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14 Jul 1997

Volume 71, Issue 2, pp. 151-293

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Wideband optical modulation via the magneto–optic interaction in a bismuth-lutetium-iron garnet film

A. Prabhakar and D. D. Stancil

Appl. Phys. Lett. 71, 151 (1997); http://dx.doi.org/10.1063/1.119487 (3 pages) | Cited 11 times

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Optical modulation with a bandwidth of about 3 GHz centered at 5.75 GHz was observed in a thin film of [BiLu]3Fe5O12 using the magneto-optical interaction. A microstrip transducer was placed in contact with the film and TM polarized optical guided modes were excited beneath and parallel to the transducer. The TM→TE mode conversion was measured as a function of the angle between an in-plane field, of up to 100 Oe, and the optical beam. The bandwidth of the modulation was limited by the microwave components used in the external circuit. The experiments qualitatively agree with a simple model that describes a modulation of the optical beam by a nonresonant precession of the magnetization about an equilibrium. © 1997 American Institute of Physics.
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75.50.Gg Ferrimagnetics
78.66.Nk Insulators
78.20.Ls Magneto-optical effects
42.79.Hp Optical processors, correlators, and modulators
75.70.Ak Magnetic properties of monolayers and thin films
85.70.Sq Magnetooptical devices

Self-stabilization of a continuous wave multimode green laser due to antiphase dynamics

V. I. Ustyugov, O. A. Orlov, M. M. Khaleev, G. E. Novikov, E. A. Viktorov, and Paul Mandel

Appl. Phys. Lett. 71, 154 (1997); http://dx.doi.org/10.1063/1.119488 (3 pages) | Cited 8 times

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The stability of a diode pumped Nd:YAG laser with intracavity KTP in an L-shaped cavity is studied. The mirror which connects the two cavity arms is a dielectric which also acts as a partial polarizer. This design provides a high level of stability for the total output power, despite the instability of the separate modes: separate modes are chaotic with large amplitude noise while the total output displays reduced noise below 1% rms. A model based on the Jones matrices is studied numerically. It shows antiphase and clustering, in excellent qualitative agreement with the experimental data. © 1997 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Mi Dynamical laser instabilities; noisy laser behavior
42.79.Bh Lenses, prisms and mirrors

Comparison of experimental and theoretical GaInP quantum well gain spectra

W. W. Chow, P. M. Smowton, P. Blood, A. Girndt, F. Jahnke, and S. W. Koch

Appl. Phys. Lett. 71, 157 (1997); http://dx.doi.org/10.1063/1.119489 (3 pages) | Cited 39 times

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A microscopic analysis of experimental GaInP quantum well gain spectra is presented for a wide range of excitation. A consistent treatment of carrier collision effects, at the level of quantum kinetic theory in the Markovian limit, is found to be necessary for agreement with experiment. © 1997 American Institute of Physics.  
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85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Self-consistent eigenmode analysis of the dielectrically apertured Fabry–Perot microcavity

D. G. Deppe and Q. Deng

Appl. Phys. Lett. 71, 160 (1997); http://dx.doi.org/10.1063/1.119490 (3 pages) | Cited 4 times

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Analysis is presented to calculate the eigenmode of a Fabry–Perot microcavity containing an optically thin dielectric aperture. The treatment yields the eigenmode field distribution, frequency, and threshold susceptibility. It is also suggested that self-focusing phenomena in large area vertical-cavity surface-emitting lasers can arise due to aperture formation by the complex susceptibility of a quantum well active region. © 1997 American Institute of Physics.
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42.55.Sa Microcavity and microdisk lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.55.Px Semiconductor lasers; laser diodes
42.79.Bh Lenses, prisms and mirrors

High pressure discharges in cavities formed by microfabrication techniques

Babar A. Khan, David A. Cammack, Ronald D. Pinker, and Jacqueline Racz

Appl. Phys. Lett. 71, 163 (1997); http://dx.doi.org/10.1063/1.120412 (3 pages) | Cited 1 time

