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26 Aug 2002

Volume 81, Issue 9, pp. 1543-1743

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Intersubband electroluminescence from Si/SiGe cascade emitters at terahertz frequencies

S. A. Lynch, R. Bates, D. J. Paul, D. J. Norris, A. G. Cullis, Z. Ikonic, R. W. Kelsall, P. Harrison, D. D. Arnone, and C. R. Pidgeon

Appl. Phys. Lett. 81, 1543 (2002); http://dx.doi.org/10.1063/1.1501759 (3 pages) | Cited 47 times

Online Publication Date: 19 August 2002

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The quantum cascade laser provides one possible method of realizing high efficiency light emitters in indirect band gap materials such as silicon. Electroluminescence results from Si/SiGe quantum cascade emitters are presented demonstrating edge emission from heavy-hole to heavy-hole transitions and light-hole to heavy-hole transitions. In surface-normal emission, only light-hole to heavy-hole electroluminescence is observed as predicted by theory. Intersubband emission is demonstrated at 2.9 THz (103 μm wavelength), 8.9 THz (33.7 μm), and 16.2 THz (18.5 μm) from the Si/SiGe quantum cascade heterostructures. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.60.Fi Electroluminescence
42.60.By Design of specific laser systems
78.66.Li Other semiconductors
78.66.Db Elemental semiconductors and insulators

Lateral-cavity spectral hole burning in quantum-dot lasers

D. Ouyang, R. Heitz, N. N. Ledentsov, S. Bognár, R. L. Sellin, Ch. Ribbat, and D. Bimberg

Appl. Phys. Lett. 81, 1546 (2002); http://dx.doi.org/10.1063/1.1503852 (3 pages) | Cited 12 times

Online Publication Date: 19 August 2002

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Spectral hole burning effects are observed as strong spectral intensity modulations in the emission spectra of broad and narrow stripe quantum-dot lasers with ridge waveguide. The modulation is attributed to lateral-cavity resonances burning holes in the inhomogeneously broadened spectral gain profile of the quantum dots. Lateral cavity engineering is expected to be crucial for optimizing quantum-dot laser performance and for potential realizing of wavelength-stabilized devices. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Wi Nonlinear waveguides
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.50.Hz Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift
42.82.Et Waveguides, couplers, and arrays

Wavelength demultiplexers based on the superprism phenomena in photonic crystals

K. B. Chung and S. W. Hong

Appl. Phys. Lett. 81, 1549 (2002); http://dx.doi.org/10.1063/1.1503869 (3 pages) | Cited 28 times

Online Publication Date: 19 August 2002

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We numerically analyze microscale wavelength-division-demultiplexing devices based on superprism phenomenon and waveguiding in photonic crystals. A few simple wavelength demultiplexers, which are composed of two photonic crystal structures that have different band structures and are in close contact with each other, are designed and simulated with the finite-difference time-domain method. It is found that depending on frequency, each demultiplexer diffracts incident waves in different directions, and couples them into different output photonic-crystal waveguides with low cross talk. © 2002 American Institute of Physics.
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42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.70.Qs Photonic bandgap materials

Simple method to diagnose the performance of electroabsorption modulators on InP using optical low-coherence reflectometry

E. V. K. Rao, Y. Gottesman, and J. G. Provost

Appl. Phys. Lett. 81, 1552 (2002); http://dx.doi.org/10.1063/1.1503170 (3 pages) | Cited 2 times

Online Publication Date: 19 August 2002

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This letter describes a judicious implication of optical low-coherence reflectometry (OLCR) measurements to evaluate the principal characteristics of an electroabsorption modulator with passive sections on either ends of its active layer fabricated on an InP substrate. We show here that careful monitoring of the reflections at the transition regions (passive to active and vice versa), and also transmission of a broadband OLCR ( ∼ 55 nm wide and centered at ∼ 1.56 μm) probe light as a function of applied reverse bias, permit a nearly complete assessment of the device. For example, in addition to assessing the quality of the transition regions, such a study further leads to the determination of the optimal operation wavelength and also the modulation depth of the device. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.79.Hp Optical processors, correlators, and modulators
78.20.Jq Electro-optical effects

