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17 Nov 1997

Volume 71, Issue 20, pp. 2871-3018

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Maximum output power and maximum operating temperature of quantum well lasers

T. Makino, J. D. Evans, and G. Mak

Appl. Phys. Lett. 71, 2871 (1997); http://dx.doi.org/10.1063/1.120201 (3 pages) | Cited 11 times

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An efficient phenomenological model describing the temperature dependence of the output power of multiquantum well (MQW) lasers is presented. The model can predict all the general features of the experimental results. The effect of series resistance, thermal resistance, cavity length, leakage current, and facet reflectivity on the maximum achievable power are analyzed in a systematic manner. The calculated maximum operating temperature (Tm), defined as the heat sink temperature at which the saturated output power vanishes due to heating, is in reasonable agreement with reported experimental results. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes

Spectroscopy of a ZnCdSe/ZnSSe quantum well diode laser in high magnetic fields

Y.-K. Song, A. V. Nurmikko, T. Schmiedel, C.-C. Chu, J. Han, W.-L. Chen, and R. L. Gunshor

Appl. Phys. Lett. 71, 2874 (1997); http://dx.doi.org/10.1063/1.120202 (3 pages) | Cited 2 times

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We have investigated the characteristics of green–blue II–VI semiconductor diode lasers at room temperature in high magnetic fields. Small spectral shifts, less than 2 meV during the sweep of a field up to 29 T, were measured in ZnCdSe/ZnSSe single quantum well index guided diode devices. This behavior is in contrast with expectations for a noninteracting electron-hole gas in a quantum well system at comparable pair densities ( ∼ 1012 cm−2), implying that the optical gain spectrum shifts diamagnetically. The measured diamagnetic shifts are in close agreement with the low injection electroluminescence and absorption spectra at the n = 1 heavy-hole excitonic transition of the ZnCdSe QW. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.20.Ls Magneto-optical effects
78.45.+h Stimulated emission
78.66.Hf II-VI semiconductors
71.35.-y Excitons and related phenomena

Hydrogen-induced light emission from an organic electroluminescent device

Sumio Okuyama, Yasuaki Ito, Toshiyuki Sugawara, Katsuro Okuyama, Koichi Matsushita, and Junji Kido

Appl. Phys. Lett. 71, 2877 (1997); http://dx.doi.org/10.1063/1.120203 (3 pages)

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An organic electroluminescent device consisting of ITO/aromatic amine/tris(8–quinolinolato)aluminum(Alq3)/Pd was fabricated. The light emission was found to occur when hydrogen gas was present in the ambience and ceased when hydrogen was removed from the Pd electrode. The light emission induced by hydrogen gas was attributed to the work function lowering of the Pd electrode at the Pd–Alq3 interface by adsorption of hydrogen. © 1997 American Institute of Physics.
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78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds
85.60.Jb Light-emitting devices
73.30.+y Surface double layers, Schottky barriers, and work functions
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Large signal dynamics of distributed feedback lasers with spatial modulation of their coupling coefficient and grating pitch

Thierry Fessant

Appl. Phys. Lett. 71, 2880 (1997); http://dx.doi.org/10.1063/1.120204 (3 pages) | Cited 2 times

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A multimode time domain model is used to study the large signal dynamics of complex distributed feedback lasers with nonuniform grating pitch and coupling coefficient. Lasers with longitudinal variation of their grating pitch Λ (corrugation-pitch-modulated lasers) can exhibit poor steady-state side mode suppression ratios. Numerical simulations show that an adequate profile of the coupling coefficient κ (stronger coupling at the center of the cavity) can help to achieve improved steady-state single mode operation with respect to conventional Bragg-detuned cavities (uniform coupling coefficient). However, it is found that in such lasers (z-dependent κ), side modes are liable to be excited during the turn-on transient interval. A careful study of the turn-on transient is needed to determine the maximum (keeping dynamic single mode regime) bias current. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes

Efficient white light-emitting diodes realized with new processable blends of conjugated polymers

S. Tasch, E. J. W. List, O. Ekström, W. Graupner, G. Leising, P. Schlichting, U. Rohr, Y. Geerts, U. Scherf, and K. Müllen

Appl. Phys. Lett. 71, 2883 (1997); http://dx.doi.org/10.1063/1.120205 (3 pages) | Cited 183 times

