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20 Aug 2001

Volume 79, Issue 8, pp. 1073-1217

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Stabilization of the repetition rate of passively Q-switched diode-pumped solid-state lasers

Ngoc Diep Lai, Marc Brunel, Fabien Bretenaker, and Albert Le Floch

Appl. Phys. Lett. 79, 1073 (2001); http://dx.doi.org/10.1063/1.1396320 (3 pages) | Cited 13 times

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We present a simple technique to stabilize the period of the pulses emitted by passively Q-switched lasers. By slightly modulating the pump diode power, the repetition rate of a Nd3+:YAG laser passively Q switched by Cr4+:YAG is experimentally shown to reach a time stability of 10−6 over 106 pulses. Simulations using a rate-equation model are in close agreement with the experiments. © 2001 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Px Semiconductor lasers; laser diodes

Bend loss in surface plasmon polariton band-gap structures

Sergey I. Bozhevolnyi, Valentyn S. Volkov, Kristjan Leosson, and Alexandra Boltasseva

Appl. Phys. Lett. 79, 1076 (2001); http://dx.doi.org/10.1063/1.1389507 (3 pages) | Cited 41 times

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Using near-field optical microscopy, we investigate propagation of surface plasmon polaritons (SPPs) excited in the wavelength range of 720–830 nm at a corrugated gold-film surface with areas of 200-nm-wide and 45-nm-high scatterers arranged in a 410-nm-period triangular lattice containing line defects with double bends. We find that, for ∼2-μm-wide line defects and the wavelength of ∼740 nm, the double bend losses for bend angles of 15° and 30° are below 2 and 10 dB, respectively. Our data indicate that the bend loss increases approximately quadratically with the bend angle. We also demonstrate splitting and combining of two SPP line-defect modes in a 20-μm-long Y junction. © 2001 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Light-induced self-written three-dimensional optical waveguide

Manabu Kagami, Tatsuya Yamashita, and Hiroshi Ito

Appl. Phys. Lett. 79, 1079 (2001); http://dx.doi.org/10.1063/1.1389516 (3 pages) | Cited 54 times

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Three-dimensional (3D) optical waveguides were fabricated in a photopolymerizing resin mixture solution by using a multimode optical fiber, without any moving parts. The core portion has formed by the selective photopolymerization of a higher refractive index monomer by Ar+ laser irradiation through the optical fiber. A continuous, straight waveguide was grown by the self-trapping of a guided laser beam. We demonstrated automatic 3D optical circuit formation that enables regrowth after passing through thick transparent glass plates. This growth mechanism also enables automation of the optical interconnection and packaging process, and could potentially contribute to future expansion of optical fiber communications networks. © 2001 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.81.Bm Fabrication, cladding, and splicing
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
82.35.-x Polymers: properties; reactions; polymerization
82.50.-m Photochemistry
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.82.Ds Interconnects, including holographic interconnects
42.82.Et Waveguides, couplers, and arrays
42.70.Jk Polymers and organics

Intense and stable blue-light emission of Pb(ZrxTi1−x)O3

Chang Q Sun, Da Jin, Ji Zhou, S. Li, B. K. Tay, S. P. Lau, X. W. Sun, H. T. Huang, and P. Hing

Appl. Phys. Lett. 79, 1082 (2001); http://dx.doi.org/10.1063/1.1394946 (3 pages) | Cited 8 times

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A single band of photoluminescence (PL) has been detected at room temperature from the Pb(ZrxTi1−x)O3 (x = 0–1.0) surface. The intense and stable PL band covers 475±50 nm (or 2.67±0.25 eV) wavelengths and the corresponding photoexcitation (PE) band is in the range of 305±45 nm. It is found that changing the x value causes a negligible shift of the PL and PE peaks, and the light emission is subject to the Pb presence. The minimal lifetime of the excited photons was found to be 0.03 ms at x = 0.5 and the maximum lifetime of 0.60 ms can be achieved by either decreasing or increasing the x values. © 2001 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
61.66.Bi Elemental solids
61.66.Dk Alloys

Influence of localized nitrogen states on material gain in InGaAsN/GaAs quantum-well lasers

J. C. L. Yong, J. M. Rorison, and I. H. White

Appl. Phys. Lett. 79, 1085 (2001); http://dx.doi.org/10.1063/1.1390482 (3 pages) | Cited 8 times

