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1 Aug 1988

Volume 53, Issue 5, pp. 347-452

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Demonstration of an AlGaAs/GaAs integrable optical correlator using surface‐emitting second‐harmonic generation

Daryoosh Vakhshoori and Shyh Wang

Appl. Phys. Lett. 53, 347 (1988); http://dx.doi.org/10.1063/1.99910 (3 pages) | Cited 11 times

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A broadband optical correlator with the potential for integration is demonstrated in a GaAs/AlGaAs waveguide for the first time. The correlator uses the surface emission of a coherently generated second‐harmonic signal propagating perpendicularly to the direction of propagation of the fundamental beam. While the fundamental pulse propagates back and forth in a waveguide cavity, it emits a second‐harmonic signal normal to the top surface of the waveguide. The variation of this second‐harmonic signal across the waveguide cavity yields the pulse width of the fundamental beam. Using this technique, a pulse width of 7 ps is measured for a 100 μW(140 mW) average (peak) power of a compressed mode‐locked neodymium:yttrium aluminum garnet laser in a GaAs/AlGaAs ridge waveguide cavity. This integrable technique of correlation has the potential of measuring subpicosecond pulses.
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42.79.Gn Optical waveguides and couplers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Nonplanar index‐guided quantum well heterostructure periodic laser array

C. A. Zmudzinski, M. E. Givens, R. P. Bryan, and J. J. Coleman

Appl. Phys. Lett. 53, 350 (1988); http://dx.doi.org/10.1063/1.99911 (3 pages) | Cited 6 times

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Data are presented on nonplanar index‐guided quantum well heterostructure periodic laser arrays grown by metalorganic chemical vapor deposition (MOCVD). The nonplanar array structure, formed by a single MOCVD growth over a selectively etched corrugated substrate, not only provides index guiding for the individual array elements, but also suppresses lateral lasing and amplified spontaneous emission for the entire array. As a result, the entire width of the device is utilized for optical emission, and no additional processing steps are required. Devices tested exhibit uniform emission and show no signs of lateral lasing or amplified spontaneous emission for array widths up to 3.3 times the cavity length. The processing required for device fabrication is therefore minimized by taking advantage of the properties of MOCVD growth over nonplanar substrates.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.60.Jb Light-emitting devices
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Free‐electron laser based on the effect of channeling in an intense standing light wave

M. V. Fedorov, K. B. Oganesyan, and A. M. Prokhorov

Appl. Phys. Lett. 53, 353 (1988); http://dx.doi.org/10.1063/1.99912 (2 pages) | Cited 4 times

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Channeling of electrons moving across an intense standing light wave is described. This effect is proposed to be used for the creation of a free‐electron laser. Its linear gain is found and estimated.
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41.60.Cr Free-electron lasers
37.10.Vz Mechanical effects of light on atoms, molecules, and ions

Liquid‐sodium thermoacoustic engine

A. Migliori and G. W. Swift

Appl. Phys. Lett. 53, 355 (1988); http://dx.doi.org/10.1063/1.99913 (3 pages) | Cited 9 times

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We have constructed a thermoacoustic engine that uses liquid sodium as its working substance. The engine generates acoustic power using heat flowing from a high‐temperature source to a low‐temperature sink. The measured performance of this engine disagrees significantly with numerical calculations based on our theory of thermoacoustic engines. The efficiency of the engine is a substantial fraction of Carnot’s efficiency, and its power density is comparable to that of the conventional heat engines in widespread use. Thus we expect this type of engine to be of practical, economic importance.
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84.60.Rb Thermoelectric, electrogasdynamic and other direct energy conversion
43.20.+g General linear acoustics
47.15.Cb Laminar boundary layers

Electron yield of glow discharge cathode materials under helium ion bombardment

B. Szapiro, J. J. Rocca, and T. Prabhuram

Appl. Phys. Lett. 53, 358 (1988); http://dx.doi.org/10.1063/1.100401 (3 pages) | Cited 19 times