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An alternative method for producing efficient white light-emitting polymer diodes based on a blend of two polymers is reported. The white light emission is composed of a broad blue emission of laddertype (polyparaphenylene) (m-LPPP) and a red-orange emission of a new polymer, poly(perylene-co-diethynylbenzene) (PPDB). The red-orange electroluminescence emission is promoted by an excitation energy and charge transfer from m-LPPP to the PPDB. A concentration of 0.05% PPDB in the polymer blend is required in order to obtain white light emission. By inserting an insulating material in the blend, so that a maximum external quantum efficiency of 1.2% is obtained. © 1997 American Institute of Physics.
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42.70.Jk Polymers and organics
85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence

High-efficiency and high-resolution fiber-optic probes for near field imaging and spectroscopy

M. N. Islam, X. K. Zhao, A. A. Said, S. S. Mickel, and C. F. Vail

Appl. Phys. Lett. 71, 2886 (1997); http://dx.doi.org/10.1063/1.120206 (3 pages) | Cited 29 times

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We demonstrate that fiber-optic probes with an intermediate section followed by a rapidly tapering tip lead to transmission efficiency enhancement of better than four orders-of-magnitude at 60 nm tip diameter and more than five orders-of-magnitude at smaller than 40 nm tip diameter over typical taffy-pulled fiber probes. Our highest resolution probes have a tip diameter of 30 nm with a transmission efficiency of 0.02%, and as an example we image tobacco mosaic virus with a resolution better than 35 nm. The probes are made in a two-step process involving pulling and then etching that permits both high efficiency and control of the mechanical resonance properties. The efficiency is enhanced by reducing the distance that the electromagnetic mode travels in the cut-off mode of the fiber probe. The higher resolution is achieved because sharper tips can be made through the etching process. © 1997 American Institute of Physics.
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07.60.Vg Fiber-optic instruments
42.81.Wg Other fiber-optical devices
07.79.Fc Near-field scanning optical microscopes
87.80.-y Biophysical techniques (research methods)

Novel application of a perturbed photonic crystal: High-quality filter

Xin-Ya Lei, Hua Li, Feng Ding, Weiyi Zhang, and Nai-Ben Ming

Appl. Phys. Lett. 71, 2889 (1997); http://dx.doi.org/10.1063/1.120207 (3 pages) | Cited 19 times

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The transmission of light waves through a perturbed photonic crystal has been investigated. The perturbed photonic crystal was constructed by randomly repeated stacking of a number of identical unit cells. Although most of the light waves are localized by the randomness, there still exist light waves with special wavelengths which are in extended states. This produces a high-quality resonant tunneling with a very narrow transmission coefficient peak. © 1997 American Institute of Physics.
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42.50.-p Quantum optics
42.70.Qs Photonic bandgap materials
42.79.Ci Filters, zone plates, and polarizers

Mid-infrared electroluminescence in GaAs/AlGaAs structures

G. Strasser, P. Kruck, M. Helm, J. N. Heyman, L. Hvozdara, and E. Gornik

Appl. Phys. Lett. 71, 2892 (1997); http://dx.doi.org/10.1063/1.119329 (3 pages) | Cited 12 times

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Design, growth, and operation of an unipolar light emitting diode based on the material system GaAs/AlGaAs is reported. We present mid-infrared transmission, photocurrent, and electroluminescence measurements on a quantum cascade structure with intersubband transition energies greater than the optical phonon energy. Electroluminescence powers up to a few nanowatts at 6.9 μm have been measured. © 1997 American Institute of Physics.
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85.60.Jb Light-emitting devices
81.05.Ea III-V semiconductors
78.60.Fi Electroluminescence
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
72.40.+w Photoconduction and photovoltaic effects

Highly-sensitive passive integrated optical spiral-shaped waveguide refractometer

G. J. Veldhuis and P. V. Lambeck

Appl. Phys. Lett. 71, 2895 (1997); http://dx.doi.org/10.1063/1.120208 (3 pages) | Cited 12 times

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A passive integrated optical waveguide refractometer based on bendloss changes in a spiral-shaped channel waveguide is proposed and fabricated in Si3N4/SiO2 technology. The experimentally determined performance and the theoretical predictions, based on a simple model for so-called “whispering gallery modes,” agree very well. The minimum detectable refractive index change was measured to be Δn = 1.3×10−5. © 1997 American Institute of Physics.
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07.60.Hv Refractometers and reflectometers
85.60.-q Optoelectronic devices
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.65.Wi Nonlinear waveguides
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Optical properties of GaN/AlGaN multiple quantum well microdisks