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The effect of the nature of nitrogen incorporation in the InGaAsN/GaAs quantum well system on gain is investigated. The nitrogen is considered to be either fully incorporated within the lattice or to be incorporated as a localized acceptor. In the latter case this results in conduction-band anticrossing, causing nonparabolicity. The resulting gains from the two extreme limits are compared and found to be similar. This shows that the nature of the nitrogen incorporation is not a key issue in the performance of InGaAsN/GaAs quantum well lasers for 1.3 μm applications. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
73.21.Fg Quantum wells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
71.55.Eq III-V semiconductors

Wavelength tunable diffractive transmission lens for hard x rays

C. David, B. Nöhammer, and E. Ziegler

Appl. Phys. Lett. 79, 1088 (2001); http://dx.doi.org/10.1063/1.1379364 (3 pages) | Cited 17 times

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We report on the fabrication and testing of linear transmission Fresnel zone plates for hard x rays. The diffractive elements are generated by electron beam lithography and chemical wet etching of 〈110〉 oriented silicon substrates. By tilting the cylindrical lenses with respect to the x-ray beam, the effective path through the phase shifting zones can be varied. This makes it possible to optimize the diffraction efficiency over a wide range of photon energies, and to obtain effective aspect ratios not accessible with untilted optics. The diffraction efficiency of such a lens was measured as a function of the tilt angles for various energies between 8 and 29 keV. Values close to the theoretical limit were obtained for all energies. Because of the coherence preserving properties of diffractive optics, the method opens up opportunities for experiments using coherent hard x rays. © 2001 American Institute of Physics.
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07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
41.50.+h X-ray beams and x-ray optics
61.05.cp X-ray diffraction
07.85.-m X- and γ-ray instruments

Observation of an anomalously large blueshift of the photoluminescence peak and evidence of band-gap renormalization in InP/InAs/InP quantum wires

Xiaodong Mu, Ioulia B. Zotova, Yujie J. Ding, Haeyeon Yang, and Gregory J. Salamo

Appl. Phys. Lett. 79, 1091 (2001); http://dx.doi.org/10.1063/1.1390483 (3 pages) | Cited 7 times

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We have investigated polarization-dependent photoluminescence in InP/InAs/InP quantum wires directly formed on the top of InP substrates. With excitation laser intensity we have observed an anomalously large blueshift of the photoluminescence peak using a cw laser with extremely low intensities. We have also observed evidence of band-gap renormalization. In addition, we have measured two-photon luminescence spectra and confirmed their dependence on photoluminescence polarization. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.67.Lt Quantum wires
73.21.Hb Quantum wires
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Origin of improved luminescence efficiency after annealing of Ga(In)NAs materials grown by molecular-beam epitaxy

Wei Li, Markus Pessa, Tommy Ahlgren, and James Decker

Appl. Phys. Lett. 79, 1094 (2001); http://dx.doi.org/10.1063/1.1396316 (3 pages) | Cited 73 times

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Positron-annihilation measurements and nuclear reaction analysis [utilizing the 14N(d,p)15N and 14N(d,He)12C reactions] in conjunction with Rutherford backscattering spectrometry in the channeling geometry were used to study the defects in as-grown Ga(In)NAs materials grown by molecular beam epitaxy using a radio-frequency plasma nitrogen source. Our data unambiguously show the existence of vacancy-type defects, which we attribute to Ga vacancies, and nitrogen interstitials in the as-grown nitride–arsenide epilayers. These point defects, we believe, are responsible for the low luminescence efficiency of as-grown Ga(In)NAs materials and the enhanced diffusion process during annealing. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

Quantum beats of free and bound excitons in GaN

K. Kyhm, R. A. Taylor, J. F. Ryan, T. Aoki, M. Kuwata-Gonokami, B. Beaumont, and P. Gibart

Appl. Phys. Lett. 79, 1097 (2001); http://dx.doi.org/10.1063/1.1391411 (3 pages) | Cited 2 times

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We present spectrally resolved and time-integrated four-wave mixing measurements at coherent dynamics of bound excitons in a high-quality GaN epilayer. Coherent excitation, with co-circular polarized light, of the neutral donor-bound excitons (D 0X) and A excitons (XA) results in quantum beats, corresponding to the energy splitting between D 0X and XA. The temperature-dependent dephasing rate is used to deduce the strength of the D 0X-acoustic–phonon interaction via the homogeneous linewidth. © 2001 American Institute of Physics.
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71.35.Gg Exciton-mediated interactions
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
63.20.kk Phonon interactions with other quasiparticles
78.47.-p Spectroscopy of solid state dynamics
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Current-modulated electroluminescence spectroscopy and its application to InGaN single-quantum-well blue and green light-emitting diodes

