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2 Jan 1989

Volume 54, Issue 1, pp. 1-85

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Ultrafast carrier dynamics in modified semiconductor‐doped glass

J. P. Zheng and H. S. Kwok

Appl. Phys. Lett. 54, 1 (1989); http://dx.doi.org/10.1063/1.100824 (3 pages) | Cited 29 times

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The recombination lifetime in CdSx Se1−x semiconductor‐doped glass was measured by time‐resolved photoluminescence. It was found that long‐term exposure of the glass to high‐intensity laser pulses produced a permanent reduction of the free‐carrier lifetime from 80 ps to less than 10 ps. This change could be reversed by thermal annealing and should have applications to ultrafast optical signal processing.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.55.Et II-VI semiconductors
42.70.-a Optical materials

Ablation of polytetrafluoroethylene (Teflon) with femtosecond UV excimer laser pulses

S. Küper and M. Stuke

Appl. Phys. Lett. 54, 4 (1989); http://dx.doi.org/10.1063/1.100831 (3 pages) | Cited 105 times

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Experiments on the ablation of undoped polytetrafluoroethylene (Teflon) with 300 fs UV excimer laser pulses at 248 nm are reported for the first time. In contrast to standard excimer laser pulses, these ultrashort pulses ablate Teflon with good edge quality and no signs of thermal damage for fluences down to 0.5 J/cm2 with removal rates on the order of 1 μm per pulse.
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79.20.Ds Laser-beam impact phenomena
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Enhancing the 10.6 μm absorptivity of copper and aluminum using excimer laser radiation

G. Kinsman and W. W. Duley

Appl. Phys. Lett. 54, 7 (1989); http://dx.doi.org/10.1063/1.100839 (3 pages) | Cited 5 times

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Increasing absorption of 10.6 μm laser radiation by Cu and Al surfaces pretreated with excimer laser pulses has been measured. The effective coupling is shown to approach 100% under certain irradiation conditions. This increased absorption arises from a combination of excimer roughening and oxidation.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.05.Bx Metals, semimetals, and alloys
68.35.B- Structure of clean surfaces (and surface reconstruction)

Quaternary quantum wells for electro‐optic intensity and phase modulation at 1.3 and 1.55 μm

J. E. Zucker, I. Bar‐Joseph, B. I. Miller, U. Koren, and D. S. Chemla

Appl. Phys. Lett. 54, 10 (1989); http://dx.doi.org/10.1063/1.100821 (3 pages) | Cited 37 times

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We demonstrate for the first time that large quantum‐confined Stark effect can be obtained in high quality InGaAsP/InP quantum well p‐i‐n heterostructures. The compositional flexibility of this material system is particularly suited for quantum well device applications in optical communications systems operating between 1.55 and 1.3 μm. We measure the magnitude of the shift of the ground‐state exciton transition with applied electric field and find that it is significantly enhanced over ternary wells. We have also determined the electro‐optic intensity and phase modulation response in these structures.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
42.79.Hp Optical processors, correlators, and modulators

Ultraviolet optical parametric oscillation in β‐BaB2O4

W. R. Bosenberg, L. K. Cheng, and C. L. Tang

Appl. Phys. Lett. 54, 13 (1989); http://dx.doi.org/10.1063/1.101434 (3 pages) | Cited 40 times

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We report the operation of a β‐BaB2O4 singly resonant optical parametric oscillator broadly tunable in the ultraviolet, visible, and infrared regions of the spectrum. This optical parametric oscillator was pumped at 266 nm and was continously tunable throughout 0.33–1.37 μm. A novel cavity design was implemented which has applicability to other parametric oscillators. The oscillation threshold of this device was measured and compared to the calculated result.
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07.60.-j Optical instruments and equipment
42.79.-e Optical elements, devices, and systems

Very high speed GaInAs metal‐semiconductor‐metal photodiode incorporating an AlInAs/GaInAs graded superlattice

O. Wada, H. Nobuhara, H. Hamaguchi, T. Mikawa, A. Tackeuchi, and T. Fujii

Appl. Phys. Lett. 54, 16 (1989); http://dx.doi.org/10.1063/1.100822 (2 pages) | Cited 29 times

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A lateral structure metal‐semiconductor‐metal photodiode has been fabricated on GaInAs, in which an AlInAs/GaInAs graded superlattice has been incorporated. This photodiode has exhibited a dark current lower than 100 nA, an internal quantum efficiency of greater than 80% at a wavelength of 1.3 μm, and a capacitance of 40 fF, all at the bias voltage of 10 V. The response speed of this photodiode has been characterized by electro‐optic sampling to exhibit a full width at half maximum of 14.7 ps.
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85.60.Dw Photodiodes; phototransistors; photoresistors
73.40.Sx Metal-semiconductor-metal structures
72.40.+w Photoconduction and photovoltaic effects

