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16 May 2005

Volume 86, Issue 20, Articles (20xxxx)

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Appl. Phys. Lett. 86, 201108 (2005); http://dx.doi.org/10.1063/1.1927712 (3 pages)

P. Vodo, P. V. Parimi, W. T. Lu, and S. Sridhar
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Theory of improved spectral purity in index patterned Fabry-Pérot lasers

S. O’Brien and E. P. O’Reilly

Appl. Phys. Lett. 86, 201101 (2005); http://dx.doi.org/10.1063/1.1919389 (3 pages) | Cited 2 times

Online Publication Date: 9 May 2005

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The spectral purity of a ridge waveguide Fabry-Pérot laser can be improved by patterning the effective refractive index seen by an optical mode propagating in the cavity. Here we present a transmission matrix calculation to first order in the effective index step from which we derive the threshold condition as a function of cavity mode index. This approach enables us to solve the inverse problem relating the index pattern along the cavity to the threshold gain modulation in wavenumber space. Quasiperiodic index patterns are constructed, which lead to improved spectral purity at a predetermined wavelength.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking

Recombination distribution and color tuning of multilayer organic light-emitting diode

Chia-Hsun Chen and Hsin-Fei Meng

Appl. Phys. Lett. 86, 201102 (2005); http://dx.doi.org/10.1063/1.1923759 (3 pages) | Cited 28 times

Online Publication Date: 9 May 2005

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The recombination distribution of an organic light-emitting diode with multiple emissive layers is studied theoretically. Due to the relatively low electron mobility, the recombination concentrates in the layer next to the cathode. As the voltage increases, the recombination extends to the subsequent layers because the electric field strongly enhances the electron mobility. Assume that the layers are arranged in the order of red, green, blue, and electron blocking from the cathode, the emission color can be continuously tuned by the voltage over a wide range. Taking typical material parameters and emission spectra for the layers, we show that Commission Internationale de L’Eclairage coordinate can move from (0.5,0.5) (orange) to (0.3,0.5) (green) to (0.2,0.3) (blue) as the voltage increases from 3 to 13 V. The ratio between the electron and hole mobilities of the green layer and the electron barrier between green and blue layers is found to be crucial for the wide range of color tunability.
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85.60.Jb Light-emitting devices

Midinfrared optical upconverter

D. Ban, H. Luo, H. C. Liu, Z. R. Wasilewski, Y. Paltiel, A. Raizman, and A. Sher

Appl. Phys. Lett. 86, 201103 (2005); http://dx.doi.org/10.1063/1.1921330 (3 pages) | Cited 7 times

Online Publication Date: 9 May 2005

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We have developed a midinfrared optical upconverter by wafer bonding a GaAs/AlGaAs light-emitting diode with an InSb p+nn+ photodetector. The device converts midinfrared radiation in the range of 3–5.45 μm to near-infrared light at 0.84 μm, which can be efficiently detected using a widely available Si charge coupled device. At 77 K, the measured external upconversion efficiency was 0.093 W/W. The optical up-conversion device, in combination with the Si CCD camera, leads to an alternative solution for making low-cost and large-area midinfrared imaging device. Effects of electrical gain and photon recycling inside this integrated device are discussed.
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42.79.Nv Optical frequency converters
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
85.60.Jb Light-emitting devices
42.79.Pw Imaging detectors and sensors
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Coherent coupling of two-dimensional arrays of defect cavities in photonic crystal vertical cavity surface-emitting lasers

James J. Raftery, Aaron J. Danner, Jason C. Lee, and Kent D. Choquette

Appl. Phys. Lett. 86, 201104 (2005); http://dx.doi.org/10.1063/1.1929074 (3 pages) | Cited 18 times

Online Publication Date: 10 May 2005

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An approach for creating two-dimensional arrays of coherently coupled vertically emitting laser cavities is demonstrated. This is achieved by creating a 2×2 array of defect cavities within the top distributed Bragg reflector of a photonic crystal vertical cavity surface-emitting laser. The optical coupling occurs laterally through coupling regions defined between the defect cavities. Modifying the index within the coupling regions, accomplished by varying the hole parameters of the photonic crystal in those regions, leads to out-of-phase coherent coupling observed in the far field. Agreement is found between the simulated and observed out-of-phase far fields.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Tv Photonic crystal lasers and coherent effects
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Polarization conversion and “focusing” of light propagating through a small chiral hole in a metallic screen