Takashi Azuhata, Takefumi Homma, Yoshikazu Ishikawa, Shigefusa F. Chichibu, Takayuki Sota, and Takashi Mukai

Appl. Phys. Lett. 79, 1100 (2001); http://dx.doi.org/10.1063/1.1396312 (3 pages) | Cited 1 time

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Current-modulated electroluminescence spectroscopy was developed to investigate the mechanism of the current-induced spectral blueshift in InGaN single-quantum-well blue and green light-emitting diodes. The evidence was obtained that tail states exist in InGaN active layers, and also the blueshift was found to be dominated by the tail-state filling effect. © 2001 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices

Effects of boron-interstitial silicon clusters on interstitial supersaturation during postimplantation annealing

S. Solmi, L. Mancini, S. Milita, M. Servidori, G. Mannino, and M. Bersani

Appl. Phys. Lett. 79, 1103 (2001); http://dx.doi.org/10.1063/1.1396310 (3 pages) | Cited 15 times

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Boron marker-layer structures have been used to investigate the effects of B doping on the evolution of the implantation damage and of the associated transient enhanced diffusion. The samples were damaged by Si implants at different doses in the range 2×1013–1×1014 cm−2 and annealed at 740 °C for times between 2 s and 4 h. The values of interstitial supersaturation, from the beginning of the annealing up to the complete damage recovery, have been determined for the different Si doses for a given B doping level. Damage removal has been followed by double crystal x-ray diffraction. Our results confirm that the formation of boron-interstitial silicon clusters traps a relevant fraction of the interstitials produced by the implantation. This trapping action gives rise to a strong reduction of the interstitial supersaturation, prevents the interstitial clusters from being transformed in {113} defects and modifies the time evolution of the transient enhanced diffusion. X-ray analyses indicate also that the size of the boron-interstitial silicon clusters remains below 2 nm. © 2001 American Institute of Physics.
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81.05.Cy Elemental semiconductors
66.30.J- Diffusion of impurities
61.72.J- Point defects and defect clusters
61.72.uf Ge and Si
61.72.Cc Kinetics of defect formation and annealing
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors

Pressure-induced amorphization of ZrTiCuNiBe bulk glass-forming alloy

Wei Hua Wang, R. J. Wang, D. Y. Dai, D. Q. Zhao, M. X. Pan, and Y. S. Yao

Appl. Phys. Lett. 79, 1106 (2001); http://dx.doi.org/10.1063/1.1396321 (3 pages) | Cited 19 times

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Zr41Ti14Cu12.5Ni10Be22.5 alloy can be cooled under high pressure (HP) to a bulky glassy state at very low cooling rates. The structure and properties of the bulk metallic glass (BMG) are investigated by differential scanning calorimetry, x-ray diffraction, ultrasonic study, and density measurements. The effects of pressure on the glass formation are discussed from the points of view of nucleation kinetics and thermodynamics. The BMG obtained under HP is in a high-density amorphous state that is different in structure and property from low-density amorphous phase quenched in water. Solidification under HP is a promising way not only for synthesizing BMGs with more densely packed structures and different properties, but also for understanding the glass formation mechanism. © 2001 American Institute of Physics.
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61.43.Fs Glasses
62.50.-p High-pressure effects in solids and liquids
62.65.+k Acoustical properties of solids
81.30.Fb Solidification

Ultrathin PtSi layers patterned by scanned probe lithography

E. S. Snow, P. M. Campbell, M. Twigg, and F. K. Perkins

Appl. Phys. Lett. 79, 1109 (2001); http://dx.doi.org/10.1063/1.1394167 (3 pages) | Cited 6 times

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A process for patterning ultrathin layers of PtSi with high spatial resolution is presented. In this process, scanned probe anodic oxidation is used to pattern a surface oxide layer on a H-passivated Si surface. This oxide pattern prevents the reaction of a deposited Pt film with the underlying Si in the formation of PtSi. The unreacted Pt on the oxide is removed by a selective etch before any annealing. This process greatly reduces lateral diffusion and produces a 2-nm-thick PtSi layer with good electrical properties that maintains the fidelity of the patterned oxide mask. Such nanostructured PtSi films are a good candidate for use in constructing lateral Si-based quantum devices. © 2001 American Institute of Physics.
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81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
85.35.Ds Quantum interference devices
85.40.Ls Metallization, contacts, interconnects; device isolation
81.16.Ta Atom manipulation
81.16.Pr Micro- and nano-oxidation