Fabrication of linear colloidal structures for microfluidic applications

A. Terray, J. Oakey, and D. W. M. Marr

Appl. Phys. Lett. 81, 1555 (2002); http://dx.doi.org/10.1063/1.1503176 (3 pages) | Cited 33 times

Online Publication Date: 19 August 2002

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In this letter, an optical microfabrication and actuation method for the creation of microfluidic structures is described. In this approach, an optical trap is used to position and polymerize colloidal microspheres into linear structures to create particle or cell directing devices within microfluidic channel networks. To demonstrate the utility of these structures, two microscale particulate valves are shown, a passive design that restricts particulate flow in one direction and another design that directs particulate flow to one of two exit channels. © 2002 American Institute of Physics.
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47.85.Np Fluidics
81.16.Ta Atom manipulation
47.85.L- Flow control
82.70.Dd Colloids

Electro-optic detection of subwavelength terahertz spot sizes in the near field of a metal tip

N. C. J. van der Valk and P. C. M. Planken

Appl. Phys. Lett. 81, 1558 (2002); http://dx.doi.org/10.1063/1.1503404 (3 pages) | Cited 62 times

Online Publication Date: 19 August 2002

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We report on a method to obtain a subwavelength resolution in terahertz time-domain imaging. In our method, a sharp copper tip is used to locally distort and concentrate the THz electric field. The distorted electric field, present mainly in the near field of the tip, is electro-optically measured in an (100) oriented GaP crystal. By raster scanning the tip along the surface of the crystal, we find the smallest THz spot size of 18 μm for frequencies from 0.1 to 2.5 THz. For our peak frequency of 0.15 THz, this corresponds to a resolution of λ/110. Our setup has the potential to reach a resolution down to a few μm. © 2002 American Institute of Physics.
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78.20.Jq Electro-optical effects
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Multiple resonances in microdisk lasers of π-conjugated polymers

R. C. Polson, Z. V. Vardeny, and D. A. Chinn

Appl. Phys. Lett. 81, 1561 (2002); http://dx.doi.org/10.1063/1.1502002 (3 pages) | Cited 15 times

Online Publication Date: 19 August 2002

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We have fabricated microdisk lasers from π-conjugated polymers that show multiline emission spectrum upon optical excitation. Using Fourier transform analysis, each emission line is assigned integer to an interger Bessel function that helps to estimate the field distribution inside the photoexcited polymer microdisk. We found that the microdisk can sustain two different laser modes with different, though complementary, field distributions and that the index of refraction decreases with increasing excitation intensity. © 2002 American Institute of Physics.
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42.55.Sa Microcavity and microdisk lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Voltage-controlled wavelength conversion by terahertz electro-optic modulation in double quantum wells

M. Y. Su, S. G. Carter, M. S. Sherwin, A. Huntington, and L. A. Coldren

Appl. Phys. Lett. 81, 1564 (2002); http://dx.doi.org/10.1063/1.1502441 (3 pages) | Cited 21 times

Online Publication Date: 19 August 2002

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An undoped double quantum well (DQW) was driven with a terahertz (THz) electric field of frequency ωTHz polarized in the growth direction, while simultaneously illuminated with a near-infrared (NIR) laser at frequency ωNIR. The intensity of NIR upconverted sidebands ωsideband = ωNIR+ωTHz was maximized when a dc voltage applied in the growth direction tuned the excitonic states into resonance with both the THz and NIR fields. There was no detectable upconversion far from resonance. The results demonstrate the possibility of using gated DQW devices for all-optical wavelength shifting between optical communication channels separated by up to a few THz. © 2002 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Hp Optical processors, correlators, and modulators
42.79.Nv Optical frequency converters
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

Photorefractive x-ray imaging

D. Berben, B. Andreas, and K. Buse

Appl. Phys. Lett. 81, 1567 (2002); http://dx.doi.org/10.1063/1.1502009 (3 pages) | Cited 2 times