A. V. Krasavin, A. S. Schwanecke, N. I. Zheludev, M. Reichelt, T. Stroucken, S. W. Koch, and E. M. Wright

Appl. Phys. Lett. 86, 201105 (2005); http://dx.doi.org/10.1063/1.1925759 (3 pages) | Cited 14 times

Online Publication Date: 10 May 2005

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Propagation of light through a thin flat metallic screen containing a hole of twisted shape is sensitive to whether the incident wave is left or right circularly polarized. The transmitted light accrues a component with handedness opposite to the incident wave. The efficiency of polarization conversion depends on the mutual direction of the hole’s twist and the incident light’s wave polarization handedness and peaks at a wavelength close to the hole overall size. We also observed a strong transmitted field concentration at the center of the chiral hole when the handedness of the chiral hole and the wave’s polarization state are the same.
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78.66.Bz Metals and metallic alloys
42.70.-a Optical materials

Femtosecond laser-drilled capillary integrated into a microfluidic device

Tyson N. Kim, Kyle Campbell, Alex Groisman, David Kleinfeld, and Chris B. Schaffer

Appl. Phys. Lett. 86, 201106 (2005); http://dx.doi.org/10.1063/1.1926423 (3 pages) | Cited 34 times

Online Publication Date: 10 May 2005

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Recent growth in microfluidic technology is, to a large extent, driven by soft lithography, a high-throughput fabrication technique where polymer materials, such as poly(dimethyl) siloxane (PDMS), are molded to form microscopic channel networks. Nevertheless, the channel architectures that can be obtained by molding are limited. We address this limitation by using femtosecond laser micromachining to add unmoldable features to the microfluidic devices. We apply laser ablation to drill microcapillaries, with diameters as small as 0.5 μm and aspect ratios as high as 800:1, in the walls of molded PDMS channels. Finally, we use a laser-drilled microcapillary to trap a polystyrene bead by suction and hold it against a shear flow.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.10.Cm Micromechanical devices and systems
52.38.Mf Laser ablation
42.86.+b Optical workshop techniques
42.70.Jk Polymers and organics
81.20.Wk Machining, milling
81.16.Nd Micro- and nanolithography

Carrier dynamics in self-assembled ErAs nanoislands embedded in GaAs measured by optical-pump terahertz-probe spectroscopy

R. P. Prasankumar, A. Scopatz, D. J. Hilton, A. J. Taylor, R. D. Averitt, J. M. Zide, and A. C. Gossard

Appl. Phys. Lett. 86, 201107 (2005); http://dx.doi.org/10.1063/1.1923174 (3 pages) | Cited 20 times

Online Publication Date: 10 May 2005

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We use optical-pump terahertz (THz)-probe spectroscopy to study carrier dynamics in self-assembled ErAs nanoislands embedded in GaAs and deposited in a superlattice structure. Measurements are performed at several pump fluences on samples with different superlattice periods, enabling a determination of the time-dependent conductivity. Subpicosecond carrier capture times are obtained, indicating the potential of these devices as time-domain THz detectors with performance comparable to low-temperature grown GaAs and superior control of material parameters.
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73.21.Cd Superlattices
73.50.Mx High-frequency effects; plasma effects
78.70.Gq Microwave and radio-frequency interactions
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
81.16.Dn Self-assembly
68.43.Hn Structure of assemblies of adsorbates (two- and three-dimensional clustering)
81.07.-b Nanoscale materials and structures: fabrication and characterization

Focusing by planoconcave lens using negative refraction

P. Vodo, P. V. Parimi, W. T. Lu, and S. Sridhar

Appl. Phys. Lett. 86, 201108 (2005); http://dx.doi.org/10.1063/1.1927712 (3 pages) | Cited 35 times

Online Publication Date: 10 May 2005

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We demonstrate focusing of a plane microwave by a planoconcave lens fabricated from a photonic crystal having a negative refractive index and left-handed electromagnetic properties. An inverse experiment, in which a plane wave is produced from a source placed at the focal point of the lens, is also reported. A frequency-dependent negative refractive index, n(ω)<0 is obtained for the lens from the experimental data which match well with that determined from band structure calculations.
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42.79.Bh Lenses, prisms and mirrors
42.15.Eq Optical system design
42.70.Qs Photonic bandgap materials
84.40.-x Radiowave and microwave (including millimeter wave) technology