Electromigration behavior of aluminum films deposited on silicon by ionized cluster beam and other techniques

R. E. Hummel and I. Yamada

Appl. Phys. Lett. 54, 18 (1989); http://dx.doi.org/10.1063/1.100823 (3 pages) | Cited 9 times

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Electromigration experiments have been carried out on aluminum thin films which have been deposited on oxide‐free (111) silicon by employing the ‘‘ionized cluster beam’’ technique as well as other related deposition methods. It has been found that the same high electromigration resistance and film structure is obtained with or without utilizing a nozzled crucible and with or without applying ionization and acceleration voltages during deposition. The conclusions are supported by electromigration lifetime measurements, scanning electron micrographs, optical micrographs, reflective high‐energy electron diffraction, and x‐ray diffraction.
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66.30.Qa Electromigration
68.55.-a Thin film structure and morphology
73.61.At Metal and metallic alloys
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Electrostatically defined heterojunction rings and the Aharonov–Bohm effect

C. J. B. Ford, T. J. Thornton, R. Newbury, M. Pepper, H. Ahmed, D. C. Peacock, D. A. Ritchie, J. E. F. Frost, and G. A. C. Jones

Appl. Phys. Lett. 54, 21 (1989); http://dx.doi.org/10.1063/1.100818 (3 pages) | Cited 42 times

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Micron‐sized loops of high‐mobility two‐dimensional electron gas have been made on GaAs‐AlGaAs heterostructures using a novel split‐gate technique. Aharonov–Bohm oscillations of amplitude up to 20% of the device resistance have been observed at very low temperatures (T<100 mK), together with h/2e oscillations which appear to be due to interference between pairs of time‐reversed paths near B=0. The h/e period is found to vary by ∼25% with magnetic field, possibly as a result of the formation of edge states. In the quantum Hall effect, plateaus in Rxx are seen at high B due to variations in carrier concentration across the ring, which may cause backscattering of some edge states.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Analysis of strained‐layer superlattice effects on dislocation density reduction in GaAs on Si substrates

Masafumi Yamaguchi, Takashi Nishioka, and Mitsuru Sugo

Appl. Phys. Lett. 54, 24 (1989); http://dx.doi.org/10.1063/1.100819 (3 pages) | Cited 39 times

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High quality GaAs films with dislocation densities of 1–2×106 cm−2 on (100)Si substrates have been obtained for combination of strained‐layer superlattice insertion and thermal cycle growth using the metalorganic chemical vapor deposition method. In this letter, remarkable reduction effects of dislocation density in the GaAs layers due to InGaAs/GaAs and InGaAs/GaAsP strained‐layer superlattice insertion on Si have been analyzed by calculating the dislocation force exerted by the misfit due to the strained‐layer superlattice insertions. Threshold layer thickness needed for dislocation reduction and critical thickness for dislocation generation have been clarified for several strained‐layer superlattice systems.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.55.-a Thin film structure and morphology
61.72.Bb Theories and models of crystal defects

Fractional quantum Hall effect in a high‐mobility GaAs/AlxGa1−xAs multiple quantum well heterostructure

M. Shayegan, J. K. Wang, M. Santos, T. Sajoto, and B. B. Goldberg

Appl. Phys. Lett. 54, 27 (1989); http://dx.doi.org/10.1063/1.100820 (3 pages) | Cited 13 times

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We report the realization of a high mobility [μ≂4.8×105 cm2/(V s)] selectively doped GaAs/AlxGa1−xAs multiple quantum well structure with low density (ns ≂1.7×1011 cm−2 for each of the 85 wells) grown by molecular beam epitaxy. The activation energy for the fractional quantum Hall state at the Landau‐level filling factor ν=1/3 is Δ≂2 K, the highest value ever reported for any multiple quantum well structure. Such a structure is nearly ideal for studies of the thermal properties of the two‐dimensional electron system in the fractional quantum Hall regime.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.50.Dn Low-field transport and mobility; piezoresistance

Structural and optical properties of high quality InAs/GaAs short‐period superlattices grown by migration‐enhanced epitaxy

J. M. Gérard, J. Y. Marzin, B. Jusserand, F. Glas, and J. Primot

Appl. Phys. Lett. 54, 30 (1989); http://dx.doi.org/10.1063/1.101435 (3 pages) | Cited 11 times