Online Publication Date: 19 August 2002

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Photorefractive effects that are affected by x-rays are used to design an x-ray imaging system with outstanding spatial resolution. An elementary holographic reflection grating is recorded in a photorefractive iron-doped lithium niobate crystal. The x-rays yield a conductivity pattern that erases the hologram locally. The diffracted visible light now bears the x-ray image. In first experiments, structures of 25 μm size are easily resolved with a dose of 90 Gray and a signal-to-noise ratio of 6. The detector is fully reversible, has a logarithmic response, and is able to operate for hard x rays (>100 keV). © 2002 American Institute of Physics.
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41.50.+h X-ray beams and x-ray optics
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.40.Eq Holographic optical elements; holographic gratings
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Fuzzy-junction organic light-emitting devices

C.-W. Chen, T.-Y. Cho, C.-C. Wu, H.-L. Yu, and T.-Y. Luh

Appl. Phys. Lett. 81, 1570 (2002); http://dx.doi.org/10.1063/1.1502912 (3 pages) | Cited 15 times

Online Publication Date: 19 August 2002

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A “fuzzy-junction” organic light-emitting device (OLED) containing a graded organic–organic interface is reported. Such graded junction is effectively produced utilizing interdiffusion through an ultrathin interfacial fusing layer sandwiched between two functional layers. With a glass transition temperature (Tg) lower than remaining layers, this fusing layer permits smooth interdiffusion and mixing of neighboring layers by annealing above its Tg. With appropriate material combinations, fuzzy-junction OLEDs thus prepared exhibit both reduced voltage and enhanced emission efficiency in comparison with conventional abrupt-junction devices. As an instance, a green fluorescent OLED with such fuzzy junction shows a high peak power efficiency of ∼20 lm/W, substantially higher than ∼14 lm/W of a corresponding abrupt-junction device. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
68.35.Fx Diffusion; interface formation
61.72.Cc Kinetics of defect formation and annealing

Parametric and cascaded parametric interactions in a quasiperiodic optical superlattice

Y. Du, S. N. Zhu, Y. Y. Zhu, P. Xu, C. Zhang, Y. B. Chen, Z. W. Liu, N. B. Ming, X. R. Zhang, F. F. Zhang, and S. Y. Zhang

Appl. Phys. Lett. 81, 1573 (2002); http://dx.doi.org/10.1063/1.1502007 (3 pages) | Cited 9 times

Online Publication Date: 19 August 2002

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Quasi-phase-matching optical parametric and cascaded parametric processes in a two-component quasiperiodic superlattice were studied in theory and experiment. This letter demonstrates how to obtain red at 666 nm and blue at 443 nm simultaneously from the superlattice using a 532 nm laser as a pump through these two processes mentioned above. The result confirms that some nonlinear frequency conversion processes occurring in a high-dimension χ(2) nonlinear photonic crystal may be efficiently achieved in such a one-dimension quasiperiodic optical superlattice. © 2002 American Institute of Physics.
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78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
42.65.-k Nonlinear optics
42.65.Yj Optical parametric oscillators and amplifiers
42.79.Wc Optical coatings
42.70.Qs Photonic bandgap materials

Splitting of the focal spot of a high numerical-aperture objective in free space

James W. M. Chon, Xiaosong Gan, and Min Gu

Appl. Phys. Lett. 81, 1576 (2002); http://dx.doi.org/10.1063/1.1501442 (3 pages) | Cited 24 times

Online Publication Date: 19 August 2002

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Reported in this letter is a phenomenon that the focal spot of a high numerical-aperture objective in free space can split into two spots if a ring beam is used for illumination. Diffraction by a high numerical-aperture objective results in a depolarization such that the diffracted field in the focal region includes not only a component with the same polarization as the incident beam, but also orthogonal and longitudinal components. The use of a ring beam enhances the relative contribution from the longitudinal component. As a result, a single focal spot splits into two spots along the incident polarization direction. It is revealed theoretically that for an objective of given numerical aperture there is a threshold of the central obstruction size of a ring beam for the appearance of a two-peak focus. © 2002 American Institute of Physics.
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42.79.Bh Lenses, prisms and mirrors
42.25.Fx Diffraction and scattering
42.25.Ja Polarization

Generation of low-frequency components due to phase-amplitude modulation of subcycle far-infrared pulses in near-field diffraction

