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2 May 1988

Volume 52, Issue 18, pp. 1455-1543

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High‐efficiency superlattice graded‐index separate confining heterostructure lasers with AlGaAs single quantum wells

J. R. Shealy

Appl. Phys. Lett. 52, 1455 (1988); http://dx.doi.org/10.1063/1.99096 (3 pages) | Cited 8 times

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Superlattice graded‐index separate confining heterostructure lasers, with AlGaAs single quantum wells operating in the wavelength range from 700 to 845 nm, are reported. These structures have external power efficiency above 40%, which is the highest reported to date over this entire wavelength range. By examining the performance of these structures as the thin quantum well active region is alloyed with aluminum, a better understanding of the dominant loss mechanism in thin single quantum well lasers results: it is concluded from this study that the carrier population of the higher energy states in the quantum well, and of states associated with the graded‐index regions, is the dominant carrier loss mechanism which limits the device performance. The energies of these states involving direct transitions are readily observed with room‐temperature photoluminescence. They include the n=2 states of the quantum well and the confined states (n=3, 4,...) extending into graded‐index regions. Additional states resulting from the X conduction band in the graded‐index regions appear at energies near the top of the well (∼ 2 eV at room temperature) for the structures evaluated in this study. The growth of these structures and the limitations of the devices’ performance under continuous wave conditions at the shorter wavelengths are reviewed.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes

Synthesis of crafted optical pulses by time domain modulation in a fiber‐grating compressor

M. Haner and W. S. Warren

Appl. Phys. Lett. 52, 1458 (1988); http://dx.doi.org/10.1063/1.99097 (3 pages) | Cited 25 times

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We report a method for direct generation of voltage programmable, arbitrarily shaped laser pulses of subpicosecond duration and roughly 100 fs resolution. A waveguide intensity modulator was fabricated and incorporated into a fiber‐grating pulse compressor to shape temporally the chirped pulse before compression. Optical pulses with sin(x)/x and square envelopes are synthesized to demonstrate the technique.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.81.Wg Other fiber-optical devices
42.79.Gn Optical waveguides and couplers

Electro‐optical effects of externally applied 〈100〉 uniaxial stress on InGaAsP 1.3 and 1.5 μm injection lasers

V. Swaminathan, P. Parayanthal, and R. L. Hartman

Appl. Phys. Lett. 52, 1461 (1988); http://dx.doi.org/10.1063/1.99098 (3 pages) | Cited 4 times

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The changes in the polarization of the emission, spectrum, and light‐current (L‐I) behavior of a 1.3 and 1.5 μm InGaAsP channeled substrate buried heterostructure laser and double‐channel planar buried heterostructure laser under an external uniaxial compressive stress perpendicular to the junction were studied at room temperature. It was found that the TM emission (electric vector perpendicular to the junction) reached threshold even at a stress level of ∼1×108 dyn cm−2. For stress ≤4×108 dyn cm−2, the TM emission, although reaching threshold first, was found to exist only over a limited range of currents. At high currents only TE emission (electric vector parallel to the junction) was observed. The appearance of the TE emission gave rise to nonlinear L‐I characteristics. When both TM and TE emissions were seen, the former occurred at a higher energy. The limited stability of TM emission with current at low stresses is explained by invoking spectral hole burning effects which reduce the gain saturation power for TM mode than the TE mode. At high stresses ≥4×108 dyn cm−2, the increased gain for TM‐polarized light ensures its stability at all currents. From our results it can be concluded that to avoid TM emission, and the associated spectral changes and nonlinear L‐I characteristics, the tensile stress in the plane of the active layer should be less than 108 dyn cm−2.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
78.20.Jq Electro-optical effects

High‐performance InGaAsP/InP buried‐heterostructure lasers and arrays defined by ion‐beam‐assisted etching

D. Yap, Z. L. Liau, D. Z. Tsang, and J. N. Walpole

Appl. Phys. Lett. 52, 1464 (1988); http://dx.doi.org/10.1063/1.99099 (3 pages) | Cited 4 times

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Ion‐beam‐assisted etching has been used to fabricate mass‐transported InGaAsP/InP buried‐ heterostructure lasers. These lasers have a novel, deeply etched rectangular mesa that results in reduced current leakage. Both single‐stripe lasers and Y‐junction‐coupled multiple‐stripe laser arrays have been demonstrated. The single‐stripe lasers have 12 mA cw threshold currents, differential quantum efficiencies of 32%–34% per facet, and smooth single‐lobe far‐field patterns. The multiple‐stripe arrays lase in‐phase with strong phase coherence.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
81.65.-b Surface treatments