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High pressure discharges are the basis of small high intensity light sources. In this work, we demonstrate the formation of high pressure discharges, in cavities formed by applying micromachining and integrated circuit techniques to quartz substrates. Cavities containing varying amounts of mercury and argon were fabricated to obtain high pressure discharges. A high pressure mercury discharge was formed in the electrodeless cavities by exciting them with a microwave source, operating at 2.45 GHz and in the electroded cavities by applying a dc voltage. The contraction of the discharge into a high pressure arc was observed. A broad emission spectrum due to self-absorption and collisions between excited atoms and normal atoms, typical of high pressure mercury discharges, was measured. The light output and efficacy increased with increasing pressure. The measured voltage was used to estimate the pressure within the electroded cavities, which is as high as 127 atm for one of the two cavities discussed in this work. Efficacies over 40 lumens per watt were obtained for the electrodeless cavities and over 50 lm/W for the electroded cavities. © 1997 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
42.72.Bj Visible and ultraviolet sources

X-ray yields from Xe clusters heated by short pulse high intensity lasers

T. Ditmire, R. A. Smith, R. S. Marjoribanks, G. Kulcsár, and M. H. R. Hutchinson

Appl. Phys. Lett. 71, 166 (1997); http://dx.doi.org/10.1063/1.119491 (3 pages) | Cited 45 times

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We have examined the absolute yield of keV x-rays emitted from gaseous plasmas created by the intense irradiation of large Xe clusters. We find that >10 μJ of x rays with photon energies above 1 keV are produced from clustering Xe gas targets when heated by 250 mJ, 2 ps laser pulses at an intensity of ∼ 1017 W/cm2. The yields show strong laser intensity dependence and variation with Xe cluster size. © 1997 American Institute of Physics.
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36.40.Mr Spectroscopy and geometrical structure of clusters
42.55.Vc X- and γ-ray lasers
32.30.Rj X-ray spectra
52.70.La X-ray and γ-ray measurements
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Apertureless near-field optical microscopy with differential and close-proximity detection

Kenji Fukuzawa and Yuriko Tanaka

Appl. Phys. Lett. 71, 169 (1997); http://dx.doi.org/10.1063/1.119492 (3 pages) | Cited 8 times

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A new method of apertureless near-field optical microscopy that combines laterally differential detection with close-proximity detection has been developed. The laterally differential detection allows the light scattered from the probe apex to be distinguished from the background light. The close-proximity detection is done using a microfabricated photosensitive cantilever; it is thought to be a form of heterodyne detection, which provides a high signal level. This method makes it possible to detect the light scattered from the probe apex, which depends on the coupling between the probe apex dipole and the sample feature dipole. © 1997 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes

5 W continuous wave power, 0.81-μm-emitting, Al-free active-region diode lasers

J. K. Wade, L. J. Mawst, D. Botez, R. F. Nabiev, and M. Jansen

Appl. Phys. Lett. 71, 172 (1997); http://dx.doi.org/10.1063/1.119528 (3 pages) | Cited 11 times

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High power, 0.81-μm-emitting, semiconductor diode lasers are used as pump sources for Nd:YAG solid-state lasers. Devices (1-mm-long) consisting of a InGaAsP/In0.5(Ga0.9Al0.1)0.5P/In0.5(Ga0.5Al0.5)0.5P laser structure provide a threshold-current density, Jth, of 290 A/cm2 and a relatively high threshold-current characteristic temperature, T0 (140 K). Uncoated diode lasers (1.2-mm-long) have a maximum continuous wave output power of 5 W (both facets) at 20 °C. The internal power density at catastrophic optical mirror damage (COMD), mathCOMD, is determined to be 9.1 MW/cm2; that is, 1.8 times that for GaAs-active layer, Al-free, uncoated devices. Coated, InGaAsP-active devices are expected to have mathCOMD = 18 MW/cm2, more than twice the mathCOMD of AlGaAs-active, 0.81-μm-emitting devices with the same emitting aperture. Therefore, 0.81-μm-emitting, InGaAsP-active diode lasers should operate reliably at powers at least twice those of AlGaAs-based devices with the same contact-stripe geometry. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.79.Bh Lenses, prisms and mirrors

Radiation hardening of pure-silica-core optical fibers: Reduction of induced absorption bands associated with self-trapped holes

David L. Griscom

Appl. Phys. Lett. 71, 175 (1997); http://dx.doi.org/10.1063/1.119493 (3 pages) | Cited 14 times