Thermal analysis of flip-chip packaged 280 nm nitride-based deep ultraviolet light-emitting diodes

M. Shatalov, A. Chitnis, P. Yadav, Md. F. Hasan, J. Khan, V. Adivarahan, H. P. Maruska, W. H. Sun, and M. Asif Khan

Appl. Phys. Lett. 86, 201109 (2005); http://dx.doi.org/10.1063/1.1927695 (3 pages) | Cited 18 times

Online Publication Date: 10 May 2005

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This letter reports on a low thermal impedance flip-chip packaged deep ultraviolet light-emitting diodes emitting at 280 nm featuring a finned heat sink. For a single 100 μm×100 μm device flip-chip packaged onto an AlN submount and mounted on a TO-66 header with attached finned heat sink, a total junction to ambient thermal impedance as low as 33 °C/W was obtained. Numerical simulations of the heat transfer show that the excessive value of effective thermal impedance is mostly limited by insufficient junction area.
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85.60.Jb Light-emitting devices

Photonic band gaps and localization in the Thue–Morse structures

Xunya Jiang, Yonggang Zhang, Songlin Feng, Kerwyn C. Huang, Yasha Yi, and J. D. Joannopoulos

Appl. Phys. Lett. 86, 201110 (2005); http://dx.doi.org/10.1063/1.1928317 (3 pages) | Cited 22 times

Online Publication Date: 11 May 2005

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Both theoretically and experimentally, we demonstrate that the photonic band gaps in Thue–Morse aperiodic systems can be separated into two flavors, the fractal gaps and the traditional gaps, distinguished by the presence or absence of fractal structure, respectively. The origin of two kind gaps is explained by the different interface correlations. This explanation is confirmed by the gap width behaviors. In addition, the eigenstates near the fractal gaps have a cluster-periodic form, while those near the traditional gaps have the Bloch wavelike form. Our detailed study of these differences is essential for understanding the spectra and light localization in aperiodic systems.
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42.70.Qs Photonic bandgap materials

On-demand single-photon source for 1.3 μm telecom fiber

M. B. Ward, O. Z. Karimov, D. C. Unitt, Z. L. Yuan, P. See, D. G. Gevaux, A. J. Shields, P. Atkinson, and D. A. Ritchie

Appl. Phys. Lett. 86, 201111 (2005); http://dx.doi.org/10.1063/1.1922573 (3 pages) | Cited 45 times

Online Publication Date: 11 May 2005

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We demonstrate an on-demand single-photon source that is compatible with standard telecom optical fiber. Through careful control of the critical strains of InAs/GaAs self-assembled quantum dots, we produce a microcavity sample with a low density of large dots emitting into the fiber-optic transmission band at 1.3 μm. The second-order correlation function of the source reveals a strong suppression in the rate of multiphoton pulses at both 5 K and above 30 K. The source may be useful for fiber-optic-based single-photon applications, such as quantum metrology, quantum communications, and distributed quantum computing.
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42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.72.-g Optical sources and standards
85.30.-z Semiconductor devices

Model for an inversionless two-color laser

C.-R. Lee, Y.-C. Li, F. K. Men, C.-H. Pao, Y.-C. Tsai, and J.-F. Wang

Appl. Phys. Lett. 86, 201112 (2005); http://dx.doi.org/10.1063/1.1931049 (3 pages) | Cited 35 times

Online Publication Date: 11 May 2005

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We propose a model, by taking advantage of quantum interference in a semiconductor quantum-well structure, for two-color lasing without population inversion. In the suggested three-well system, transitions of the lowest three excited states, being coupled to a common continuum by tunneling, to the ground state have been studied. Our results show that the emission spectrum can be arranged in accordance with the initial conditions of the excited states. With the emission peaks located in the vicinities of the absorption zeros resulting from destructive interferences, the nonreciprocal emission-absorption spectra provide a choice of inversionless lasing at two frequencies.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.55.Ah General laser theory

Near-field optical photolithography for high-aspect-ratio patterning using bilayer resist

M. Naya, I. Tsuruma, T. Tani, A. Mukai, S. Sakaguchi, and S. Yasunami

Appl. Phys. Lett. 86, 201113 (2005); http://dx.doi.org/10.1063/1.1931056 (3 pages) | Cited 14 times

