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28 Jan 1991

Volume 58, Issue 4, pp. 319-431

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Native‐oxide stripe‐geometry AlxGa1−xAs‐GaAs quantum well heterostructure lasers

J. M. Dallesasse and N. Holonyak

Appl. Phys. Lett. 58, 394 (1991); http://dx.doi.org/10.1063/1.104645 (3 pages) | Cited 63 times

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Data are presented on the room‐temperature continuous (cw) operation of native‐oxide single‐stripe AlxGa1−xAs‐GaAs quantum well heterostructure (QWH) lasers. The device quality native oxide is produced by the conversion of high Al composition AlxGa1−xAs (x∼0.8) confining layers via H2O vapor oxidation (400 °C) in a N2 carrier gas. The 10‐μm‐wide cw 300 K QWH lasers, which are fabricated by simplified processing, have excellent spectral quality and have been operated to powers in excess of 100 mW per facet.
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42.55.Px Semiconductor lasers; laser diodes
68.55.-a Thin film structure and morphology
78.30.Fs III-V and II-VI semiconductors

Thermal annealing of modulation‐doped Si/SiGe heterostructures with high electron mobilities

F. Schäffler and H. Jorke

Appl. Phys. Lett. 58, 397 (1991); http://dx.doi.org/10.1063/1.104646 (3 pages) | Cited 10 times

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We grew n‐type modulation‐doped Si/SiGe multiple quantum well structures with the highest electron mobilities reported so far for this heterosystem. The samples were annealed at temperatures between 750 and 950 °C for 1000 s and subsequently characterized by their Hall mobilities and carrier concentrations. Only a moderate decrease in room‐temperature mobility is observed up to annealing temperatures of 900 °C. At 950 °C the samples turn more or less into homogeneously doped SiGe alloys. The annealing effects are discussed in terms of dopant and Ge diffusion, and of metastability of the SiGe layers.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Dn Low-field transport and mobility; piezoresistance
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Phonon study of strained InGaAs layers

O. Brafman, D. Fekete, and R. Sarfaty

Appl. Phys. Lett. 58, 400 (1991); http://dx.doi.org/10.1063/1.104647 (3 pages) | Cited 17 times

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Relaxation of strain in InxGa1−xAs layers on GaAs is studied by Raman spectroscopy for layers below and above the critical thickness. We show that the enormous strain of the perfect epitaxial layer is released stepwise with the thickness. It is suggested that dislocations formed at the layer surface impose the growth of the next sublayer of partially released strain, preserving the former grown sublayer of higher strain.
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63.50.-x Vibrational states in disordered systems
78.30.Fs III-V and II-VI semiconductors

Morphological stability of facet growth on nonplanar substrates

C. Ratsch and A. Zangwill

Appl. Phys. Lett. 58, 403 (1991); http://dx.doi.org/10.1063/1.104648 (3 pages) | Cited 9 times

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We study the morphological stability of layer growth by chemical vapor deposition onto a nonplanar substrate patterned with a facetted groove. Our analytic treatment indicates that, except under conditions of very modest supersaturation, diffusion effects in the gas phase generally preclude the stable growth of crystallographic facets that form the sidewalls of the groove. Instead, heterogeneous nucleation and the kinetics of step flow combine to promote the evolution of an initially perfect facet into a stably propagating vicinal surface. Under more diffusion‐limited conditions, even these ‘‘facets’’ do not survive and a characteristic rough morphology results.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.10.Bk Growth from vapor
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Scanning tunneling microscopy comparison of GaAs(001) vicinal surfaces grown by molecular beam epitaxy

M. D. Pashley, K. W. Haberern, and J. M. Gaines

Appl. Phys. Lett. 58, 406 (1991); http://dx.doi.org/10.1063/1.104649 (3 pages) | Cited 95 times

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We report the first scanning tunneling microscope observations of molecular beam epitaxy grown GaAs(001) vicinal surfaces cut 2° towards (111)A and 2° towards (111)B. The A‐type step edges are found to be relatively straight, with 16 Å kinks occurring typically every 100 Å along the step. In contrast, the B‐type step edges are found to be very ragged. On both surfaces, the terrace widths varied considerably. The details of the two step structures are dominated by the structure of the (2×4) unit cell.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Superconducting whiskers and crystals of the high Tc Bi2Sr2Ca2Cu3O10 phase