R. A. Mair, K. C. Zeng, J. Y. Lin, H. X. Jiang, B. Zhang, L. Dai, H. Tang, A. Botchkarev, W. Kim, and H. Morkoç

Appl. Phys. Lett. 71, 2898 (1997); http://dx.doi.org/10.1063/1.120209 (3 pages) | Cited 19 times

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An array of microdisks with a diameter of about 9 μm and spacing of 50 μm has been fabricated by dry etching from a 50 Å/50 Å GaN/AlxGa1-xN (x ∼ 0.07) multiple quantum well (MQW) structure grown by reactive molecular beam epitaxy. Optical properties of these microdisks have been studied by picosecond time-resolved photoluminescence (PL) spectroscopy. Photoluminescence emission spectra and decay dynamics were measured at various temperatures and pump intensities. With respect to the original MQWs, we observe strong enhancement of the transition intensity and lifetime for both the intrinsic and barrier transitions. The intrinsic transition is excitonic at low temperatures and exhibits an approximate tenfold increase in both lifetime and PL intensity upon formation of the microdisks. This implies a significant enhancement of quantum efficiency in microdisks and a bright future for III-nitride microcavity lasers. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
81.65.Cf Surface cleaning, etching, patterning
78.47.-p Spectroscopy of solid state dynamics
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Picosecond responses of low-dosage arsenic-ion-implanted GaAs photoconductors

Gong-Ru Lin and Ci-Ling Pan

Appl. Phys. Lett. 71, 2901 (1997); http://dx.doi.org/10.1063/1.120210 (3 pages) | Cited 7 times

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Ultrafast optoelectronic characteristics of GaAs implanted with 200 keV arsenic ions at dosage as low as 1013 ions/cm2 are reported. Ultrashort photoexcited carrier lifetimes of 0.23±0.02, 0.87±0.02, and 3±0.2 ps were determined for as-implanted, rapid thermal annealing (RTA) (600 °C for 30 s) and furnace-annealed (600 °C for 30 min) arsenic-ion-implanted GaAs or GaAs:As+, respectively. The switching response of photoconductive switches (PCSs) fabricated on the latter two materials were ∼ 3 and 8 ps, respectively. The leakage current of the PCS fabricated on furnace-annealed sample was as low as 30 nA. The breakdown fields exceeded 150 (instrument-limited) and 90 kV/cm for furnace- and RTA-annealed samples, respectively. The optical responsivity of low-dosage arsenic-implanted GaAs photoconductive switch can be as high as 0.01 A/W. This also compared favorably with the same device made on state-of-the-art photoconductor such as molecular-beam epitaxy grown GaAs at low temperatures. © 1997 American Institute of Physics.
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85.60.Bt Optoelectronic device characterization, design, and modeling
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
85.40.Ry Impurity doping, diffusion and ion implantation technology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
72.40.+w Photoconduction and photovoltaic effects
61.72.uj III-V and II-VI semiconductors
61.80.Jh Ion radiation effects

Photoluminescence of Nd-doped LiNbO3 films prepared by pulsed laser deposition

J. E. Alfonso, M. J. Martín, and C. Zaldo

Appl. Phys. Lett. 71, 2904 (1997); http://dx.doi.org/10.1063/1.120211 (3 pages) | Cited 6 times

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Nd-doped LiNbO3 films have been prepared on (012) sapphire substrates by pulsed laser deposition. LiNbO3 phase is formed using Li rich targets, a 1.5×10−2 mbar oxygen pressure atmosphere, and heating the substrate to 520 °C. The crystallinity of 1-μm-thick films has been enhanced by postdeposition thermal treatments at 600 °C. The [Nd]/[Nb] concentration ratio in the film is equal to its value in the target; however, a limit for the Nd incorporation to the LiNbO3 phase has been found due to the preferential nucleation of Li deficient phases for [Nd]/[Nb]>0.1. The Nd photoluminescence of the films have been studied at 77 K exciting the 4F3/2 multiplet. The photoluminescence of congruent LiNbO3 single crystals is well reproduced in films prepared from targets with a [Li]/[Nb] = 1.6 composition. Films prepared from targets with a [Li]/[Nb] = 3 composition, additionally show an emission, with a main maximum at 1064 nm, the splitting of the 4F3/2 multiplet being 80 cm−1. The possible origin of the latter photoluminescence is discussed. © 1997 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
81.15.Fg Pulsed laser ablation deposition
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
78.66.-w Optical properties of specific thin films