Online Publication Date: 11 May 2005

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We attempted to achieve a sufficiently large high-aspect-ratio patterning in near-field optical photolithography employing a bilayer resist process. In this experiment, we formed a resist pattern with a linewidth of 130 nm and a depth of 550 nm. This suggests that a practical method of near-field optical photolithography should become available. We also studied the dependency of an optical pattern on resist film thickness by the three-dimentional finite-difference time-domain method. The calculation results suggest that the resist film thickness affects the distribution of light in the resist.
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85.40.Hp Lithography, masks and pattern transfer
81.16.Rf Micro- and nanoscale pattern formation

Near-infrared electroluminescent devices based on colloidal HgTe quantum dot arrays

É. O’Connor, A. O’Riordan, H. Doyle, S. Moynihan, A. Cuddihy, and G. Redmond

Appl. Phys. Lett. 86, 201114 (2005); http://dx.doi.org/10.1063/1.1928321 (3 pages) | Cited 13 times

Online Publication Date: 12 May 2005

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Crystalline 4.6 nm HgTe quantum dots, stabilized by 1-thioglycerol ligands, were synthesized by wet chemical methods. Room-temperature photoluminescence spectra of the dots, both in solution and as solid arrays, exhibited near-infrared emission. Light-emitting devices were fabricated by deposition of quantum dot layers onto glass∕indium tin oxide (ITO)∕3,4-polyethylene-dioxythiophene-polystyrene sulfonate (PEDOT) substrates followed by top contacting with evaporated aluminum. Room-temperature near-infrared electroluminescence from 1 mm2 ITO∕PEDOT∕HgTe∕Al devices, centered at ∼ 1600 nm, with an external quantum efficiency of 0.02% and brightness of 150 nW/mm2 at 50 mA and 2.5 V was achieved.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
78.55.Et II-VI semiconductors
78.67.Hc Quantum dots

Miniaturizable Si-based electro-optical modulator working at 1.5 μm

Antonella Sciuto, Sebania Libertino, Salvo Coffa, and Giuseppe Coppola

Appl. Phys. Lett. 86, 201115 (2005); http://dx.doi.org/10.1063/1.1928324 (3 pages) | Cited 11 times

Online Publication Date: 12 May 2005

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Optoelectronic devices are considered the innovative element for the next generation of microelectronic integrated circuits. For this purpose, both active and passive devices—extremely miniaturized—must be implemented. We fabricated and electro-optical Si-based light intensity modulator working at 1.5 μm using a bipolar mode field-effect transistor integrated within a Si rib waveguide. The principle of operation is the light absorption by a plasma of free carriers that can be opportunely moved inside or outside of the device optical channel by properly changing the control bias. The devices, only 100 μm long, were fabricated using epitaxial Si wafers and standard clean room processing. The optical characterization at 1.48 μm in static conditions shows a modulation of ∼ 90% while the dynamic electrical characterization provides a switching time of ≈ 10 ns (foreseen modulation frequency of hundreds of MHz). A modulation depth above 25% is observed for modulation frequency up to 300 kHz.
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42.79.Hp Optical processors, correlators, and modulators
42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers
42.86.+b Optical workshop techniques

Terahertz cavity-enhanced attenuated total reflection spectroscopy

Robert Schiwon, Gerhard Schwaab, Erik Bründermann, and Martina Havenith

Appl. Phys. Lett. 86, 201116 (2005); http://dx.doi.org/10.1063/1.1929072 (3 pages) | Cited 3 times

Online Publication Date: 12 May 2005

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We realized cavity-enhanced absorption spectroscopy in the terahertz spectral region by combining multilayer mirrors with an attenuated total reflection technique. Using this technique, we were able to observe an absorbance of biological samples with a minimum detectable concentration as low as 8×10−10 mol/mm2. The absorbance between 75 cm−1 and 115 cm−1 was measured using a monolithic resonator of high-purity silicon. We demonstrate that the sensitivity of the attenuated total reflection design is significantly improved by adding multilayer mirrors for the THz region.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
42.79.Bh Lenses, prisms and mirrors
87.80.-y Biophysical techniques (research methods)
42.15.Eq Optical system design

Nitrogen incorporation effects on gain properties of GaInNAs lasers: Experiment and theory

A. Thränhardt, I. Kuznetsova, C. Schlichenmaier, S. W. Koch, L. Shterengas, G. Belenky, J.-Y. Yeh, L. J. Mawst, N. Tansu, J. Hader, J. V. Moloney, and W. W. Chow