Ichiro Matsubara, Hideo Tanigawa, Toru Ogura, Hiroshi Yamashita, Makoto Kinoshita, and Tomoji Kawai

Appl. Phys. Lett. 58, 409 (1991); http://dx.doi.org/10.1063/1.105224 (3 pages) | Cited 19 times

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Whiskers of the high Tc Bi2Sr2Ca2Cu3O10  (2223) phase have been prepared by annealing Bi2Sr2CaCu2O8  (2212) whiskers in a Bi2Sr2Ca4Cu6Pb0. 5Ox powder. By the same method, single‐crystal sheets of the 2212 phase have also been converted to the 2223 phase, resulting in 2223 sheet crystals as large as approximately 1 mm2. Although the original sample outlines are retained after the phase conversion, the smooth surfaces were lost due to contact with the powder during annealing. A zero‐resistance temperature of 107 K and a maximum Jc value of 7.3×104 A/cm2 at 77 K in a zero magnetic field were obtained for the 2223 whisker.
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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
68.35.B- Structure of clean surfaces (and surface reconstruction)

X‐ray characterization of in‐plane ordering in YBa2Cu3O7−x thin films using a standard Weissenberg camera

A. Perrin, M. G. Karkut, M. Guilloux‐Viry, and M. Sergent

Appl. Phys. Lett. 58, 412 (1991); http://dx.doi.org/10.1063/1.104650 (3 pages) | Cited 10 times

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We have used a standard Weissenberg camera in the oscillating mode to characterize the in‐plane structure of YBa2Cu3O7 thin films. We find that for films optimally grown on (100) MgO or (100) SrTiO3 substrates, the in‐plane film axes are aligned parallel to the substrate axes. This is true both for solely c‐axis oriented films (perpendicular to the film plane) and for mixed a‐ and c‐axis oriented films. For a film grown on (110) SrTiO3, we have established that the film orientation perpendicular to the film plane is solely (103) and not (110) or a mixture of the two. In addition the in‐plane film axes are colinear to the substrate axes.
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68.55.-a Thin film structure and morphology
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates

Enhanced flux creep in Nb‐Ti superconductors after an increase in temperature

R. W. Cross and R. B. Goldfarb

Appl. Phys. Lett. 58, 415 (1991); http://dx.doi.org/10.1063/1.104651 (2 pages) | Cited 1 time

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The magnetic fields of Superconducting Super Collider (SSC) dipole magnets change with time when the magnets are operated at constant current. The decay of the field is thought to be a consequence of flux creep in the Nb‐Ti filaments in the superconducting cables. However, measured magnetic relaxation of small samples of SSC cable as a function of time is unlike the large decays that are observed in the fields of the actual magnets. We have made relaxation measurements on sample SSC conductors at 3.5 and 4.0 K after field cycling. The decay at both temperatures was 2.8% in 50 min. However, the relaxation measured after a temperature increase from 3.5 to 4.0 K was 4.8% in 50 min. A likely reason for the greater magnetization decay is that, after an increase in temperature, the Nb‐Ti is in a supercritical state, with shielding currents flowing at a density greater than the new critical current density. This causes enhanced flux creep. We suggest that a small temperature rise during the operation of SSC magnets may contribute to the unexpectedly large magnetic field decay.
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74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Ha Magnetic properties including vortex structures and related phenomena
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)

Lower temperature post‐annealing of thin films of YBa2Cu3O7 at lower oxygen partial pressure

A. Mogro‐Campero and L. G. Turner

Appl. Phys. Lett. 58, 417 (1991); http://dx.doi.org/10.1063/1.104654 (2 pages) | Cited 21 times

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Thin films of YBa2Cu3O7 formed by ambient temperature deposition and furnace post‐annealing have been obtained at annealing temperatures around 750 °C and an oxygen partial pressure of 29 Pa. The zero resistance transition temperature of these smooth films on LaAlO3 was 89 K, and a critical current density in excess of 1 MA cm−2 at 77 K was found by transport measurements.
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74.78.-w Superconducting films and low-dimensional structures
74.25.Sv Critical currents
74.70.-b Superconducting materials other than cuprates

Growth of YBa2Cu3O7−x thin films on Si with a CoSi2 buffer layer

Li Luo, R. E. Muenchausen, C. J. Maggiore, J. R. Jimenez, and L. J. Schowalter

Appl. Phys. Lett. 58, 419 (1991); http://dx.doi.org/10.1063/1.104655 (3 pages) | Cited 13 times