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The secondary electron emission coefficient of materials for helium ion bombardment in the energy range 0.5–20 keV was measured for the surface conditions of cathodes in high voltage glow discharges. The materials studied are oxidized aluminum, oxidized magnesium, a molybdenum‐aluminum oxide sintered composite, molybdenum, stainless steel, copper, gold, and graphite. Each sample was surface conditioned by operating it as cathode of a helium glow discharge shortly before the electron yield measurement. The results are relevant to the modeling of glow discharges and the design of cold cathode electron guns.
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41.75.Fr Electron and positron beams
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
52.80.Hc Glow; corona

Low‐temperature deposition of zirconium and hafnium boride films by thermal decomposition of the metal borohydrides (M[BH4]4)

A. L. Wayda, L. F. Schneemeyer, and R. L. Opila

Appl. Phys. Lett. 53, 361 (1988); http://dx.doi.org/10.1063/1.100603 (3 pages) | Cited 19 times

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Conductive (150 μΩ cm), adherent films of zirconium and hafnium borides have been deposited on various substrates by the low‐temperature (100–270 °C) thermal decomposition of Zr[BH4]4 and Hf[BH4]4. Auger electron spectroscopy of these films shows that their composition is ZrB2 and HfB2. The film surfaces are oxidized and slightly carbon contaminated. However, the bulk contains less than 1 at. % C or O. This synthesis is by far the lowest temperature preparation of these materials (plasma‐enhanced chemical vapor deposition of TiB2 requires 480–600 °C) and holds great promise for the use of these materials in electronics applications.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.Nq Composition and phase identification
79.20.Fv Electron impact: Auger emission

Low‐temperature silicon epitaxy by low‐energy bias sputtering

T. Ohmi, K. Matsudo, T. Shibata, T. Ichikawa, and H. Iwabuchi

Appl. Phys. Lett. 53, 364 (1988); http://dx.doi.org/10.1063/1.99914 (3 pages) | Cited 21 times

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Bias sputtering at low energies, i.e., comparable to typical crystal interatomic binding energies, has been utilized to control the kinetics of thin‐film growth. It was found that the crystallographic structures of sputter‐deposited silicon films are drastically changed by the energy of ions incident at the substrate. As a result, formation of high quality epitaxial silicon films on (100) silicon substrates has been realized at such low temperatures as 320–350 °C. At the same time, low‐temperature impurity doping of the epitaxial layer has been also demonstrated. Furthermore, the low‐energy bias sputtering process has made it possible to perform very effective substrate surface cleaning at extremely low temperatures without introducing any damage to the substrate.
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68.55.Nq Composition and phase identification
81.15.Cd Deposition by sputtering

Surface‐field‐induced tunnel junctions on InAs

U. Kunze and W. Kowalsky

Appl. Phys. Lett. 53, 367 (1988); http://dx.doi.org/10.1063/1.99896 (3 pages) | Cited 8 times

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We report on tunneling between the two‐dimensional electron inversion layer on a degenerate p‐InAs substrate and the three‐dimensional bulk valence states in Yb/oxide/InAs tunnel junctions. The current‐voltage characteristics show negative differential conductance with current peak‐to‐valley ratio up to 2.7 (17) at T=300 K (77 K). The inversion layer is induced by the high electric surface field that arises from the low work function of the Yb electrode. Tunneling across the oxide provides a low‐resistive contact of the metal to the electron layer.
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73.40.Gk Tunneling
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Impurity gettering by misfit dislocations in Si (2% Ge) epitaxy: nickel

D. M. Lee, J. B. Posthill, F. Shimura, and G. A. Rozgonyi

Appl. Phys. Lett. 53, 370 (1988); http://dx.doi.org/10.1063/1.99897 (3 pages) | Cited 12 times