Appl. Phys. Lett. 86, 201117 (2005); http://dx.doi.org/10.1063/1.1929880 (3 pages) | Cited 16 times

Online Publication Date: 12 May 2005

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Gain properties of GaInNAs lasers with different nitrogen concentrations in the quantum wells are investigated experimentally and theoretically. Whereas nitrogen incorporation induces appreciable modifications in the spectral extension and the carrier density dependence of the gain, it is found that the linewidth enhancement factor is reduced by inclusion of nitrogen, but basically unaffected by different nitrogen content due to the balancing between gain and index changes.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Experimental demonstration of a phase-locked laser array using a self-Fourier cavity

Christopher J. Corcoran and Frederic Durville

Appl. Phys. Lett. 86, 201118 (2005); http://dx.doi.org/10.1063/1.1925310 (3 pages) | Cited 46 times

Online Publication Date: 13 May 2005

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A coherent phase-locked laser array has been experimentally demonstrated by combining the outputs of seven individual fiber lasers together in a self-Fourier cavity. By analyzing the interference fringes of the laser output in the far field of the array, a fringe visibility was measured of V = 0.87, indicating a coherence of 0.73. The total output power of this laser array when operated as a coherent ensemble was 0.4 watts.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Wd Fiber lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.30.Kq Fourier optics

Interferometric determination of the anisotropic refractive index dispersion of poly-(p-phenylene-vinylene)

M. Galli, F. Marabelli, and D. Comoretto

Appl. Phys. Lett. 86, 201119 (2005); http://dx.doi.org/10.1063/1.1935035 (3 pages) | Cited 7 times

Online Publication Date: 13 May 2005

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The anisotropic refractive index of highly stretch-oriented free-standing films of poly(p-phenylene-vinylene) has been determined with high accuracy over a broad spectral range by using an interferometric method which directly measures the phase shift of a light-beam passing through the sample. The comparison with transmittance data allows one to evaluate the sample thickness with high precision, avoiding ambiguities in the extraction of the absolute value of the refractive index. The use of polarized light allows evaluation of the strong birefringence of the material.
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78.66.Qn Polymers; organic compounds
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.70.Jk Polymers and organics
42.79.Wc Optical coatings
07.60.Ly Interferometers

Effects of solvent and annealing on the improved performance of solar cells based on poly(3-hexylthiophene): Fullerene

Maher Al-Ibrahim, Oliver Ambacher, Steffi Sensfuss, and Gerhard Gobsch

Appl. Phys. Lett. 86, 201120 (2005); http://dx.doi.org/10.1063/1.1929875 (3 pages) | Cited 73 times

Online Publication Date: 13 May 2005

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Polymer solar cells based on poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) were fabricated using two different solvents. P3HT:PCBM films casted from chlorobenzene solution absorb more red light than the films casted from chloroform solution. After thermal annealing, the films casted from chloroform show higher absorption than the films casted from chlorobenzene. Solar cells made from P3HT:PCBM chlorobenzene solution show no change in the white light power conversion efficiency (2.2%) after annealing. Solar cells processed from P3HT:PCBM chloroform solution show a white light power conversion efficiency of 1.5% without thermal annealing and 3.4% after the thermal annealing. The stated efficiencies are not corrected for the spectral mismatch.
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84.60.Jt Photoelectric conversion
85.60.-q Optoelectronic devices
81.40.Gh Other heat and thermomechanical treatments
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

Microlens arrays with integrated pores as a multipattern photomask

Shu Yang, Chaitanya K. Ullal, Edwin L. Thomas, Gang Chen, and Joanna Aizenberg

Appl. Phys. Lett. 86, 201121 (2005); http://dx.doi.org/10.1063/1.1926405 (3 pages) | Cited 9 times

Online Publication Date: 13 May 2005

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Photolithographic masks are key components in the fabrication process of patterned substrates for various applications. Different patterns generally require different photomasks, whose total cost is high for the multilevel fabrication of three-dimensional microstructures. We developed a photomask that combines two imaging elements—microlens arrays and clear windows—in one structure. Such structures can be produced using multibeam interference lithography. We demonstrate their application as multipattern photomasks; that is, by using the same photomask and simply adjusting (i) the illumination dose, (ii) the distance between the mask and the photoresist film, and (iii) the tone of photoresist, we are able to create a variety of different microscale patterns with controlled sizes, geometries, and symmetries that originate from the lenses, clear windows, or their combination. The experimental results agree well with the light field calculations.
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42.79.Bh Lenses, prisms and mirrors
42.79.Ci Filters, zone plates, and polarizers
42.82.Cr Fabrication techniques; lithography, pattern transfer

Radiation resistance of electro-optic polymer-based modulators

Edward W. Taylor, James E. Nichter, Fazio D. Nash, Franz Haas, Attila A. Szep, Richard J. Michalak, Brian M. Flusche, Paul R. Cook, Tom A. McEwen, Brian F. McKeon, Paul M. Payson, George A. Brost, Andrew R. Pirich, Carlos Castaneda, Boris Tsap, et al.

