. (1) and Ne, Ar, Xe in Eq. (2). Results are compared with available experimental data. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Photoacoustic measurements of ion‐implanted and laser‐annealed GaAs

    Page(s): 137 - 139
    Save to Project icon | PDF file iconPDF (174 KB)  

    Photoacoustic techniques were developed for use as a rapid and sensitive diagnostic of crystalline disorder produced by ion implantation in gallium arsenide. With a 150‐keV silicon implant, doses as low as 1012 cm-2 were detectable. Recrystallization of ion‐implanted gallium arsenide by laser annealing is readily detected by the photoacoustic method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surfaces for radiative cooling: Silicon monoxide films on aluminum

    Page(s): 139 - 141
    Save to Project icon | PDF file iconPDF (287 KB)  

    Efficient radiative cooling is feasible with surfaces which radiate predominantly in the 8–13‐μm wavelength range, where the atmosphere emittance is low. The desired reflectance profile was approximated with 1.0 μm of SiO evaporated onto Al. It results from strong lattice absorption in SiO in conjunction with destructive interference. Refrigeration to 40 K below the ambient appears to be possible under suitable climatic conditions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Self‐aligned thin film structures with 1000 Å resolution

    Page(s): 141 - 143
    Save to Project icon | PDF file iconPDF (421 KB)  

    A two‐level e‐beam resist process is described which is capable of producing features under 1000 Å in size. The process is compatible with oblique evaporation technique so that high‐accuracy alignment can be obtained in multiple‐layer device structures. Tunnel junction structures with areas as small as 10-10 cm2 have been fabricated. The estimated capacitance for such junctions is ≪10-15 F. Such structures have application in low‐capacitance Josephson logic circuits. The process is also applicable to fabrication of submicron MOM diodes and other devices which can be made using a lift‐off technique. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Liquid crystal alignment on surfactant treated obliquely evaporated surfaces

    Page(s): 144 - 146
    Save to Project icon | PDF file iconPDF (270 KB)  

    We report observations on the alignment of nematic liquid crystals on surfaces of obliquely deposited silicon monoxide, with and without additional treatment with surfactant. The liquid crystals reported on are 4.4‐dihexylazoxybenzene and 4‐heptyl‐4’‐cyanobipheny. The surfactants used are N,N‐dimethyl‐N‐octadecyl‐3‐aminopropyltrimethoxysilyl chloride and plasma polymerized tetrafluoroethylene. While untreated silicon monoxide surfaces produce inclined alignment, with the liquid crystal director oriented in the same quadrant as the direction of deposition, it was found that treatment with surfactant can result in an inclined alignment away from the direction of deposition, with the director now oriented nearly perpendicular to the direction obtained in the absence of surfactant. A simple model to explain these observations is presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of oxygen concentration profiles in silicon crystals observed by scanning IR absorption using semiconductor laser

    Page(s): 147 - 148
    Save to Project icon | PDF file iconPDF (204 KB)  

    Concentration profiles of interstitial oxygen in silicon crystals were determined by scanning IR absorption using PbTe‐Pb0.82Sn0.18Te semiconductor laser with the wavelength of 9.04±0.02 μm. IR beam was collimated to be 200 μm in diameter. Czochralski‐grown crystals showed a local concentration fluctuation of about 1.8×1017 cm-3 from the average of 1.1×1018 cm-3. This fluctuation corresponds to an oxygen striation in the silicon crystal. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An integrated photoconductive detector and waveguide structure

    Page(s): 149 - 151
    Save to Project icon | PDF file iconPDF (287 KB)  

    A new photoconductive detector is described that uses the previously reported optical field effect transistor structure. The detector has good sensitivity (photoconductive gain of ∼5) and high speed (∼150 psec). Light was coupled to this detector via a 7059 glass over SiO2 waveguide. The overall coupling efficiency including losses in endfire coupling was about 40%. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 500‐MHz GaAs charge‐coupled device

    Page(s): 151 - 153
    Save to Project icon | PDF file iconPDF (282 KB)  

    The higher electron mobility in GaAs relative to silicon makes it possible to design an ultra‐high‐Speed charge‐coupled device. A buried‐channel Schottky barrier gate GaAs charge‐coupled device (CCD) is described which has been operated at up to 500 MHz clock frequency. The transit‐time‐limited upper clock frequency in this device is predicted to exceed 5 GHz. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measurements of the rectifying barrier heights of various rhodium silicides with n‐silicon

