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25 Sep 1989

Volume 55, Issue 13, pp. 1273-1365

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Scaling relations for strained‐layer relaxation

Brian W. Dodson and Jeffrey Y. Tsao

Appl. Phys. Lett. 55, 1345 (1989); http://dx.doi.org/10.1063/1.101594 (3 pages) | Cited 6 times

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Scaling relations for relaxation in strained‐layer structures, based on simple descriptions of the dominant relaxation mechanisms and the influence of a stress‐dependent relaxation activation energy, are obtained for general III‐V semiconductor alloys. As a result, strained‐layer relaxation in a given material system can be predicted over a wide range of structural parameters and temperature history based on a single relaxation measurement. This scaling treatment should prove useful in optimization of practical strained‐layer device structures.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.35.Gy Mechanical properties; surface strains
62.20.Hg Creep
81.40.Lm Deformation, plasticity, and creep

Demonstration of large peak‐to‐valley current ratios in InAs/AlGaSb/InAs single‐barrier heterostructures

J. R. Söderström, D. H. Chow, and T. C. McGill

Appl. Phys. Lett. 55, 1348 (1989); http://dx.doi.org/10.1063/1.101595 (3 pages) | Cited 27 times

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We report large peak‐to‐valley current ratios in InAs/AlxGa1−xSb/InAs single‐barrier tunnel structures. The mechanism for single‐barrier negative differential resistance (NDR) has been proposed and demonstrated recently. A peak‐to‐valley current ratio of 3.4 (1.2) at 77 K (295 K), which is substantially larger than what has been previously reported, was observed in a 200‐Å‐thick Al0.42Ga0.58Sb barrier. A comparison with a calculated current‐voltage curve yields good agreement in terms of peak current and the slope of the NDR region. The single‐barrier structure is a candidate for high‐speed devices because of expected short tunneling times and a wide NDR region.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Gk Tunneling
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
85.30.De Semiconductor-device characterization, design, and modeling

Thermogravimetric study of the recovery of oxygen‐deficient superconducting YBa2Cu3O7−δ oxides in ambient oxygen

L. T. Shi and K. N. Tu

Appl. Phys. Lett. 55, 1351 (1989); http://dx.doi.org/10.1063/1.102474 (3 pages) | Cited 9 times

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The oxides of oxygen‐deficient YBa2Cu3O7−δ with δ≂0.32 in both powder and chunk form were annealed in ambient oxygen to investigate the behavior of oxygen indiffusion. Thermogravimetric measurements were used to monitor in situ weight gain during the annealing at constant heating rates between room temperature and 580 °C. The temperature for achieving a definite oxygen stoichiometry changes with the heating rates, which were varied from 0.1 to 15 °C/min. By measuring the rate dependence, the activation energy of oxygen diffusion in the powder oxide was determined to be 1.25±0.05 eV, in good agreement with the value obtained by previous resistivity measurements. However, the activation energy obtained from the chunk oxide is higher, i.e., 1.52±0.06 eV. A longer diffusion distance in the chunk oxide which requires diffusion across grains might be responsible for this discrepancy.
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66.30.J- Diffusion of impurities
74.70.-b Superconducting materials other than cuprates
61.50.Nw Crystal stoichiometry
81.40.Rs Electrical and magnetic properties related to treatment conditions

Lattice defects and flux pinning in crystallized metal‐oxide glasses in the Bi‐Sr‐Ca‐Cu‐O system

Donglu Shi, J. G. Chen, U. Welp, Mark S. Boley, and A. Zangvil

Appl. Phys. Lett. 55, 1354 (1989); http://dx.doi.org/10.1063/1.101896 (3 pages) | Cited 10 times

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Large amounts of lattice defects have been observed in the crystallized metal‐oxide glasses in the Bi‐Sr‐Ca‐Cu‐O system prepared by the rapid solidification method. The density of such defects has been found to greatly increase as the calcium and copper content of the starting material increases. These lattice defects are formed as a result of supersaturation of calcium and copper in the sample matrix. The intragrain critical current density has been found to increase 30 times in magnitude as the density of the lattice defects is increased in the sample matrix. The corresponding flux pinning mechanisms are discussed.
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74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
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
61.72.-y Defects and impurities in crystals; microstructure

Microwave surface resistance in Tl‐based superconducting thin films

L. D. Chang, M. J. Moskowitz, R. B. Hammond, M. M. Eddy, W. L. Olson, D. D. Casavant, E. J. Smith, M. Robinson, L. Drabeck, and G. Grüner

Appl. Phys. Lett. 55, 1357 (1989); http://dx.doi.org/10.1063/1.102475 (3 pages) | Cited 15 times

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We report measurements of microwave surface resistance in Tl‐based superconductor thin films made by laser ablation followed by a post‐deposition thermal process. The films were measured by using cavity methods. The data at 9.5 and 148 GHz indicate that the residual resistance scales as f2. At 77 K, the 9.5 GHz surface resistance is ten times smaller than oxygen‐free high‐conductance copper at the same temperature and frequency. The 9.5 GHz measurement also indicates that the film‐substrate interface does not cause more microwave loss than the film surface.
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74.78.-w Superconducting films and low-dimensional structures
74.25.N- Response to electromagnetic fields
73.25.+i Surface conductivity and carrier phenomena
74.70.-b Superconducting materials other than cuprates

Low‐temperature annealing effect of as‐grown Bi‐Sr‐Ca‐Cu‐O thin films on superconducting property and the c‐axis lattice constant

S. Miura, T. Yoshitake, T. Manako, Y. Miyasaka, N. Shohata, and T. Satoh

Appl. Phys. Lett. 55, 1360 (1989); http://dx.doi.org/10.1063/1.101897 (3 pages) | Cited 12 times

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As‐grown crystallized Bi2Sr2Ca1Cu2Ox phase films were prepared on MgO(100) substrates by rf magnetron sputtering. The as‐grown film showed the Tc onset of 92 K and the Tc end of 82 K. By annealing in the furnace at 480 °C after deposition, superconducting property and the c‐axis lattice constant varied with atmosphere during annealing. The film after annealing in air at 480 °C exhibited the highest superconducting transition with the Tc onset of 93 K and the Tc end of 85 K. The Tc onset increased when the c‐axis lattice constant was increased, suggesting that the Tc onset increases with decreasing the oxygen content of the film.
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74.78.-w Superconducting films and low-dimensional structures
68.55.-a Thin film structure and morphology
81.40.Rs Electrical and magnetic properties related to treatment conditions
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition

22.8% efficient silicon solar cell

Andrew W. Blakers, Aihua Wang, Adele M. Milne, Jianhua Zhao, and Martin A. Green

Appl. Phys. Lett. 55, 1363 (1989); http://dx.doi.org/10.1063/1.101596 (3 pages) | Cited 67 times

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A new silicon solar cell structure, the passivated emitter and rear cell, is described. The cell structure has yielded independently confirmed efficiencies of up to 22.8%, the highest ever reported for a silicon cell.
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84.60.Jt Photoelectric conversion
85.60.Dw Photodiodes; phototransistors; photoresistors
72.40.+w Photoconduction and photovoltaic effects
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