Fivefold and threefold symmetries in silver clusters

S. Giorgio and J. Urban

Appl. Phys. Lett. 52, 1467 (1988); http://dx.doi.org/10.1063/1.99100 (2 pages) | Cited 14 times

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The structures of small silver clusters supported by carbon have been determined in high‐resolution electron microscopy. Undistorted crystals displaying fivefold and threefold symmetries were found with sizes ranging from 30 to 100 Å. Such large particles displaying fivefold symmetries are generally believed to be unstable. However, in this case stabilization was achieved by shifting the center of symmetry with respect to the individual faces. The magnitude of the shift increases with the growth of the particles. The center of symmetry for particles with a threefold axis was always found to be unshifted.
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61.66.Bi Elemental solids
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Crystallinity and hardness of B+‐implanted Fe

Motohisa Hirano and Shojiro Miyake

Appl. Phys. Lett. 52, 1469 (1988); http://dx.doi.org/10.1063/1.99101 (3 pages) | Cited 3 times

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Pure Fe is implanted with B+ at a target temperature range of −20 to 300 °C. The effects of the target temperature on the crystallinity and hardness in the B+ ‐implanted Fe are investigated. It was found that Fe2B is formed by using direct B+ implantation into pure Fe without subsequent annealing. ‘‘Cold implantation,’’ where the implantation is performed at a lower target temperature, reduces crystallinity and increases the hardness of the B+ ‐implanted Fe. An increase in target temperature, therefore, renders the B+ ‐implanted Fe with high crystallinity and relatively low hardness.
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62.20.Qp Friction, tribology, and hardness
61.72.up Other materials
81.40.Pq Friction, lubrication, and wear
61.66.Bi Elemental solids

Changes in the electronic properties of bulk GaAs by thermal annealing

M. T. Asom, J. M. Parsey, L. C. Kimerling, R. Sauer, and F. A. Thiel

Appl. Phys. Lett. 52, 1472 (1988); http://dx.doi.org/10.1063/1.99102 (3 pages) | Cited 7 times

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Bulk GaAs grown by the Bridgman technique changes its electronic properties in response to heat treatment. These changes were studied by deep level transient spectroscopy, photoluminescence, and Hall effect measurements. We report the dependence of the conductivity changes on starting material composition, annealing temperature, and annealing duration. The changes are related to the stability of a shallow acceptor which is present in concentrations ≥1016 cm−3 and reflect the equilibration of native defects introduced during the crystal growth process. The implication of this study is that as‐grown GaAs is a metastable material with its ultimate electrical properties being determined by process conditions.
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81.40.Rs Electrical and magnetic properties related to treatment conditions
81.40.Tv Optical and dielectric properties related to treatment conditions
61.72.Bb Theories and models of crystal defects

Investigation of triethylarsenic as a replacement for arsine in the metalorganic chemical vapor deposition of GaAs

R. M. Lum, J. K. Klingert, A. S. Wynn, and M. G. Lamont

Appl. Phys. Lett. 52, 1475 (1988); http://dx.doi.org/10.1063/1.99103 (3 pages) | Cited 17 times

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GaAs growth experiments have been performed with triethylarsenic (TEAs) to investigate its potential as a replacement for arsine, and to compare the effects on film properties of substituting ethyl for methyl groups in alkyl arsenic sources used in metalorganic chemical vapor deposition. Films were deposited over a wide range of growth conditions (Tg=550–750 °C, V/III=2–13), and data were obtained on film electrical and optical properties and variations in growth rate. Growth with TEAs yielded films with good surface morphology, low background doping levels (<1015 cm−3) and 77 K mobilities of 13 000 cm2/V s. Although this represents a considerable improvement over films grown with trimethylarsenic, film properties still appear to be limited by unacceptably high levels of carbon incorporation. Experiments using triethylgallium as the group III source in place of trimethylgallium resulted in substantially reduced and nonuniform growth due to prereaction at the reactor walls.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.61.Ey III-V semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
68.55.-a Thin film structure and morphology

Ultrathin semiconductor layer masks for high vacuum focused Ga ion beam lithography

H. Temkin, L. R. Harriott, and M. B. Panish

Appl. Phys. Lett. 52, 1478 (1988); http://dx.doi.org/10.1063/1.99104 (3 pages) | Cited 18 times

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The application of thin semiconductor layers as etch masks for high vacuum lithography is described. Heteroepitaxial layers of In0.53Ga0.47As or InP, as thin as 30 Å, were grown by molecular beam epitaxy and patterned using a focused beam of Ga ions. The Ga ion beam exposure is very rapid, since only a small amount of the mask material needs to be removed, and readily produces features with submicron sizes. The patterned thin layer can then be used as a mask for deep, material selective etching. The feasibility of selective dry etching of InP based compounds is discussed. This combination of molecular beam epitaxy and efficient precision patterning techniques is expected to result in a new flexibility in design and fabrication of semiconductor devices.
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81.65.-b Surface treatments
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
85.40.Hp Lithography, masks and pattern transfer
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