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Visible/near-IR-range radiation hardening of a pair of low-OH/low-Cl silica-core optical fibers has been accomplished by γ-ray preirradiation at 27 C to a dose of 13 MGy(Si) at a dose rate of 1 Gy(Si)/s in the dark. Reirradiation under identical conditions three months later demonstrated a 25-fold decrease in the initially induced intensities of the prominent radiation-induced bands centered near 660 and 760 nm and comparable decreases in weaker bands at longer and shorter wavelengths. Spectral changes observed in the wavelength regime 400–1000 nm upon quenching the irradiated fibers to 77 K have revealed the likely copresence, even at room temperature, of a previously reported “low temperature infrared absorption” which peaks near 1600 nm. Based on this insight, induced losses at 1550 nm have been extrapolated from the present data. It is argued that self-trapped holes are most likely responsible for most of the metastable induced absorption bands in the range ∼ 400–2000 nm. © 1997 American Institute of Physics.
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42.81.Dp Propagation, scattering, and losses; solitons
78.40.Ha Other nonmetallic inorganics
78.30.Hv Other nonmetallic inorganics
61.80.Ed γ-ray effects
81.40.Gh Other heat and thermomechanical treatments
81.40.Tv Optical and dielectric properties related to treatment conditions

Coupled-cavity resonant photodetectors for high-performance wavelength demultiplexing applications

S. Y. Hu, E. R. Hegblom, and L. A. Coldren

Appl. Phys. Lett. 71, 178 (1997); http://dx.doi.org/10.1063/1.119523 (3 pages) | Cited 4 times

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A new coupled-cavity resonant photodetector structure is studied to provide a flat-topped passband with steep skirts in the photoresponse. The idea is to add a low-loss cavity that is optically coupled to the absorptive cavity via an intermediate mirror. Experimental reflection spectra confirm this coupling effect. Modeling for an InGaAs/GaAs/AlGaAs design reveals that this new coupled-cavity structure will be able to show a 22 dB channel rejection ratio even when the optical channel spacing is as narrow as 2 nm. In addition, the design and processing tolerances for cavity-mode adjustment are also addressed. © 1997 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
85.30.De Semiconductor-device characterization, design, and modeling
42.79.Bh Lenses, prisms and mirrors

Anomalous longitudinal mode hops in GaAs/AlGaAs distributed Bragg reflector lasers

Daniel Hofstetter and Hans P. Zappe

Appl. Phys. Lett. 71, 181 (1997); http://dx.doi.org/10.1063/1.119494 (3 pages) | Cited 1 time

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We investigate normal and anomalous longitudinal mode hops in GaAs/AlGaAs-based distributed Bragg reflector (DBR) lasers; anomalous mode hops are defined as those which move toward shorter wavelengths with increasing temperature, which is unexpected. The two-section DBR lasers discussed in this letter, consisting of a gain section and an unpumped Bragg reflector, typically exhibit one mode hop in a 10 K temperature range. Although the longer wavelength modes are expected to start lasing when raising device temperature, occasional mode hops to a shorter wavelength are seen. We derive a model for temperature-dependent wavelength tuning, with which the overheating of the gain section is described empirically. This model allows an accurate numerical simulation of both kinds of temperature-induced longitudinal mode hops. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
81.05.Ea III-V semiconductors
42.60.Fc Modulation, tuning, and mode locking

A new protective AlN film for organic photoconductors

X. S. Miao, Y. C. Chan, and E. Y. B. Pun

Appl. Phys. Lett. 71, 184 (1997); http://dx.doi.org/10.1063/1.119495 (3 pages) | Cited 8 times

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AlN film with high transmissivity was deposited onto organic photoconductor (OPC) surface and the surface hardness was increased by between 31.9% and 61.5%, and the surface roughness was also decreased. The electrophotographic properties of the OPC coated with AlN film were also improved, thus confirming the suitability of AlN film for enhancing the operating life of OPC. © 1997 American Institute of Physics.
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81.40.Pq Friction, lubrication, and wear
72.40.+w Photoconduction and photovoltaic effects
42.79.Wc Optical coatings
62.20.Qp Friction, tribology, and hardness
81.65.-b Surface treatments
68.35.Gy Mechanical properties; surface strains
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
68.35.B- Structure of clean surfaces (and surface reconstruction)
07.68.+m Photography, photographic instruments; xerography
78.66.Fd III-V semiconductors