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InAs/GaAs highly strained short‐period superlattices have been grown by migration‐enhanced epitaxy on InP(001) substrates. Such samples exhibit clearly improved structural and optical properties. X‐ray diffraction, scanning transmission electron microscopy, photoluminescence, and Raman scattering experiments have been performed to characterize an (InAs)4(GaAs)3 layer.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.55.Cr III-V semiconductors
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Dependence of the GaAs/AlGaAs superlattice ionization rate on Al content

Toshiaki Kagawa, Hidetoshi Iwamura, and Osamu Mikami

Appl. Phys. Lett. 54, 33 (1989); http://dx.doi.org/10.1063/1.100825 (3 pages) | Cited 20 times

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Al content dependence of GaAs/Alx Ga1−xAs superlattice ionization rates was studied. The electron ionization rate is enhanced when the AlGaAs of the barrier is a direct transition type. It is drastically reduced at the Γ‐X band crossover in the AlGaAs layer. The ionization rate ratio (hole to electron) as determined by excess multiplication noise measurement is reduced from a value of 0.5 at x=0.3 to 0.14 at x=0.45. At higher values of x, corresponding to the onset of indirect electron transitions, the noise is increased.
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85.60.Dw Photodiodes; phototransistors; photoresistors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
79.20.Kz Other electron-impact emission phenomena
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Low‐temperature mobility of two‐dimensional electron gas in selectively doped pseudomorphic N‐AlGaAs/GaInAs/GaAs structures

H. Ohno, J. K. Luo, K. Matsuzaki, and H. Hasegawa

Appl. Phys. Lett. 54, 36 (1989); http://dx.doi.org/10.1063/1.100826 (3 pages) | Cited 13 times

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Low‐field mobility of two‐dimensional electron gas (2DEG) in selectively doped pseudomorphic N‐Al0.3Ga0.7As/ Ga0.8In0.13As/GaAs structures was measured as a function of carrier concentration as well as a function of temperature. In order to explain the observed mobility characteristics, scattering due to clustering has been considered. It is shown that the low‐field mobility of 2DEG at low temperature (<40 K) can be explained by the scattering due to clustering together with the remote ionized impurity scattering.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Dn Low-field transport and mobility; piezoresistance
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
85.30.Tv Field effect devices

AlGaAs/GaAs heterojunction bipolar transistors with heavily C‐doped base layers grown by flow‐rate modulation epitaxy

Toshiki Makimoto, Naoki Kobayashi, Hiroshi Ito, and Tadao Ishibashi

Appl. Phys. Lett. 54, 39 (1989); http://dx.doi.org/10.1063/1.100827 (3 pages) | Cited 7 times

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AlGaAs/GaAs heterojunction bipolar transistors are fabricated using carbon‐doped p‐type GaAs base regions grown for the first time by flow‐rate modulation epitaxy. Because of the much smaller diffusion coefficient of carbon atoms in GaAs than that of beryllium and other p‐type impurities, sharp impurity profiles are achieved. The heterojunction bipolar transistors exhibited high current gains up to 40 for a base layer width of 150 nm and base doping of 2.4×1019 cm−3 . The electron lifetime in heavily carbon‐doped GaAs layers is considerably long, indicating favorable quality of heavily carbon‐doped layers.
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85.30.Pq Bipolar transistors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Solid phase epitaxial regrowth of Si1−xGex/Si strained‐layer structures amorphized by ion implantation

B. T. Chilton, B. J. Robinson, D. A. Thompson, T. E. Jackman, and J.‐M. Baribeau

Appl. Phys. Lett. 54, 42 (1989); http://dx.doi.org/10.1063/1.100828 (3 pages) | Cited 40 times

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Strained‐layer structures consisting of ∼30–35 nm Si1−xGex (x=0.16–0.29) and 33 nm Si deposited by molecular beam epitaxy on a (100)Si substrate have been amorphized by ion implantation at 40 K with 120 keV As+. Rutherford backscattering/channeling measurements using 2 MeV He+ ions have been used to measure the thickness of the amorphous layer and monitor the subsequent epitaxial regrowth occurring as a result of annealing at 560–600 °C. Angular scans across the {110} planar channels indicate that the initial crystallinity and strain was recovered for x=0.16; however, for x=0.29 crystal quality was greatly reduced and the coherency at the substrate‐alloy layer interface was destroyed.
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81.15.Np Solid phase epitaxy; growth from solid phases
68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Temperature effects on the photoluminescence of GaAs grown on Si

Y. Chen, A. Freundlich, H. Kamada, and G. Neu

Appl. Phys. Lett. 54, 45 (1989); http://dx.doi.org/10.1063/1.100829 (3 pages) | Cited 32 times