    Page(s): 153 - 155
    Save to Project icon | PDF file iconPDF (215 KB)  

    The barrier height of Schottky diodes formed with 〈111〉 and 〈100〉 n‐type silicon substrates and Rh, RhSi, Rh4S5, and Rh3Si4 have been determined by means of photoresponse, capacitance, and forward current‐voltage measurements. The results are compared to the results previously obtained with iridium, and with other plantinum related elements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Formation process of oxide precipitates in Czochralski‐grown silicon crystals

    Page(s): 156 - 158
    Save to Project icon | PDF file iconPDF (328 KB)  

    Swirl‐free silicon crystals were grown, and the relation between growth condition and oxide precipitates (1100 °C) has been studied by the Secco etching technique and x‐ray topography. It was found that precipitates are formed at very high densities in crystals which were grown by introducing temperature fluctuations during the growth. They are located in the seed side of a remelt boundary on which a new growth circle started after each remelting. These results are similar to those for swirl defects in float‐zoned crystals. It is proposed that the precipitates are originated from liquid drops which are formed in interface regions superheated by temperature fluctuations during the growth. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Solid‐phase growth of large aligned grains during scanned laser crystallization of amorphous Ge films on fused silica

    Page(s): 158 - 161
    Save to Project icon | PDF file iconPDF (413 KB)  

    Well‐aligned grains of dimensions up to 2–3×100 μm have been obtained by laser crystallization of amorphous Ge films on fused‐silica substrates. A theoretical model has been developed for the dynamics of the crystallization process, a solid‐phase transformation that is greatly accelerated by liberation of the latent heat of transformation, resulting in either periodic or runaway motion of the crystallization front. We believe that scanning of amorphous films with an energy beam of large aspect ratio may be developed into an effective process for preparing large‐grained or even single‐crystal sheets of Ge and other semiconductors, including Si and GaAs. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Elastic stiffness and thermal expansion coefficient of BN films

    Page(s): 161 - 163
    Save to Project icon | PDF file iconPDF (259 KB)  

    Room temperature stresses were found to be tensile for chemical vapor deposition films of the composition B2N and compressive for BN, with all films becoming more tensile with heating. Analyses of the stress‐temperature curves of identical films of BN deposited on two different substrate materials yield values of 1.3×1012 dynes/cm2 for the elastic stiffness parameter E/(1-ν) and 1.0 ppm/°C for the thermal expansion coefficient. This technique is of general applicability to thin films and it is believed to be the first practical (nondestructive) means of determining both the elastic stiffness parameter and thermal expansion coefficient of a film. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Polycrystalline silicon films deposited in a glow discharge at temperatures below 250 °C

    Page(s): 163 - 165
    Save to Project icon | PDF file iconPDF (316 KB)  

    Raman scattering, x‐ray diffraction and electron diffraction results show that thin films of silicon (ranging in thickness from a few hundred Å to 1 μm) prepared by chemical transport in low‐pressure hydrogen plasma at a temperature between 230 and 280 °C and a deposition rate of up to ∼0.5 Å sec-1, are polycrystalline. X‐ray diffraction and transmission electron microscopic data indicate crystallite sizes amounting to a few hundred Å. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Very high quantum efficiency GaSb mesa photodetectors between 1.3 and 1.6 μm

    Page(s): 165 - 167
    Save to Project icon | PDF file iconPDF (264 KB)  

    In this letter very high quantum efficiency GaSb mesa photodiodes with AlxGa1-xSb windows are reported for the first time. External quantum efficiencies (ηext) of ≃60% at zero bias and of ≃70% at -1 V near 1.3 μm have been obtained without antireflection coatings. More than 80% of the devices from several wafers exhibited ηext⩾50% at λ≃1.3 μm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Leakage current in InGaAsP avalanche photodiodes

    Page(s): 167 - 170
    Save to Project icon | PDF file iconPDF (294 KB)  

    The increased leakage current in InGaAsP APD’s near breakdown is found to be a rather uniform bulk property, not associated with conventional microplasmas, dislocations, or surface effects. Surface effects were eliminated by the fabrication of guard ring APD’s, but the increased leakage current persisted. Surface effects were further ruled out by a statistical study of the leakage current in a large sample of APD’s. The study shows conclusively that the leakage current is proportional to diode area, not perimeter. 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