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The microstructure associated with nickel gettering by an epitaxial misfit dislocation network generated in Si(2% Ge) chemical vapor deposition films has been determined using transmission electron microscopy. The configuration of misfit dislocations is a well‐characterized network of b=a/2〈011〉 60° dislocations that all lie in the (001) interfacial plane. Nickel was deliberately introduced by deposition onto the front surface of the wafer followed by diffusion at temperatures from 600 to 1000 °C. Nickel segregated on or in the immediate vicinity of the misfit dislocations to form individual or agglomerates of fine precipitates. The strong temperature dependence of Ni solubility in Si and the nucleation enhancement by the localized strain effects in the vicinity of dislocations are considered to be the dominant factors controlling gettering by the misfit dislocations. An annealing temperature of 600 °C is suggested which appears to uniformly decorate the misfit dislocations with Ni for possible buried microwire applications.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
64.75.-g Phase equilibria
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Yx Interaction between different crystal defects; gettering effect

Electron transport in heterostructure hot‐electron diodes

D. Arnold, K. Hess, and G. J. Iafrate

Appl. Phys. Lett. 53, 373 (1988); http://dx.doi.org/10.1063/1.99898 (3 pages) | Cited 17 times

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Vertical electron transport in GaAs/AlxGa1−xAs heterostructures is investigated through Monte Carlo simulations of the heterostructure hot‐electron diode (HHED). A fully self‐consistent ensemble Monte Carlo algorithm with a realistic numerical band structure is employed. Results show that transport in the HHED is dominated by the influence of the heterointerface closest to the emitting contact. Two distinct modes of conduction are observed. One is a low‐conductivity regime where transport is predominantly by gamma valley tunneling. The other is a high‐conductivity regime where transport is mainly due to thermionic emission of electrons from the GaAs to the AlxGa1−xAs. In the latter most of the electrons are in the L and X valleys when they transfer to the wide‐gap material. In these valleys the propagation from GaAs to AlxGa1−xAs is virtually unimpeded as the band‐edge discontinuities are small in contrast to the situation for gamma electrons.
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85.30.De Semiconductor-device characterization, design, and modeling
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
73.50.Mx High-frequency effects; plasma effects

Memory phenomena in heterojunction structures: Evidence for suppressed thermionic emission

Fabio Beltram, Federico Capasso, John F. Walker, and Roger J. Malik

Appl. Phys. Lett. 53, 376 (1988); http://dx.doi.org/10.1063/1.100400 (3 pages) | Cited 8 times

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The physics of a new GaAs/AlGaAs floating‐gate memory device is investigated. Long electron storage times (e.g., 4 h at 140 K) have been measured and linked to the indirect nature of the GaAs‐AlAs conduction‐band discontinuity. A simple analysis of the structure shows that scattering‐assisted tunneling processes and band‐structure effects, not included in standard thermionic emission theories, must be considered to properly account for the observed long retention times.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
79.40.+z Thermionic emission

Characterization of interfacial atomic steps in GaAs/AlAs superlattices by transmission electron microscopy

T. Nakamura, M. Ikeda, S. Muto, and I. Umebu

Appl. Phys. Lett. 53, 379 (1988); http://dx.doi.org/10.1063/1.99899 (3 pages) | Cited 11 times

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We have studied interfacial atomic steps in GaAs/AlAs superlattices using high‐resolution transmission electron microscopy (HRTEM) and lattice image simulation. We find arrays of bright spots at the interface in the TEM image to be good indicators of the interface configuration. Doubling of the bright spot arrays and step‐shaped arrays in TEM lattice images indicate a ‘‘type 1’’ monolayer step whose front is perpendicular to the direction of the electron beam and a ‘‘type 2’’ monolayer step whose front is parallel to the direction of the electron beam. Our HRTEM observations indicate that the atomic steps at GaAs and AlAs interfaces grown at 700 °C are denser than at interfaces grown at 500 °C.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Local modes of vibration in proton‐ and deuteron‐implanted InP

J. Tatarkiewicz, B. Clerjaud, D. Côte, F. Gendron, and A. M. Hennel

Appl. Phys. Lett. 53, 382 (1988); http://dx.doi.org/10.1063/1.99900 (3 pages) | Cited 21 times