Oleg Mitrofanov, L. N. Pfeiffer, and K. W. West

Appl. Phys. Lett. 81, 1579 (2002); http://dx.doi.org/10.1063/1.1503871 (3 pages) | Cited 9 times

Online Publication Date: 19 August 2002

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We observe carrier phase dependent generation of low-frequency spectral components in the near-field zone of a subwavelength aperture illuminated by subcycle far-infrared (terahertz) pulses. Diffraction induced π/2-phase shift of the pulse carrier results in the spectral intensity variation of the low-frequency components. The effect appears only if the pulse duration is shorter than the period of the carrier oscillation. © 2002 American Institute of Physics.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.79.Hp Optical processors, correlators, and modulators

Widely tunable light-emitting diodes by Stark effect in forward bias

N. Le Thomas, N. T. Pelekanos, Z. Hatzopoulos, E. Aperathitis, and R. Hamelin

Appl. Phys. Lett. 81, 1582 (2002); http://dx.doi.org/10.1063/1.1503403 (3 pages) | Cited 4 times

Online Publication Date: 19 August 2002

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By band gap engineering of the active region of a light-emitting diode, we were able to induce, in forward bias, large space-charge electric fields that generated Stark shifts over 100 nm in the 900 nm spectral region. These shifts are analyzed in terms of inhomogeneous carrier distribution throughout the active region. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.21.Fg Quantum wells
78.60.Fi Electroluminescence
78.20.Jq Electro-optical effects
85.30.Kk Junction diodes

Thermal poling of glass modified by femtosecond laser irradiation

Costantino Corbari, John D. Mills, Olivier Deparis, Bruce G. Klappauf, and Peter G. Kazansky

Appl. Phys. Lett. 81, 1585 (2002); http://dx.doi.org/10.1063/1.1504181 (3 pages) | Cited 9 times

Online Publication Date: 19 August 2002

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Thermal poling of silica glass modified by femtosecond laser irradiation is demonstrated. Increase of second-harmonic generation in the irradiated regions is observed. This enhancement is interpreted in terms of structural modifications in silica glass that make the poling process more efficient. Evidence of a change in the distribution of the electrostatic field frozen in glass during poling is obtained. This technique is used for χ(2) grating fabrication. © 2002 American Institute of Physics.
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42.70.Ce Glasses, quartz
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Enhanced emission with angular confinement from photonic crystals

Stefan Enoch, Boris Gralak, and Gérard Tayeb

Appl. Phys. Lett. 81, 1588 (2002); http://dx.doi.org/10.1063/1.1504166 (3 pages) | Cited 36 times

Online Publication Date: 19 August 2002

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We consider the emission of dipoles embedded in a photonic crystal. We demonstrate that it is possible to obtain an angular confinement of the emission (i.e., a large coherence area) together with an enhancement of the emitted power. A simple geometrical construction gives us a very comprehensive guideline. We illustrate the developed ideas with a structure working at the band edge of an expanded cubic photonic crystal and we take advantage of the large value of the density of states at these wavelengths. Then, it is shown that both directivity and total emitted power can be improved simultaneously without requiring defect modes. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
78.55.-m Photoluminescence, properties and materials

Bright blue to orange photoluminescence emission from high-quality InGaN/GaN multiple-quantum-wells on Si(111) substrates

M. Poschenrieder, F. Schulze, J. Bläsing, A. Dadgar, A. Diez, J. Christen, and A. Krost

Appl. Phys. Lett. 81, 1591 (2002); http://dx.doi.org/10.1063/1.1502909 (3 pages) | Cited 3 times

Online Publication Date: 19 August 2002

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Metalorganic-chemical-vapor-phase-deposition-grown InGaN/GaN multiple-quantum-wells on Si(111) substrates were studied by high-resolution x-ray diffractometry (HRXRD) and photoluminescence (PL). By varying the quantum well deposition parameters, growth time, growth temperature, and In flow rate, systematic changes of the quantum well PL were found. The luminescence peak wavelengths and the corresponding intensities depend monotonically on each of these varied growth parameters. A considerable shift of the PL peak wavelength from blue (442 nm) to orange emission (649 nm) was achieved by decreasing the InGaN deposition temperature from 790 to 720 °C. HRXRD analysis shows changes in structural quality with InGaN growth temperature. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
78.67.De Quantum wells
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Shadowgraphic imaging of the sub-ps laser-induced forward transfer process