Appl. Phys. Lett. 86, 201122 (2005); http://dx.doi.org/10.1063/1.1927713 (3 pages) | Cited 8 times

Online Publication Date: 13 May 2005

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Mach–Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation.
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42.79.Hp Optical processors, correlators, and modulators
42.70.Jk Polymers and organics
42.65.-k Nonlinear optics
61.80.Ed γ-ray effects
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Characterization of density profile of laser-produced Sn plasma for 13.5 nm extreme ultraviolet source

Y. Tao, H. Nishimura, S. Fujioka, A. Sunahara, M. Nakai, T. Okuno, N. Ueda, K. Nishihara, N. Miyanaga, and Y. Izawa

Appl. Phys. Lett. 86, 201501 (2005); http://dx.doi.org/10.1063/1.1931825 (3 pages) | Cited 21 times

Online Publication Date: 13 May 2005

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We investigated the electron density profile corresponding to the dominant extreme ultraviolet (EUV) emission from a laser-produced Sn plasma using a combination of a green and an UV interferometer. A comparison between experimental results and a one-dimensional radiation hydrodynamic simulation shows reasonable agreement, and the discrepancy could be attributed to three-dimensional plasma expansion. It was found that, due to opacity effects, most of the EUV light comes from an under-dense plasma region.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.65.Kj Magnetohydrodynamic and fluid equation
52.30.-q Plasma dynamics and flow
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Outdiffusion of La and Al from amorphous LaAlO3 in direct contact with Si (001)

P. Sivasubramani, M. J. Kim, B. E. Gnade, R. M. Wallace, L. F. Edge, D. G. Schlom, H. S. Craft, and J.-P. Maria

Appl. Phys. Lett. 86, 201901 (2005); http://dx.doi.org/10.1063/1.1928316 (3 pages) | Cited 36 times

Online Publication Date: 9 May 2005

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We have evaluated the thermal stability of Al2O3/LaAlO3/Si (001) stacks with atomic force microscopy, x-ray diffraction, transmission electron microscopy, and secondary ion mass spectrometry using a back side polishing approach. Crystallization of the amorphous LaAlO3 film was found to occur for rapid thermal anneals (RTA) above 935 °C for 20 s, in flowing N2. Penetration of Al and La into the underlying Si (001) is clearly observed for RTA at or above 950 °C for 20 s in flowing N2.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
66.30.-h Diffusion in solids
68.37.Ps Atomic force microscopy (AFM)
61.43.Er Other amorphous solids
81.65.Ps Polishing, grinding, surface finishing
61.72.Cc Kinetics of defect formation and annealing
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.37.Lp Transmission electron microscopy (TEM)

Rapid lateral solidification of pure Cu and Au thin films encapsulated in SiO2

J. E. Kline and J. P. Leonard

Appl. Phys. Lett. 86, 201902 (2005); http://dx.doi.org/10.1063/1.1925784 (3 pages) | Cited 2 times

Online Publication Date: 9 May 2005

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Excimer laser melting and lateral resolidification is demonstrated in 200 nm thick Cu and Au elemental metal thin films encapsulated between SiO2 layers. Projection irradiation is used to selectively and completely melt lines 3 to 30 μm wide in the metal film—with rapid lateral solidification originating from the unmelted sidewalls of the molten region—resulting in large columnar grains, extending transversely to the middle of the line. Transmission electron microscopy reveals twinning structures and other defects typical of rapid solidification. Encapsulation and control of the fluence are found to be crucial parameters necessary to prevent film dewetting while molten.
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81.05.Bx Metals, semimetals, and alloys
81.30.Fb Solidification
42.62.-b Laser applications
64.70.D- Solid-liquid transitions
68.37.Lp Transmission electron microscopy (TEM)
61.72.Mm Grain and twin boundaries
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