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The results of optical absorption experiments on proton‐ and deuteron‐implanted indium phosphide are reported. It is shown that these implantations produce two types of hydrogen‐ (or deuterium‐) related defects. These defects also exist in as‐grown material not intentionally doped with hydrogen. The nature of these two defects is discussed.
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61.72.J- Point defects and defect clusters
61.72.U- Doping and impurity implantation
63.20.Pw Localized modes
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors

Picosecond switching time measurement of a resonant tunneling diode

J. F. Whitaker, G. A. Mourou, T. C. L. G. Sollner, and W. D. Goodhue

Appl. Phys. Lett. 53, 385 (1988); http://dx.doi.org/10.1063/1.99886 (3 pages) | Cited 51 times

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Picosecond bistable operation has been experimentally observed for the first time in a double‐barrier resonant tunneling diode. A rise time of 2 ps was measured using the electro‐optic sampling technique; this is the fastest switching event yet observed for an electronic device. This time domain measurement adds necessary information to the understanding of the transport mechanisms in the resonant tunneling diode and is consistent with switching time limitations computed for the device. It also demonstrates that appropriately designed double‐barrier quantum well diodes have a response time comparable to that of the fastest all‐optical logic elements, and that they may be very useful in high‐speed logic applications.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Noninvasive optical probe of free charge and applied voltage in GaAs devices

U. Keller, S. K. Diamond, B. A. Auld, and D. M. Bloom

Appl. Phys. Lett. 53, 388 (1988); http://dx.doi.org/10.1063/1.99887 (3 pages) | Cited 3 times

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We have demonstrated an application of a noninvasive optical probe that can independently measure both free sheet charge density and applied voltage in GaAs devices. Large‐signal direct‐current measurements of voltage and charge were made on a Schottky diode without any assumption of the device parameters. The measurements are reproducible, and no adjustable parameters have been used to quantitatively measure charge and voltage. In addition to a lateral charge resolution, given by the beam spot size, we have observed a longitudinal resolution due to the standing wave in the probe beam.
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85.30.De Semiconductor-device characterization, design, and modeling
07.60.Ly Interferometers
77.22.Ch Permittivity (dielectric function)

Tunneling measurement of the density of states of a superlattice

P. England, J. R. Hayes, J. P. Harbison, D. M. Hwang, and L. T. Florez

Appl. Phys. Lett. 53, 391 (1988); http://dx.doi.org/10.1063/1.99888 (3 pages) | Cited 11 times

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We have studied the current‐voltage characteristics of GaAs/AlGaAs samples consisting of an electron injector, a wide AlGaAs tunnel barrier, and a strongly coupled superlattice. The bias determines the energy of electrons injected into the superlattice, and the resulting tunnel current shows pronounced structure associated with minibands and band gaps. The position of the bands is in quantitative agreement with theory, and we resolve minibands with energies both below and above the AlGaAs conduction‐band offset.
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73.40.Gk Tunneling
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

Nature of misfit dislocation sources in strained‐layer semiconductor structures

Brian W. Dodson

Appl. Phys. Lett. 53, 394 (1988); http://dx.doi.org/10.1063/1.99889 (3 pages) | Cited 26 times

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It is currently possible to grow nearly perfect strained‐layer semiconductor heterostructures. Experimental evidence shows that misfit dislocation sources become active almost immediately as the layer thickness exceeds the equilibrium critical thickness. These dislocation sources do not seem related to obvious causes, such as threading dislocations or homogeneous nucleation at surface structures. It is argued here that the dislocation sources are inhomogeneous in nature and result from local stress concentrations near the surface.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
61.72.Lk Linear defects: dislocations, disclinations

Heteroepitaxial growth of InP on a GaAs substrate by low‐pressure metalorganic vapor phase epitaxy

H. Horikawa, Y. Ogawa, Y. Kawai, and M. Sakuta

Appl. Phys. Lett. 53, 397 (1988); http://dx.doi.org/10.1063/1.99890 (3 pages) | Cited 25 times