D. G. Papazoglou, A. Karaiskou, I. Zergioti, and C. Fotakis

Appl. Phys. Lett. 81, 1594 (2002); http://dx.doi.org/10.1063/1.1497191 (3 pages) | Cited 9 times

Online Publication Date: 19 August 2002

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The subpicosecond laser-induced forward transfer process (LIFT) was investigated by means of time-resolved shadowgraphic imaging. The dynamics of the subpicosecond LIFT process of InOx was investigated for time delays between 0.01 and 10 μs following laser irradiation pulse. Measured values of the velocities of the ejected material were to 400±10 m/s, depending on the laser fluence. The fraction of the material ejected by the subpicosecond LIFT process, which is visible to the shadowgraphic technique was measured to be highly directional with narrow angular divergence (3°). Such direct dynamic transfer of the material opens up application possibilities for the fabrication of high-spatial-resolution microstructures. © 2002 American Institute of Physics.
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79.20.Ds Laser-beam impact phenomena
06.60.Jn High-speed techniques (microsecond to femtosecond)
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Suppressing the transit-time instability in large-area electron-beam diodes

M. Friedman, M. Myers, S. B. Swanekamp, Y. Chan, J. D. Sethian, and S. Obenschain

Appl. Phys. Lett. 81, 1597 (2002); http://dx.doi.org/10.1063/1.1503399 (3 pages) | Cited 8 times

Online Publication Date: 19 August 2002

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Large-area electron-beam diodes are drastically affected by the transit-time instability that introduces a large energy spread to the electrons and generates high-power rf radiation. The instability reduces the energy available for applications such as the excitation of KrF lasers. Simulations and experiments show that replacing the flat cathode with a slotted cathode reduces the growth of the instability. This results in an increase in beam energy transfer efficiency from the Nike diode to the KrF laser from ≈40% to ≈60%. It will be shown that a further increase in efficiency to 76% is possible.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
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Lateral oxidation kinetics of AlxGa1−xAs layer by capacitance technique

N. C. Das, B. Gollsneider, P. Newman, and W. Chang

Appl. Phys. Lett. 81, 1600 (2002); http://dx.doi.org/10.1063/1.1502011 (3 pages) | Cited 2 times

Online Publication Date: 19 August 2002

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Capacitance voltage (C–V) technique is used to determine the kinetics of lateral oxidation of AlxGa1−xAs layer in a circular mesa structure. The oxide layer width determined by the C–V technique agrees with optical measurements. Additionally, the C–V technique has the advantage of determining different types of defects in the oxide, which are important for projecting the reliability of vertical cavity surface emitting laser devices. The wet oxidation between 400 and 435 °C shows negative charges in the oxide.
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81.65.Mq Oxidation
81.05.Ea III-V semiconductors
42.55.Px Semiconductor lasers; laser diodes

Growth mode and matrix effects on the magneto-optical activity of ultrathin films

J. L. Menéndez, G. Armelles, A. Cebollada, C. Quintana, D. Ravelosona, C. Chappert, F. Peiró, and A. Cornet

Appl. Phys. Lett. 81, 1603 (2002); http://dx.doi.org/10.1063/1.1502913 (3 pages) | Cited 5 times

Online Publication Date: 19 August 2002

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The magneto-optical activity of Fe nanoparticulate systems is studied in this work as a function of the matrix that surrounds the particles and the Fe concentration in the effective layer. It is shown that the magneto-optical activity is not linear or proportional to the amount of Fe even at low coverages when the matrix surrounding the particles is an insulator. As a conclusion, it is also demonstrated that the magneto-optical response of a magnetic ultrathin film system strongly depends on its growth mode, with modifications of up to 100% in its magneto-optical activity. © 2002 American Institute of Physics.
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78.20.Ls Magneto-optical effects
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.66.Bz Metals and metallic alloys
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Tt Fine-particle systems; nanocrystalline materials