High-pressure x-ray diffraction of icosahedral Zr–Al–Ni–Cu–Ag quasicrystals

J. Z. Jiang, K. Saksl, H. Rasmussen, T. Watanuki, N. Ishimatsu, and O. Shimomara

Appl. Phys. Lett. 79, 1112 (2001); http://dx.doi.org/10.1063/1.1394951 (3 pages) | Cited 11 times

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The effect of pressure on the structural stability of icosahedral Zr–Al–Ni–Cu–Ag quasicrystals forming from a Zr65Al7.5Ni10Cu7.5Ag10 metallic glass with a supercooled liquid region of 44 K has been investigated by in situ high-pressure angle-dispersive x-ray powder diffraction at ambient temperature using synchrotron radiation. The icosahedral quasicrystal structure is retained up to the highest hydrostatic pressure used (approximately 28 GPa) and is reversible after decompression. The bulk modulus at zero pressure and its pressure derivative of the icosahedral Zr–Al–Ni–Cu–Ag quasicrystal are 99.10±1.26 GPa and 4.25±0.16, respectively. The compression behavior of different Bragg peaks is isotropic and the full width at half maximum of each peak remains almost unchanged during compression, indicating no anisotropic elasticity and no defects in the icosahedral Zr–Al–Ni–Cu–Ag quasicrystals induced by pressure. © 2001 American Institute of Physics.
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61.44.Br Quasicrystals

Bulk diffusion of microwave plasma activated deuterium into undoped natural diamond

A. Laikhtman, A. Hoffman, and C. Cytermann

Appl. Phys. Lett. 79, 1115 (2001); http://dx.doi.org/10.1063/1.1394169 (3 pages) | Cited 5 times

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In the present work undoped natural (100)-, (111)-, and (110)-oriented diamonds were exposed to microwave deuterium plasma. Secondary ion mass spectroscopy (SIMS) in static mode showed that surface deuterium concentration is the highest for (110) surface and the lowest one for (100)-oriented diamond. SIMS depth profile measurements unambiguously revealed the bulk diffusion of deuterium in the concentration of 1020–1021 atoms/cm3. Relative bulk concentrations of deuterium in the three differently oriented diamonds retained those on the surface. The measured diffusion length of deuterium is ∼0.6 μm. These results support previously performed theoretical calculations and enlighten the data obtained from absolute quantum photoyield measurements of hydrogenated natural diamond recently reported by us. © 2001 American Institute of Physics.
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66.30.J- Diffusion of impurities
81.05.U- Carbon/carbon-based materials
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
52.77.Dq Plasma-based ion implantation and deposition
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
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Suppression of lateral fluctuations in CdSe-based quantum wells

E. Kurtz, M. Schmidt, M. Baldauf, S. Wachter, M. Grün, H. Kalt, C. Klingshirn, D. Litvinov, A. Rosenauer, and D. Gerthsen

Appl. Phys. Lett. 79, 1118 (2001); http://dx.doi.org/10.1063/1.1394172 (3 pages) | Cited 5 times

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We report a reduction of inhomogeneous broadening in CdSe-related quantum wells in ZnSe by employing a growth technique that uses a CdS-compound source instead of the standard Cd elemental source for molecular-beam epitaxy. Assisted by the low sticking coefficient of sulfur and possibly an exchange reaction between S and Se, only a small S contamination is observed. A comparison with standard layers reveals an increase in quality and homogeneity by a strong reduction of the photoluminescence (PL) linewidth. Samples obtained by our method show extremely little lateral confinement as indicated by a lack of sharp single dot emission lines in micro PL and the absence of the extensive redshift observed in temperature dependent PL of fluctuating well potentials. © 2001 American Institute of Physics.
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81.07.St Quantum wells
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Et II-VI semiconductors
81.05.Dz II-VI semiconductors
78.67.De Quantum wells

Observation of thermally activated conduction at a GaN–sapphire interface

C. Mavroidis, J. J. Harris, M. J. Kappers, N. Sharma, C. J. Humphreys, and E. J. Thrush

Appl. Phys. Lett. 79, 1121 (2001); http://dx.doi.org/10.1063/1.1395525 (3 pages) | Cited 15 times