Photodarkening in 4-(N,N-diethylamino)-β-nitrostyrene solutions

T. Yanagawa and H. Kanbara

Appl. Phys. Lett. 71, 187 (1997); http://dx.doi.org/10.1063/1.119496 (3 pages)

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Photodarkening is reported in 4-(N,N-diethylamino)-β-nitrostyrene solutions. The photodarkening is due to the formation of new absorption bands and is thought to be a photochemical effect of the structural changes. In degenerate four-wave mixing, a resonant effect is observed around the new absorption bands but the fast response behavior does not change. After darkening, the excitation spectrum becomes complicated, which implies a multipath decay that may show the fast response in the resonant region. The solvent and concentration dependence of the darkening property is also reported. © 1997 American Institute of Physics.
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78.20.-e Optical properties of bulk materials and thin films
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation

Off-axis reflection zone plate for quantitative soft x-ray source characterization

T. Wilhein, D. Hambach, B. Niemann, M. Berglund, L. Rymell, and H. M. Hertz

Appl. Phys. Lett. 71, 190 (1997); http://dx.doi.org/10.1063/1.119497 (3 pages) | Cited 21 times

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A compact system for high-resolution spectroscopy and quantitative photon flux and brilliance measurements of pulsed soft x-ray sources is described. The calibrated system combines a novel elliptical off-axis reflection zone plate with charge-coupled device detection for simultaneous spectral and spatial measurements. Experiments on a water-window droplet-target laser-plasma source demonstrate λ/Δλ⩾1000 spectral resolution and absolute flux and brilliance measurements. © 1997 American Institute of Physics.
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29.30.Kv X- and γ-ray spectroscopy
07.85.Nc X-ray and γ-ray spectrometers
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors

Temperature dependent lasing characteristics of multi-stacked quantum dot lasers

Hajime Shoji, Yoshiaki Nakata, Kohki Mukai, Yoshihiro Sugiyama, Mitsuru Sugawara, Naoki Yokoyama, and Hiroshi Ishikawa

Appl. Phys. Lett. 71, 193 (1997); http://dx.doi.org/10.1063/1.120426 (3 pages) | Cited 46 times

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Temperature dependence of self-formed quantum dot lasers with a multi-stacked dot layer has been investigated in detail. Lasers oscillating at different subbands exhibit different behaviors against temperature change both in the spectral characteristics and the threshold current. A discontinuous shift of lasing wavelength from the second subband to the ground state is observed with lowering temperature, which is strongly related to emission efficiency of quantum dots and thermal excitation of carriers to higher-order subbands. High characteristic temperature over 300 K has been achieved in a laser with high-reflection coating on both facets in the temperature range 60–200 K. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
73.20.At Surface states, band structure, electron density of states

Porous silicon lateral superlattices

G. Lérondel, R. Romestain, J. C. Vial, and M. Thönissen

Appl. Phys. Lett. 71, 196 (1997); http://dx.doi.org/10.1063/1.119498 (3 pages) | Cited 28 times

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Lateral superlattices in porous silicon layers have been generated. Using the photosensitivity of the etching process, periodic stripes are formed not only on the surface but also in the depth of the layer. The modulation depth depends on the illumination wavelength. The periodicity is obtained from the interference pattern of two laser beams, and can be easily modified by changing the wavelength or the incidence angles of the beams. The samples formed by this procedure were characterized by light diffraction. Two-dimensional structures can also be obtained by rotating the sample or by interference of four laser beams. This kind of in-depth lithography and the resulting low-cost fabrication of gratings out of porous silicon offer a wide range of potential applications in integrated optics and photonics. © 1997 American Institute of Physics.
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81.05.Cy Elemental semiconductors
81.05.Rm Porous materials; granular materials
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.80.Cw Elemental semiconductors
85.40.Hp Lithography, masks and pattern transfer
73.61.Cw Elemental semiconductors

An electrically controlled Bragg reflector integrated in a rib silicon on insulator waveguide