Control of liquid crystal alignment by polyimide surface modification using atomic force microscopy

A. J. Pidduck, S. D. Haslam, G. P. Bryan-Brown, R. Bannister, and I. D. Kitely

Appl. Phys. Lett. 71, 2907 (1997); http://dx.doi.org/10.1063/1.120212 (3 pages) | Cited 37 times

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Atomic force microscopy (AFM) has been used to modify a polyimide surface to give controlled liquid crystal (LC) alignment, and to examine the modification produced. Strong LC azimuthal anchoring was observed typically for normal forces >300 nN and line densities >5 μm−1, and optically diffracting LC elements were fabricated by repeatedly overpatterning the same area along different directions. Atomic force microscopy images showed little sign of topographic modification such as grooving, whereas lateral force images showed locally increased friction. Estimated contact pressures, 0.08–0.3 GPa, suggest shear-yielding occurs within a surface layer, causing polymer chain alignment. The AFM micromechanical interaction is compared with that occurring during the conventional cloth-rubbing LC alignment process.
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61.30.-v Liquid crystals
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
68.35.B- Structure of clean surfaces (and surface reconstruction)

The crucial role of doping for high repetition rate monolithic mode locking of multiple quantum well GaAs/AlGaAs lasers

S. D. McDougall, B. Vögele, C. R. Stanley, and C. N. Ironside

Appl. Phys. Lett. 71, 2910 (1997); http://dx.doi.org/10.1063/1.120213 (3 pages) | Cited 1 time

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Monolithic colliding pulse mode locking of a molecular beam epitaxy (MBE) grown GaAs/AlGaAs quantum well laser has been achieved through back doping of the active region to simulate the residual doping present in metal organic vapor phase epitaxy grown mode-locked laser wafers. Frequency domain measurements are presented which show multiple colliding pulse mode-locked operation of an MBE grown device at 186 and 372 GHz. Devices with no intentional doping in the active layer showed no evidence of mode-locked operation. Band-edge absorption spectra are also presented which indicate the effect doping has in broadening the excitonic linewidth in the saturable absorber. © 1997 American Institute of Physics.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Px Semiconductor lasers; laser diodes
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency

Ellipsometric monitoring of an oriented diamond nucleation process in bias-enhanced chemical vapor deposition

Yasuaki Hayashi, Xi Li, and Shigehiro Nishino

Appl. Phys. Lett. 71, 2913 (1997); http://dx.doi.org/10.1063/1.120214 (3 pages) | Cited 1 time

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The process of bias-enhanced nucleation of diamond has been monitored and analyzed by ellipsometry. The time evolution of optically equivalent thickness has been obtained and it has been confirmed with the help of x-ray photoelectron spectroscopy that four stages exist: they are carbonization, incubation, nuclei growth, and film growth. It has been considered, during the incubation stage, that carbonization and etching proceed simultaneously and that high density and oriented diamond nuclei are generated by the accelerated elimination of weak C–C bonds and the faster formation of sp3 C–C bonds in a substrate. © 1997 American Institute of Physics.
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81.05.Cy Elemental semiconductors
81.05.ub Fullerenes and related materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
79.60.Bm Clean metal, semiconductor, and insulator surfaces
78.66.Db Elemental semiconductors and insulators

Removal of thin layer for trace element analysis of solid surface in subnanometer scale using laser-ablation atomic fluorescence spectroscopy

Yuji Oki, Kenji Matsunaga, Takumi Nomura, and Mitsuo Maeda

Appl. Phys. Lett. 71, 2916 (1997); http://dx.doi.org/10.1063/1.120215 (3 pages) | Cited 3 times

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Laser-ablation atomic fluorescence (LAAF) spectroscopy has extremely high sensitivity in the analysis of trace elements. Using the ArF laser-ablation technique at a wavelength of 193 nm, removal of thin surface layer of the order of 1.1 nm/shot for the first 50 shots and 0.4 nm/shot after that is demonstrated for a solid glass sample. A constant fluorescence signal from Na atoms is obtained for each shot. There is a possibility of determining the depth distribution of an element with subnanometer resolution by applying LAAF spectroscopy. © 1997 American Institute of Physics.
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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
68.35.B- Structure of clean surfaces (and surface reconstruction)
79.20.Ds Laser-beam impact phenomena
81.65.-b Surface treatments