Electromechanical engraving and writing on bulk metallic glasses

M. F. de Oliveira, W. J. Botta F., C. S. Kiminami, A. Inoue, and A. R. Yavari

Appl. Phys. Lett. 81, 1606 (2002); http://dx.doi.org/10.1063/1.1502008 (3 pages) | Cited 6 times

Online Publication Date: 19 August 2002

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Using the intrinsic materials properties of bulk metallic glasses (BMG), namely electrical resistivities two orders of magnitude higher than good conductors and a Newtonian viscous-flow regime of deformability, a new electromechanical process has been developed for engraving on BMGs. Viscous flow in the supercooled liquid region between the glass transition temperature Tg and the crystallization temperature Tx of the bulk metallic glass allows rapid electromechanical engraving at low applied stresses. Miniaturization of the process is expected to allow submicron engraving in the future. © 2002 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
61.43.Fs Glasses
81.05.Bx Metals, semimetals, and alloys

Phosphorus and arsenic penetration studies through HfSixOy and HfSixOyNz films

M. A. Quevedo-Lopez, M. El-Bouanani, M. J. Kim, B. E. Gnade, R. M. Wallace, M. R. Visokay, A. Li-Fatou, M. J. Bevan, and L. Colombo

Appl. Phys. Lett. 81, 1609 (2002); http://dx.doi.org/10.1063/1.1502910 (3 pages) | Cited 21 times

Online Publication Date: 19 August 2002

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Phosphorus and arsenic penetration studies from P- and As-doped polycrystalline silicon through HfSixOy and HfSixOyNz (18% N) alternate gate dielectric candidates films into Si(100) are presented using a combination of chemical etching and secondary ion mass spectrometry (SIMS). Penetration is observed through HfSixOy after 1050 and 1000 °C rapid thermal annealing for As and P, respectively. In contrast, As or P dopant penetration is at the SIMS limit of detection for HfSixOyNz films. By modeling the P and As depth profiles in the Si substrate, their respective diffusivities in HfSixOy are higher than the corresponding diffusivities in SiO2. The enhanced dopant diffusivity observed in HfSixOy is proposed to be due to grain boundary formation in the dielectric after crystallization from annealing.© 2002 American Institute of Physics.
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61.72.S- Impurities in crystals
77.55.-g Dielectric thin films
61.72.Cc Kinetics of defect formation and annealing
66.30.J- Diffusion of impurities

Mössbauer study of FeCoNbBCu hitperm-type alloys

J. S. Blázquez, A. Conde, and J. M. Grenèche

Appl. Phys. Lett. 81, 1612 (2002); http://dx.doi.org/10.1063/1.1504164 (3 pages) | Cited 13 times

Online Publication Date: 19 August 2002

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FeCoNbBCu alloys have been studied by Mössbauer spectrometry. A high contribution of the interfacial region in the nanocrystalline samples to the hyperfine field distribution is detected. The possible presence of B in the nanocrystalline grains is also discussed. Low values of the hyperfine field with respect to the disordered α-FeCo phase suggest the presence of the ordered α′-FeCo phase. Recrystallization phenomena at the second crystallization stage are confirmed. © 2002 American Institute of Physics.
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76.80.+y Mössbauer effect; other γ-ray spectroscopy
75.50.Kj Amorphous and quasicrystalline magnetic materials
61.46.-w Structure of nanoscale materials
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
71.70.Jp Nuclear states and interactions
64.75.-g Phase equilibria
75.50.Bb Fe and its alloys

Devising a method to measure film adhesion through modeling

C. H. Hsueh

Appl. Phys. Lett. 81, 1615 (2002); http://dx.doi.org/10.1063/1.1504180 (3 pages) | Cited 2 times

Online Publication Date: 19 August 2002

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A method for measuring film adhesion is devised. It consists of a series of patterned film strips with different widths on a substrate, such that the driving force for each strip to debond increases as strip width increases when the system is subjected to residual and/or applied stresses. In this case, only those strips with sufficient driving force debond while the others remain attached to the substrate. Hence, qualitative comparison of the interface debond energy can be obtained by comparing the strip width below which debonding no longer occurs. By calculating the driving force for each strip to debond, the interface debond energy can be quantitatively determined. © 2002 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
68.35.Gy Mechanical properties; surface strains
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