A. Cutolo, M. Iodice, A. Irace, P. Spirito, and L. Zeni

Appl. Phys. Lett. 71, 199 (1997); http://dx.doi.org/10.1063/1.119499 (3 pages) | Cited 21 times

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In this letter, we present a novel structure for light amplitude modulation based on a lateral p-i-n diode combined with a Bragg reflector which transforms the phase shift induced by the plasma dispersion effect in the intrinsic region of the diode into a voltage controlled variation of the reflectivity of the Bragg mirror. Numerical simulations show a modulation depth of 50% achieved in about 12 ns with a power dissipation of 4.0 mW and an insertion loss of 1.0 dB. The device is demonstrated to be very attractive in terms of power dissipation as compared to a Mach–Zehnder interferometer occupying the same area on chip. © 1997 American Institute of Physics.
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42.65.Wi Nonlinear waveguides
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
85.60.Bt Optoelectronic device characterization, design, and modeling
42.79.Hp Optical processors, correlators, and modulators

Unoccupied molecular orbital states of tris (8-hydroxy quinoline) aluminum: Observation and dynamics

M. Probst and R. Haight

Appl. Phys. Lett. 71, 202 (1997); http://dx.doi.org/10.1063/1.119500 (3 pages) | Cited 28 times

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Electrons photoexcited into the normally unoccupied states of vacuum deposited thin films of tris (8-hydroxy quinoline) aluminum (Alq) have been studied with excite-probe harmonic laser photoemission. Both valence and transiently excited empty states are observed. A surface recombination velocity of 75±30 cm/s has been determined. © 1997 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
78.55.Kz Solid organic materials
78.66.Qn Polymers; organic compounds
73.25.+i Surface conductivity and carrier phenomena

Distributed–feedback, tunable Ce3+-doped colquiriite lasers

Joseph F. Pinto and Leon Esterowitz

Appl. Phys. Lett. 71, 205 (1997); http://dx.doi.org/10.1063/1.119501 (3 pages) | Cited 6 times

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Distributed-feedback (dfb) laser oscillation is reported in Ce3+-doped LiSrAlF6 (LiSAF). Tunable operation of the Ce3+:LiSAF dfb laser is achieved in the ultraviolet wavelength region from 289 to 293 nm. At the peak emission wavelength of 290 nm, dfb lasing linewidths are less than the 1 Å resolution limit of the 1 m spectrometer. © 1997 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Fc Modulation, tuning, and mode locking

On the use of dust plasma acoustic waves for the diagnostic of nanometer-sized contaminant particles in plasmas

U. Kortshagen

Appl. Phys. Lett. 71, 208 (1997); http://dx.doi.org/10.1063/1.119502 (3 pages) | Cited 6 times

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During the phase of dust nucleation in plasma enhanced chemical vapor deposition systems, nanometer-sized dust particles appear in large concentrations. The dispersion characteristics of dust acoustic waves in such a plasma during the nucleation phase is analyzed. It is shown that the dispersion properties of the dust acoustic wave depend sensitively on the particle size. It is proposed to use dust acoustic waves as a novel particle size diagnostic for nanometer-sized particles. © 1997 American Institute of Physics.
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52.25.Vy Impurities in plasmas
52.35.-g Waves, oscillations, and instabilities in plasmas and intense beams
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
52.70.-m Plasma diagnostic techniques and instrumentation
82.70.-y Disperse systems; complex fluids

Off-axis holography of laser-induced shock wave targets

M. Werdiger, S. Eliezer, Z. Henis, B. Arad, Y. Horovitz, R. Shpitalnik, and S. Maman

Appl. Phys. Lett. 71, 211 (1997); http://dx.doi.org/10.1063/1.120411 (2 pages) | Cited 3 times

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Shock waves of the order of hundreds of kilobars are produced in a tin foil 50 μm thick by a Nd:YAG laser system with a wavelength of 1.06 μm, pulse width of 7 ns [full width at half-maximum (FWHM)] and irradiance in the range (1.4–2.4)×1013 W/cm2, focused to a spot of 200 μm. Off-axis holographic measurements of the target, after 0.5 and 1 μs from the shock arrival, are reported. The hologram is produced by backscattering of a pulse, 6.5 ns (FWHM) of green laser light, from the ejected material from the target. © 1997 American Institute of Physics.
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42.40.My Applications
47.40.Nm Shock wave interactions and shock effects
79.20.Ds Laser-beam impact phenomena