Photoconductivity and charge transporting properties of metal-containing poly(p-phenylenevinylene)s

Wai Kin Chan, Xiong Gong, and Wai Yue Ng

Appl. Phys. Lett. 71, 2919 (1997); http://dx.doi.org/10.1063/1.120548 (3 pages) | Cited 15 times

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A novel type of poly(p-phenylenevinylene)s which contain (bis(2,2′:6′,2′′-terpyridine) ruthenium (II) complexes has been developed. The absorption of the polymers at 500 nm was strongly enhanced by the metal complexes due to the presence of the metal–ligand charge transfer transition. The charge transportation is dispersive with hole carrier mobilities and activation energy of ∼ 7×10−5 cm2 V−1 s−1 and 0.20 eV, respectively, depending on the concentration of the metal complex. A log μ vs E1/2 plot shows that hole mobilities decrease with increasing field, which suggests the presence of off-diagonal disorder in the hopping sites. © 1997 American Institute of Physics.
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72.40.+w Photoconduction and photovoltaic effects
72.80.Le Polymers; organic compounds (including organic semiconductors)
72.20.Fr Low-field transport and mobility; piezoresistance

Erbium-doped phosphate glass waveguide on silicon with 4.1 dB/cm gain at 1.535 μm

Y. C. Yan, A. J. Faber, H. de Waal, P. G. Kik, and A. Polman

Appl. Phys. Lett. 71, 2922 (1997); http://dx.doi.org/10.1063/1.120216 (3 pages) | Cited 97 times

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Erbium-doped multicomponent phosphate glass waveguides were deposited by rf sputtering techniques. The Er concentration was 5.3×1020 cm−3. By pumping the waveguide at 980 nm with a power of ∼ 21 mW, a net optical gain of 4.1 dB at 1.535 μm was achieved. This high gain per unit length at low pump power could be achieved because the Er–Er cooperative upconversion interactions in this heavily Er-doped phosphate glass are very weak [the upconversion coefficient is (2.0±0.5)×10−18 cm3/s], presumably due to the homogeneous distribution of Er in the glass and due to the high optical mode confinement in the waveguide which leads to high pump power density at low pump power. © 1997 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.79.Gn Optical waveguides and couplers

Investigations of double capillary discharge scheme for production of wave guide in plasma

D. Kaganovich, P. V. Sasorov, Y. Ehrlich, C. Cohen, and A. Zigler

Appl. Phys. Lett. 71, 2925 (1997); http://dx.doi.org/10.1063/1.120217 (3 pages) | Cited 20 times

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Double capillary scheme is proposed for high performance electrical discharge in a capillary. This scheme allows more than 103 shots without significant destruction. It is shown that a thin main capillary can be filled with the plasma formed in a trigger capillary discharge so that the discharge in the main capillary can be excited and a hollow distribution of electron density can be obtained with concentration of up to a few 1019 cm−3. Main properties of this scheme are reported. © 1997 American Institute of Physics.
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52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.80.Sm Magnetoactive discharges (e.g., Penning discharges)
84.40.Az Waveguides, transmission lines, striplines
52.25.-b Plasma properties

How tunneling currents reduce plasma-induced charging

Gyeong S. Hwang and Konstantinos P. Giapis

Appl. Phys. Lett. 71, 2928 (1997); http://dx.doi.org/10.1063/1.120218 (3 pages) | Cited 7 times

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As semiconductor manufacturing moves towards smaller logic devices and thinner gate oxides, there is serious concern that pattern-dependent charging during plasma etching will impede progress by distorting etch profiles and by causing oxide breakdown. Simulations of the final overetch predict that the use of ultrathin oxides ( ⩽ 5 nm), combined with a low substrate potential, will actually eliminate notching by enabling electron tunneling from the substrate to decrease surface charging potentials at the bottom of high aspect ratio trenches. Comparison with published experimental results validates the simulations. © 1997 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
73.40.Gk Tunneling

Microstructure of GaN layers grown on (001) GaAs by plasma assisted molecular-beam epitaxy

Sergei Ruvimov, Zuzanna Liliental-Weber, Jack Washburn, Timothy J. Drummond, Michael Hafich, and Stephen R. Lee

Appl. Phys. Lett. 71, 2931 (1997); http://dx.doi.org/10.1063/1.120219 (3 pages) | Cited 11 times