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Temperature-dependent differential Hall measurements have been performed on an undoped GaN epitaxial layer grown by metalorganic chemical vapor deposition on a sapphire substrate. The resultant depth profile shows that, for this sample, the epitaxial material is mostly insulating, and that the observed thermally activated conduction arises from an interface region ⩽0.65 μm thick. Comparison with cross-sectional transmission electron microscope micrographs suggests that this conducting region is correlated to the highly defective three-dimensional growth region, while the two-dimensional growth mode beyond this thickness corresponds to the insulating portion with a lower dislocation density. Such behavior is consistent with the presence of an impurity band in a heavily doped interface region formed by oxygen outdiffusion from the substrate. © 2001 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
73.61.Ey III-V semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.20.Pa Thermoelectric and thermomagnetic effects
73.50.Lw Thermoelectric effects
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Bias stress in organic thin-film transistors and logic gates

S. J. Zilker, C. Detcheverry, E. Cantatore, and D. M. de Leeuw

Appl. Phys. Lett. 79, 1124 (2001); http://dx.doi.org/10.1063/1.1394718 (3 pages) | Cited 93 times

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Threshold voltage instabilities of all-organic thin-film transistors are investigated as a function of stress time and stress bias. The dominant effect is a positive threshold shift for negative gate bias stress which is explained by mobile ions drifting in the insulator when a gate field is applied. Trapping of charge carriers at the semiconductor–insulator interface plays only a minor role. Furthermore, we investigate the stress behavior of a basic logic element, an inverter. In comparison to a single transistor, we observe improved stability which arises from partial compensation of the parametric shifts during operation. © 2001 American Institute of Physics.
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85.30.Tv Field effect devices
84.30.Sk Pulse and digital circuits

Selenium-related luminescent centers in metalorganic chemical-vapor-phase deposition grown ZnSe epilayers on GaAs

X. B. Zhang, K. L. Ha, and S. K. Hark

Appl. Phys. Lett. 79, 1127 (2001); http://dx.doi.org/10.1063/1.1394949 (3 pages) | Cited 14 times

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ZnSe epilayers were grown on a (001) GaAs substrate by metalorganic chemical-vapor-phase deposition. An interruption of the Zn source (i.e., Se passivation) was purposely introduced during the growth. The optical properties of the epilayers grown were studied by photoluminescence (PL) spectroscopy. We show that Se passivation during the growth interruption introduces luminescent centers in the epilayers. Evidence of this assignment comes from the characteristic temperature and excitation wavelength dependence of the PL spectra, which are distinctly different from those of commonly observed deep-level emissions associated with the so-called self-activated centers. Moreover, the PL peak energy of the centers depends strongly on the coverage of Se: the longer the time or the higher the flow rate of the Se precursor used for the passivation, the lower the energy of its PL peak. The possible origin of this luminescence is discussed. © 2001 American Institute of Physics.
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78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.05.Dz II-VI semiconductors

Measurement of piezoelectric field and tunneling times in strongly biased InGaN/GaN quantum wells

Y. D. Jho, J. S. Yahng, E. Oh, and D. S. Kim

Appl. Phys. Lett. 79, 1130 (2001); http://dx.doi.org/10.1063/1.1396315 (3 pages) | Cited 39 times

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We have measured both spectrum- and time-resolved photoluminescence (PL) of InGaN/GaN light-emitting diode structure as a function of an external bias. From spectrum-resolved PL, we observed regions of blueshift and redshift in peak PL energies. From the bias point at which redshift begins, which we attribute to the inversion of electric field due to full compensation of the piezoelectric field (PEF), we estimate PEF to be 2.1±0.2 MV/cm. From time-resolved PL, we found the carrier lifetimes to drastically decrease (2.5 ns–2 ps) with increasing reverse bias. We attribute this decrease to escape tunneling through tilted barriers. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.21.Fg Quantum wells
78.67.De Quantum wells
78.47.-p Spectroscopy of solid state dynamics
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Predicted maximum mobility in bulk GaN

D. C. Look and J. R. Sizelove

Appl. Phys. Lett. 79, 1133 (2001); http://dx.doi.org/10.1063/1.1394954 (3 pages) | Cited 33 times

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A 300 K bulk (three-dimensional) mobility of 1245 cm2/V s has been measured in free-standing GaN. Temperature-dependent Hall-effect data on this particular sample are fitted to obtain unknown lattice-scattering parameters, as well as shallow donor (ND) and acceptor (NA) concentrations, which are ND = 6.7×1015 and NA = 1.7×1015 cm−3. Realistic values of the maximum mobility attainable in bulk GaN are then obtained by assuming two-orders-of-magnitude lower values of ND and NA, leading to a maximum 300 K mobility of 1350 cm2/V s, and a maximum 77 K mobility of 19 200 cm2/V s. © 2001 American Institute of Physics.
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72.80.Ey III-V and II-VI semiconductors
72.20.Fr Low-field transport and mobility; piezoresistance
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.20.My Galvanomagnetic and other magnetotransport effects