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Photoluminescence properties of as‐grown and post‐growth annealed GaAs directly grown on Si substrates by metalorganic vapor phase epitaxy are studied at various temperatures. At low temperature, three extrinsic lines and an intrinsic exciton line split by residual biaxial tensile stress are observed. The extrinsic lines give evidence of growth‐induced defects. One of these lines, involving the presence of Si acceptors, appears after post‐growth annealing (10 min at 800 °C). The biaxial stress deduced from the intrinsic lines varies with temperature; extrapolation to zero stress results in a temperature slightly below the growth temperature.
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78.55.Cr III-V semiconductors
71.55.Eq III-V semiconductors
81.40.Tv Optical and dielectric properties related to treatment conditions
71.35.-y Excitons and related phenomena

Investigation of the critical layer thickness in elastically strained InGaAs/GaAlAs quantum wells by photoluminescence and transmission electron microscopy

J.‐P. Reithmaier, H. Cerva, and R. Lösch

Appl. Phys. Lett. 54, 48 (1989); http://dx.doi.org/10.1063/1.100830 (3 pages) | Cited 34 times

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We have studied strained InGaAs quantum wells with GaAlAs barriers, grown by molecular beam epitaxy, varying In content and well thickness. Photoluminescence measurements were made at 12 K. The appearance of a characteristic additional exciton‐like photoluminescence peak indicates the transition between elastically strained and relaxed layers. This transition was also observed by the occurrence of misfit dislocations in the corresponding transmission electron microsope (TEM) images. Layer thicknesses and In content were also determined by TEM. The results give a critical layer thickness of 29±0.5 nm at an In content of 32±2%. This value lies about a factor of 3–4 above the critical layer thickness calculated by Matthews and Blakeslee [J. Cryst. Growth 27, 118 (1974)].
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Cr III-V semiconductors
68.55.-a Thin film structure and morphology
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Photoluminescence studies of GaAs grown on InP substrates by molecular beam epitaxy

D. Huang, S. Agarwala, and H. Morkoç

Appl. Phys. Lett. 54, 51 (1989); http://dx.doi.org/10.1063/1.100832 (3 pages) | Cited 10 times

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GaAs‐based field‐effect transistor structures have been grown on InP substrates with the InGaAs/GaAs strained‐layer superlattices and 1.5 μm GaAs layer as the buffer. The low‐temperature (4 K) photoluminescence (PL) from this GaAs buffer has been studied for the first time. Among five observable peaks, the excitonic transition at energy 1.513 eV and the impurity associated recombination at energy 1.483 eV have been identified with the aid of reflection, absorption, and temperature and excitation‐intensity dependent PL measurements. The peak at 1.504 eV, most probably due to an exciton bound to a defect, is greatly enhanced compared with that of homoepitaxially grown GaAs. The optical results show that GaAs films of good quality can be grown on InP substrate, which is consistent with device results.
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78.55.Cr III-V semiconductors
85.30.Tv Field effect devices
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
71.35.-y Excitons and related phenomena

Laser‐assisted photochemical etching of Hg0.8Cd0.2Te

Rachelle J. Bienstock

Appl. Phys. Lett. 54, 54 (1989); http://dx.doi.org/10.1063/1.100833 (3 pages) | Cited 7 times

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A laser‐assisted photochemically driven etching process has been developed for Hg0.8Cd0.2Te (12 μm material). It is an etch which does not melt the surface of the material or induce mercury migration. Small geometry features (vias less than 10 μm in diameter) with straight‐edged sidewalls have been produced. The etching mechanism is a photoenhanced rapid oxidation with subsequent solvation of the oxides.
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81.65.-b Surface treatments
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Efficient generation of 480 fs electrical pulses on transmission lines by photoconductive switching in metalorganic chemical vapor deposited CdTe

Martin C. Nuss, D. W. Kisker, P. R. Smith, and T. E. Harvey

Appl. Phys. Lett. 54, 57 (1989); http://dx.doi.org/10.1063/1.100834 (3 pages) | Cited 13 times

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We have generated electrical pulses of only 480 fs duration by photoconductive switching in CdTe grown by ultraviolet‐enhanced metalorganic chemical vapor deposition (MOCVD). In addition to the extremely fast switching times, MOCVD CdTe also exhibits a high mobility of 180 cm2/V s and can be grown on almost any substrate, making it ideal for integration into existing circuits and devices.
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85.60.Dw Photodiodes; phototransistors; photoresistors
84.40.Az Waveguides, transmission lines, striplines
72.40.+w Photoconduction and photovoltaic effects
84.32.Dd Connectors, relays, and switches