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High resolution electron microscopy has been applied to characterize the structure of β-GaN epilayers grown on (001) GaAs substrates by plasma-assisted molecular-beam epitaxy. An rf plasma source was used to promote chemically active nitrogen. An exposure of the layer surface to the As flux during the growth of the first few monolayers was shown to result in remarkably flat GaN–GaAs interface. The best quality GaN layers were achieved by near-stoichiometric nucleation with optimal Ga-to-N ratio. Deviation from these nucleation conditions leads to interface roughening and formation of the wurtzite phase within the GaN layer. All the layers contained a high density of stacking faults near the interface which sharply decreases toward the surface. Stacking faults were anisotropically distributed within the GaN layer probably due to different properties of α compared to β dislocations in cubic GaN. The majority of stacking faults intersect the interface along lines parallel to the major flat of the GaAs wafer. The stacking faults are often associated with atomic steps at the GaN–GaAs interface. © 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.Ct Interface structure and roughness
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Nn Stacking faults and other planar or extended defects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Nanostructure array fabrication with a size-controllable natural lithography

Chiseki Haginoya, Masayoshi Ishibashi, and Kazuyuki Koike

Appl. Phys. Lett. 71, 2934 (1997); http://dx.doi.org/10.1063/1.120220 (3 pages) | Cited 88 times

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A simple technique for size-controllable nanostructure array formation has been developed, using self-assembled polystyrene beads whose diameters can be arbitrarily reduced by reactive ion etching. We have produced a hole array of 83 and 157 nm diameter with 200 nm pitch on Si substrate. This technique can find potential applications in many areas of science and technology. © 1997 American Institute of Physics.
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85.40.Hp Lithography, masks and pattern transfer
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
81.65.Cf Surface cleaning, etching, patterning
81.05.Cy Elemental semiconductors

Molecular scale alignment strategies: An investigation of Ag adsorption on patterned fullerene layers

A. W. Dunn, B. N. Cotier, A. Nogaret, P. Moriarty, P. H. Beton, and S. P. Beaumont

Appl. Phys. Lett. 71, 2937 (1997); http://dx.doi.org/10.1063/1.120221 (3 pages) | Cited 9 times

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We have developed a procedure for atomic scale alignment with respect to macroscopic objects. Metallic and etched registration marks on clean reconstructed Si surfaces are used to guide the tip of a scanning tunnelling microscope. The metallic marks are formed from Ta and can withstand thermal cycling up to 1500 K. These procedures have been used to investigate the interaction of Ag with a patterned fullerene multilayer deposited on Si(111)-7×7. © 1997 American Institute of Physics.
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61.48.-c Structure of fullerenes and related hollow and planar molecular structures
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
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
81.65.-b Surface treatments

Scanning tunneling microscopy of ordered coated cluster layers on graphite

P. J. Durston, J. Schmidt, R. E. Palmer, and J. P. Wilcoxon

Appl. Phys. Lett. 71, 2940 (1997); http://dx.doi.org/10.1063/1.120222 (3 pages) | Cited 25 times

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Surfactant stabilized gold clusters have been deposited on graphite and studied with scanning tunneling microscopy in vacuum. Cluster layers with a superlattice constant of ≈ 31 Å were found, extending over several micrometers. The clusters form a hexagonal lattice which is ordered over distances of about 100 Å. At low sample biases (<0.75 V) the clusters are not imaged, consistent with a Coulomb blockade effect. © 1997 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
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
73.23.Hk Coulomb blockade; single-electron tunneling

Formation of a crystalline phase in amorphous hydrogenated carbon-germanium films by electron beam irradiation

J. Tyczkowski, B. Pietrzyk, R. Mazurczyk, K. Polański, J. Balcerski, and M. Delamar

Appl. Phys. Lett. 71, 2943 (1997); http://dx.doi.org/10.1063/1.120223 (3 pages) | Cited 5 times

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The influence of electron beam irradiation on morphology of plasma deposited amorphous hydrogenated carbon-germanium films produced from tetramethylgermanium in a three-electrode af reactor has been studied. It has been found that the insulating films are insensitive to this treatment, whereas a crystalline phase occurs in the semiconducting films. Although the molar content of germanium in these films amounts only to about 0.2, the crystalline phase is composed of pure germanium nanocrystals which contain about 70% of the whole amount of germanium existing in the films. The nanocrystals are agglomerated in globules of 50–500 nm in diameter. © 1997 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.80.Fe Electron and positron radiation effects
64.70.K- Solid-solid transitions
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