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Good quality InP was successfully grown on (100)GaAs 2° off normal toward [011] substrates by introducing low‐temperature grown GaAs/InP double buffer layers. It was found that addition of a thin GaAs buffer layer (20 nm thick) grown at low temperature (430 °C) between the GaAs substrate and an InP buffer layer was effective for improving the crystal quality. The full width at half‐maximum of the x‐ray rocking curve was as narrow as 200 arcsec for a 6‐μm‐thick InP layer. An electron mobility of 15 000 cm2/(V s) at 77 K was obtained for an unintentionally doped layer. The intensity of the photoluminescence at 77 K was as good as that for an InP substrate.
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81.10.Bk Growth from vapor

Epitaxial growth of ZrN on Si(100)

S. A. Barnett, L. Hultman, J.‐E. Sundgren, F. Ronin, and S. Rohde

Appl. Phys. Lett. 53, 400 (1988); http://dx.doi.org/10.1063/1.99891 (3 pages) | Cited 14 times

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Epitaxial ZrNx (x=1.0±0.05) films have been grown on Si(100) substrates using reactive magnetron sputtering. The films were deposited from a Zr sputtering target in a pure N2 discharge with a growth rate of 700 nm/h and substrate temperatures Ts=750 and 900 °C. X‐ray diffractometer results showed complete (100) preferred orientation for both temperatures. Transmission electron microscopy (TEM) observations for samples grown at Ts=750 °C indicated that the (100) grains were almost randomly oriented about the surface normal, but that a small fraction of epitaxial grains were present. Electron channeling and TEM showed that ZrN films were epitaxial for Ts=900 °C. The epitaxial relationships were found to be ZrN(100)//Si(100) and ZrN[011]//Si[011]. The resistivity of the films was 25–35 μΩ cm.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering

Transient photocapacitance and photocurrent studies of undoped hydrogenated amorphous silicon

A. V. Gelatos, K. K. Mahavadi, J. D. Cohen, and J. P. Harbison

Appl. Phys. Lett. 53, 403 (1988); http://dx.doi.org/10.1063/1.99892 (3 pages) | Cited 17 times

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We have applied transient photocapacitance and transient junction photocurrent measurements to the study of undoped hydrogenated amorphous silicon (a‐Si:H) films, and find that the electronic optical transition from the dominant deep defect is very similar in energy to the D−→D0+e optical transition identified in n‐type doped a:Si:H films. In addition, we have observed a competing hole thermal transition, and we have obtained estimates of its thermal emission rate and of the thermal gap. We have used the difference between photocapacitance and photocurrent in the valence‐band tail region to determine the quantity (μτ)hNT at different temperatures. Finally, we have observed that light‐induced metastable defects have a hole capture cross section significantly larger than that of the intrinsic defects.
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78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
72.40.+w Photoconduction and photovoltaic effects
71.55.Ht Other nonmetals
72.80.Ng Disordered solids

Sequential electron beam evaporated films of Tl2CaBa2Cu2Oy with zero resistance at 97 K

D. S. Ginley, J. F. Kwak, R. P. Hellmer, R. J. Baughman, E. L. Venturini, and B. Morosin

Appl. Phys. Lett. 53, 406 (1988); http://dx.doi.org/10.1063/1.100604 (3 pages) | Cited 50 times

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Thin unoriented polycrystalline films in the Tl‐Ca‐Ba‐Cu‐O system were prepared by sequential electron beam evaporation of multiple Tl, Ca, Ba, and Cu layers and a two‐stage anneal under controlled Tl and oxygen overpressures. These films show zero resistance as high as 97 K and transport critical current densities at 76 K up to 110 000 A/cm2 with typical values of 50 000 A/cm2. The critical currents exhibit a modest magnetic field dependence. Meissner effect data show an onset at 110 K and a superconducting fraction of 75%. Compositional and structural studies indicate that the films, although polyphase, are predominantly Tl2Ca1Ba2Cu2Oy. There is no evidence of other superconducting phases.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
74.25.Sv Critical currents
74.78.-w Superconducting films and low-dimensional structures
79.20.Kz Other electron-impact emission phenomena