Long-wavelength HgCdTe negative luminescent devices

T. Ashley, N. T. Gordon, G. R. Nash, C. L. Jones, C. D. Maxey, and R. A. Catchpole

Appl. Phys. Lett. 79, 1136 (2001); http://dx.doi.org/10.1063/1.1395521 (3 pages) | Cited 12 times

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We have investigated the negative luminescent properties of a HgCdTe device, fabricated from a 1 mm diameter array of photodiodes having peak emission at a wavelength of 8.5 μm. This long-wavelength luminescence is of sufficient efficiency and area to be useful in device applications. © 2001 American Institute of Physics.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.60.Jb Light-emitting devices
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors

Effective enhancement of C54 TiSi2 phase formation with multi-thermal-shock processing at 600 °C

S. Li, Y. K. Lee, L. Zhang, W. Gao, and K. S. Lee

Appl. Phys. Lett. 79, 1139 (2001); http://dx.doi.org/10.1063/1.1382630 (3 pages)

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Enhancing C54 TiSi2 phase formation and reducing its formation temperature are two key issues in ultralarge-scale integration semiconductor industry. This work demonstrated that the formation of C54 TiSi2 phase can be effectively enhanced and the processing temperature can be reduced by 150–200 °C through multi-thermal-shock processing. The result shows that the resistivity of the TiSi2 compound decreased with increasing thermal shock frequency and consequently reached 15.90 μΩ cm at 600 °C. It is believed that the enhancement of C54 phase formation is due to the increase of internal energy of C49 crystals, which is caused by multi-thermal-shock processing. © 2001 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
64.70.K- Solid-solid transitions
62.50.-p High-pressure effects in solids and liquids
85.40.Ls Metallization, contacts, interconnects; device isolation
73.61.At Metal and metallic alloys
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Coercivity and squareness enhancement in ball-milled hard magnetic–antiferromagnetic composites

J. Sort, J. Nogués, S. Suriñach, J. S. Muñoz, M. D. Baró, E. Chappel, F. Dupont, and G. Chouteau

Appl. Phys. Lett. 79, 1142 (2001); http://dx.doi.org/10.1063/1.1392308 (3 pages) | Cited 28 times

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The room-temperature coercivity, HC, and squareness, MR/MS (remanence/saturation magnetizations), of permanent magnet, SmCo5 powders have been enhanced by ball milling with antiferromagnetic NiO (with Néel temperature, TN = 590 K). This enhancement is observed in the as-milled state. However, when the milling of SmCo5 is carried out with an antiferromagnet with TN below room temperature (e.g., for CoO, TN = 290 K), the coercivity enhancement is only observed at low temperatures after field cooling through TN. The ferromagnetic–antiferromagnetic exchange coupling induced either by local heating during milling (SmCo5+NiO) or field cooling (SmCo5+CoO) is shown to be the origin of the HC increase. © 2001 American Institute of Physics.
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75.50.Ww Permanent magnets
75.50.Ee Antiferromagnetics
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
75.30.Et Exchange and superexchange interactions
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Stacked Josephson junctions in view of macroscopic quantum experiments

C. Granata, V. Corato, A. Monaco, B. Ruggiero, M. Russo, and P. Silvestrini

Appl. Phys. Lett. 79, 1145 (2001); http://dx.doi.org/10.1063/1.1391238 (3 pages) | Cited 16 times

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We present Nb/AlOx/Nb–Al/AlOx/Nb stacked Josephson junctions which we propose as three-terminal elements to control the quantum behavior of Josephson complex systems. A bias current can be independently injected in the “top” junction, providing a fine control of the critical current of the “bottom” junction. The reported characterization of the device refers to data in the classical limit including measurements of the switching dynamics between metastable states of the system at different temperatures and bias conditions. At low temperature, the effective dissipation of the bottom junction remains substantially unchanged when different injection currents flow in the top junction. These results are interesting to project new configurations of macroscopic quantum experiments. © 2001 American Institute of Physics.
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74.50.+r Tunneling phenomena; Josephson effects
85.25.Cp Josephson devices
74.25.Sv Critical currents
85.25.Dq Superconducting quantum interference devices (SQUIDs)
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