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By using the pulsed laser deposition technique, high‐temperature superconducting YBa2Cu3O7−x (YBCO) films were grown on Si(001) with a 36 nm single‐crystal 〈001〉 oriented CoSi2 buffer layer. The films, grown at a substrate temperature of ∼700 °C, have a metallic resistive temperature dependence with zero resistance at 85 K. X‐ray diffraction, scanning electron microscopy, and ion channeling studies show that the YBCO films are polycrystalline but are strongly c‐axis oriented normal to the Si substrate. Diffusion at the interface between the YBCO film and silicide buffer layer was minimized. This is essential to the growth of high‐temperature superconducting films on Si substrates.
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74.78.-w Superconducting films and low-dimensional structures
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
73.61.At Metal and metallic alloys

Water protective surface layer on fluorozirconate glass produced by low‐energy oxygen ion implantation

Yisheng Dai, Toshiyasu Kawaguchi, Koichi Suzuki, Susumu Suzuki, Kiyoshi Yamamoto, and Akio Masui

Appl. Phys. Lett. 58, 422 (1991); http://dx.doi.org/10.1063/1.104656 (3 pages) | Cited 3 times

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Fluorozirconate glass with the composition of 53ZrF4‐20BaF2‐4LaF3‐3AlF3‐20NaF was implanted with 15 keV oxygen ions to the dose of 2×1017ions/cm2. The surface layer modified by the implantation exhibited excellent chemical durability against aqueous corrosion although it showed little influence on visible and infrared transmission of the glass. X‐ray photoelectron spectroscopy measurement indicated that the zirconium on the implanted glass surface was oxidized and the fluorine was incorporated in an oxyfluoride structure. This chemically stable oxyfluoride layer prevented the glass from being corroded by water.
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61.72.up Other materials
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
61.80.Jh Ion radiation effects
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients

Radiation hardened metal‐oxide‐semiconductor devices with gate dielectrics grown by rapid thermal processing in O2 with diluted NF3

J. Ahn, G. Q. Lo, W. Ting, D. L. Kwong, John Kuehne, and Charles W. Magee

Appl. Phys. Lett. 58, 425 (1991); http://dx.doi.org/10.1063/1.104657 (3 pages) | Cited 8 times

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Radiation‐hardened, fluorinated gate oxides have been obtained by rapid thermal processing of silicon in O2 with diluted NF3. Diluted NF3 is used as a source of fluorine and is introduced during the initial stage of rapid thermal processing. It is found that optimum amounts of fluorine incorporated at the Si/SiO2 interface improve resistance against x‐ray radiation; however, excessive amounts of fluorine degrade the radiation hardness.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.40.Rs Electrical and magnetic properties related to treatment conditions
61.80.Cb X-ray effects

Permanent increase of the electrical conductivity of polymers induced by ultraviolet laser radiation

M. Schumann, R. Sauerbrey, and M. C. Smayling

Appl. Phys. Lett. 58, 428 (1991); http://dx.doi.org/10.1063/1.104624 (3 pages) | Cited 38 times

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When polyimide (Kapton) or polybenzimidazole (PBI) are irradiated by a 248 nm KrF laser, their electrical conductivity is increased permanently. Conductivity increases of up to fifteen orders of magnitude were observed, and conductivities on the order of 1–10 Ω−1 cm−1 were obtained. The laser‐induced conductivity increase of polyimide depends on the fluence per laser shot and the total fluence delivered (dosage) and exhibits a fluence threshold of ∼20 mJ cm−2 per laser shot, as well as a dosage threshold.
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72.80.Sk Insulators
73.61.Ng Insulators
78.66.Qn Polymers; organic compounds
81.40.Rs Electrical and magnetic properties related to treatment conditions
FREE

Erratum: Emission spectroscopy during excimer laser ablation of graphite [Appl. Phys. Lett. 57, 2178 (1990)]

Xiangli Chen and Jyoti Mazumder

Appl. Phys. Lett. 58, 431 (1991); http://dx.doi.org/10.1063/1.105247 (1 page)

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Abstract Unavailable
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78.40.Ha Other nonmetallic inorganics
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
33.20.Kf Visible spectra
99.10.Cd Errata
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