Controlled vertical manipulation of single CO molecules with the scanning tunneling microscope: A route to chemical contrast

L. Bartels, G. Meyer, and K.-H. Rieder

Appl. Phys. Lett. 71, 213 (1997); http://dx.doi.org/10.1063/1.119503 (3 pages) | Cited 84 times

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A reliable procedure for controlled vertical transfer of single CO molecules between a Cu(111) surface and a scanning tunneling microscope tip and vice versa is demonstrated. It is shown that with a tip having a single CO molecule at its apex, chemical contrast is achieved allowing distinction of adsorbed CO molecules and oxgen atoms, which look very similar to the bare metal tip. © 1997 American Institute of Physics.
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07.79.Cz Scanning tunneling microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
87.64.Dz Scanning tunneling and atomic force microscopy

Photophysical and photochemical investigations of fullerene presence in amorphous hydrogenated carbon films

J. Q. Chen, D. L. Meeker, and N. N. Barashkov

Appl. Phys. Lett. 71, 216 (1997); http://dx.doi.org/10.1063/1.119504 (3 pages) | Cited 3 times

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The plasma-enhanced chemical vapor deposition system was used to grow amorphous hydrogenated carbon films deposited on silicon substrates. Extracts of the films were obtained by treatment with boiling cyclohexane solvent. The absorption spectra of these extracts showed the existence of small quantities of fullerenes. Using the molar extinction coefficient of C60 in cyclohexane, the mass of fullerenes in the films was estimated to be about 0.019 mg. C60 induced fluorescence quenching of anthracene was also observed. Additional evidence for the presence of fullerenes was based on their capability to accelerate the photo-oxidation of anthracene through the generation of singlet oxygen with a high quantum yield under ultraviolet irradiation. © 1997 American Institute of Physics.
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68.55.Nq Composition and phase identification
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
78.66.Tr Fullerenes and related materials
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
78.55.Hx Other solid inorganic materials
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Microstructure of sputtered TiN on Al

D. J. Eaglesham, J. E. Bower, M. A. Marcus, M. Gross, and S. Merchant

Appl. Phys. Lett. 71, 219 (1997); http://dx.doi.org/10.1063/1.119525 (3 pages) | Cited 13 times

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We use electron microscopy and x-ray diffraction to study the microstructure of TiN deposited on Al. In contrast to previous work, we show that the TiN has a large (≈1 μm) grain size arising from its epitaxial orientation on the underlying Al. Within a single grain, the TiN has a heavily voided columnar structure that closely mimics the appearance of fine grains. The within-grain columnar structure arises from the usual shadowing mechanism for sputtered films, and has a weak dependence on the deposition temperature. © 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.72.Qq Microscopic defects (voids, inclusions, etc.)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Cd Deposition by sputtering

Direct absolute measurements of the two-dimensional elastic constants in smectic C∗ liquid crystal films

Yves Galerne, Isabelle Poinsot, and Daniel Schaegis

Appl. Phys. Lett. 71, 222 (1997); http://dx.doi.org/10.1063/1.119505 (3 pages) | Cited 4 times

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The orientational elastic constants of free-standing films in a tilted smectic phase are directly measured in absolute units with a new experimental method similar to light scattering in the heterodyne regime. Basically, the amplitude of the thermodynamically excited orientational fluctuations, which modulate polarized light, is measured in the direct space by means of a microscope and a video camera connected to a microcomputer. Then, with a Fourier transform, we go into the reciprocal space and deduce the two-dimensional bend and splay elastic constants of the film in a range of wave vectors simultaneously. The method, which only needs light experimental means, is simple, fast, and accurate. It can be particularly helpful in the ferroelectric smectic C∗ liquid crystals for determining the elastic constants and indirectly the ferroelectric polarizations, without problems for orienting the samples. © 1997 American Institute of Physics.
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61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
62.10.+s Mechanical properties of liquids
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals
78.35.+c Brillouin and Rayleigh scattering; other light scattering
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