Influence of short coherence length on the superconducting proximity effect of silicon‐coupled junctions

M. Hatano, T. Nishino, F. Murai, and U. Kawabe

Appl. Phys. Lett. 53, 409 (1988); http://dx.doi.org/10.1063/1.99893 (3 pages) | Cited 6 times

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Superconducting critical currents of NbN‐Si‐NbN and Nb‐Si‐Nb junctions with a coplanar structure are measured as a function of temperature and of the spacing between superconducting electrodes. The current decreases exponentially with increasing temperature above 4.2 K and with increasing spacing. It is found that the coherence length in the semiconductor is determined only by the physical properties of the semiconductor, even though the superconducting electrode with a short coherence length such as NbN is used. Moreover, the measured coherence length in Si agrees with the value derived from the model of Seto and Van Duzer [J. Low Temp. Phys. LT‐13, 323 (1972)].
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74.50.+r Tunneling phenomena; Josephson effects
74.25.Sv Critical currents
74.10.+v Occurrence, potential candidates
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)

Superconducting R‐Ba‐Cu‐O balls made by rapid solidification

Yiping Li and G. C. Hadjipanayis

Appl. Phys. Lett. 53, 412 (1988); http://dx.doi.org/10.1063/1.100605 (2 pages) | Cited 2 times

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Melt spinning has been used to prepare superconducting R‐Ba‐Cu‐O compounds with R=Y, Er, Dy, and Gd. The starting materials were sintered R‐Ba‐Cu‐O samples, and most of them were not superconducting above 77 K. The melt‐spun samples had a spherical shape with a diameter in the range of 0.1–2.0 mm. The samples were annealed in air at about 900 °C for 1 h. Samples with diameter greater than 1.5 mm were found to be not superconducting. The critical temperatures were found to be in the range of 60–88 K.
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74.70.-b Superconducting materials other than cuprates
74.10.+v Occurrence, potential candidates
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Synthesis and properties of a 125 K superconductor in the Tl‐Ca‐Ba‐Cu‐O system

I. K. Gopalakrishnan, P. V. P. S. S. Sastry, K. Gangadharan, G. M. Phatak, J. V. Yakhmi, and R. M. Iyer

Appl. Phys. Lett. 53, 414 (1988); http://dx.doi.org/10.1063/1.100606 (3 pages) | Cited 8 times

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A method for the synthesis of a 125 K superconducting phase having a nominal composition TlCaBaCu2 Ox is described. It is shown that by sintering at 1200 K in flowing oxygen containing a controlled amount of water vapor, a zero electrical resistance state (Tcf) at temperatures as high as 125 K can be obtained. A transport critical current density (Jc ) of ∼240 A/cm2 at 77 K was obtained in this 125 K material.
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74.70.-b Superconducting materials other than cuprates
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
61.05.cp X-ray diffraction

Proton radiation damage in superconducting EuBa2Cu3Ox and GdBa2Cu3Ox

J. O. Willis, D. W. Cooke, R. D. Brown, J. R. Cost, J. F. Smith, J. L. Smith, R. M. Aikin, and M. Maez

Appl. Phys. Lett. 53, 417 (1988); http://dx.doi.org/10.1063/1.100607 (3 pages) | Cited 12 times

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Sintered samples of EuBa2Cu3Ox and GdBa2Cu3Ox with x≂7 have been irradiated at 90 °C with 800 MeV protons. The superconducting transition temperature decreases 1.7 K/1017 pcm−2 for both materials. The critical magnetization current density, characterizing intragranular conduction, increases a factor of 3 at zero field and relatively larger factors for finite magnetic fields at 7 and 75 K for fluences on the order of 1017 pcm−2. No and only minor differences between irradiated and unirradiated specimens were seen in calorimetric and transmission electron microscopy analyses, respectively.
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74.70.-b Superconducting materials other than cuprates
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
74.25.Ha Magnetic properties including vortex structures and related phenomena
61.80.Jh Ion radiation effects
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