Tunneling escape time of electrons from a quantum well under the influence of an electric field

T. B. Norris, X. J. Song, W. J. Schaff, L. F. Eastman, G. Wicks, and G. A. Mourou

Appl. Phys. Lett. 54, 60 (1989); http://dx.doi.org/10.1063/1.100835 (3 pages) | Cited 49 times

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We have performed time‐resolved photoluminescence on GaAs/AlxGa1−xAs single quantum well structures with an electric field applied perpendicular to the well plane. The quantum wells are coupled to the GaAs continuum through a thin barrier; the escape time of the electrons in the well was measured by time‐resolved photoluminescence. The dependence of the decay time on applied bias was found to agree very well with a simple semiclassical model.
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73.40.Gk Tunneling
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.55.Cr III-V semiconductors

p‐type modulation‐doped HgCdTe

Jeong W. Han, S. Hwang, Y. Lansari, R. L. Harper, Z. Yang, N. C. Giles, J. W. Cook, J. F. Schetzina, and S. Sen

Appl. Phys. Lett. 54, 63 (1989); http://dx.doi.org/10.1063/1.100836 (3 pages) | Cited 10 times

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At North Carolina State University, we have recently employed photoassisted molecular beam epitaxy to successfully prepare p‐type modulation‐doped HgCdTe. The modulation‐doped HgCdTe samples were grown on lattice‐matched (100) CdZnTe substrates cut from boules grown at Santa Barbara Research Center. In this letter, we report details of the growth experiments and describe the structural, optical, and electrical properties that this new infrared quantum alloy of HgCdTe possesses.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.61.Ga II-VI semiconductors

Observation of a two‐dimensional hole gas in boron‐doped Si0.5Ge0.5/Ge heterostructures

G. R. Wagner and M. A. Janocko

Appl. Phys. Lett. 54, 66 (1989); http://dx.doi.org/10.1063/1.100837 (3 pages) | Cited 3 times

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The Hall mobility and magnetoresistance of Si0.5Ge0.5/Ge heterostructures grown by molecular beam epitaxy have been studied in the temperature range 1.5<T<300 K. Shubnikov–de Haas oscillations observed at T=1.5 K indicate that selective doping of the alloy with boron generates a two‐dimensional hole gas in the Ge. The oscillation period yields a surface carrier density of 2×1012 cm−2, in reasonable agreement with the value of 3×1012 cm−2 obtained by Hall measurements. The mobility at T=4.2 K in a sample with an undoped alloy setback layer of 4 nm was μH=3.2×103 cm2/V s and in other samples was found to decrease with decreasing setback layer thickness.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Novel features of rapidly quenched melts of Bi2(Ca,Sr)3Cu2O8+δ

K. B. R. Varma, K. J. Rao, and C. N. R. Rao

Appl. Phys. Lett. 54, 69 (1989); http://dx.doi.org/10.1063/1.101436 (3 pages) | Cited 22 times

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By roller quenching and water quenching melts of Bi2(Ca, Sr)3Cu2O8+δ, glasses have been obtained. These glasses exhibit two glass transitions as well as two crystallization transitions. Microwave absorption studies show the glass to be weakly superconducting at 77 K, probably due to the presence of ultramicrocrystallites. The glass on crystallization at 870 K gives the crystalline n=1 member of the homologous series Bi2(Ca, Sr)n+1CunO2n+4 and the n=2 member on annealing at 1100 K. The glass route provides a unique means of obtaining the n=2 member of the series. On prolonged annealing of the glass at 1120 K, the n=3 member seems to be formed.
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74.70.-b Superconducting materials other than cuprates
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
81.10.Fq Growth from melts; zone melting and refining
78.70.Gq Microwave and radio-frequency interactions

Anisotropic critical current density in superconducting Bi2Sr2CaCu2O8 crystals

S. Martin, A. T. Fiory, R. M. Fleming, G. P. Espinosa, and A. S. Cooper

Appl. Phys. Lett. 54, 72 (1989); http://dx.doi.org/10.1063/1.101437 (3 pages) | Cited 83 times

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Critical current densities and resistivities were measured in a single crystal of the high Tc superconductor Bi2Sr2CaCu2O8 within the ab basal plane (∥) and along the c direction (⊥). A large anisotropy in critical current density is found, Jc∥/Jc⊥≊103, in quantitative agreement with the large normal‐state resistivity anisotropy near Tc. The data provide strong evidence for a two‐dimensional layered structure of metallic planes separated by semi‐insulating barriers.
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74.70.-b Superconducting materials other than cuprates
74.25.Sv Critical currents
74.78.Fk Multilayers, superlattices, heterostructures
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