InGaAs/InAlAs multiquantum well intersubband absorption at a wavelength of λ=4.4 μm

B. F. Levine, A. Y. Cho, J. Walker, R. J. Malik, D. A. Kleinman, and D. L. Sivco

Appl. Phys. Lett. 52, 1481 (1988); http://dx.doi.org/10.1063/1.99105 (3 pages) | Cited 69 times

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We report, for the first time, intersubband absorption experiments in doped InGaAs/InAlAs multiquantum well superlattices and observe a resonance peak at a wavelength of λ=4.4 μm which is in good agreement with theory. This material system may be useful for detectors in the λ=3–5 μm spectral region.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
85.60.Gz Photodetectors (including infrared and CCD detectors)
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ey III-V semiconductors

Gas source silicon molecular beam epitaxy using disilane

Hiroyuki Hirayama, Toru Tatsumi, and Naoaki Aizaki

Appl. Phys. Lett. 52, 1484 (1988); http://dx.doi.org/10.1063/1.99106 (3 pages) | Cited 37 times

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In gas source silicon molecular beam epitaxy (MBE) using disilane, good crystal quality silicon epitaxial films were obtained at a temperature as low as 630 °C. In comparison with gas source Si‐MBE using silane, a growth rate several times higher was attained. Boron doping in the gas source Si‐MBE was also studied. Using HBO2 as the B‐doping source, the doping level was controlled in the range of 1016–1018 cm−3 by the cell temperature. Because of the low growth temperature and the high growth rate, an abrupt doping profile was obtained.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Comparative studies of ion‐induced mixing of GaAs‐AlAs superlattices

P. Mei, T. Venkatesan, S. A. Schwarz, N. G. Stoffel, J. P. Harbison, D. L. Hart, and L. A. Florez

Appl. Phys. Lett. 52, 1487 (1988); http://dx.doi.org/10.1063/1.99107 (3 pages) | Cited 30 times

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The species dependence of ion‐induced superlattice mixing has been examined in AlAs‐GaAs superlattice samples grown by molecular beam epitaxy. The interdiffusion of the superlattices induced by ion implantation with comparable ranges, doses, and subsequent thermal anneals were measured with secondary ion mass spectrometry. The effects of elements of comparable mass (Ga, As, and Ge) and comparable valence (Si and Ge) were studied. The experimental results show that Ga and As implantation cause primarily collision‐induced mixing, while Ge implantation results in collision‐induced mixing with additional impurity‐induced mixing beyond the implant range. In comparison with Ge, Si‐induced mixing is similar in nature though there is significant difference in the depth and extent of the mixing. The extent of mixing is found to depend on the local Ge or Si concentration.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.35.Fx Diffusion; interface formation
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.80.Jh Ion radiation effects

Ytterbium monolayer diffusion barriers at Hg1−xCdxTe/Al junctions

A. Franciosi, A. Raisanen, A. Wall, S. Chang, P. Philip, N. Troullier, and D. J. Peterman

Appl. Phys. Lett. 52, 1490 (1988); http://dx.doi.org/10.1063/1.99108 (3 pages) | Cited 6 times

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Single layers of Yb at the Hg1−xCdxTe(110) interface prevent Al‐Te reaction and dramatically increase the Hg concentration at the interface. Synchrotron radiation photoemission studies of the interface as a function of Al deposition show a two orders of magnitude increase in the Hg/Te core intensity ratio as a result of the interlayer‐induced change in atomic interdiffusion. Calculations of thermodynamic parameters following a semiempirical alloying model suggest that other rare earths should also act as effective diffusion barriers at mercury‐cadmium‐telluride/reactive metal junctions.
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68.35.Fx Diffusion; interface formation
66.30.Ny Chemical interdiffusion; diffusion barriers

Be+/P+ and Be+/As+ dual implantations into AlxGa1−xAs

Shoji Yamahata and Sadao Adachi

Appl. Phys. Lett. 52, 1493 (1988); http://dx.doi.org/10.1063/1.99109 (3 pages) | Cited 13 times

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Dual implantations of Be+/P+ (Be+ and P+ ions) and Be+/As+ (Be+ and As+ ions) into Al0.3 Ga0.7 As are carried out, and electrical properties of the implanted layers are evaluated by Hall‐effect measurements. Improved electrical activity is observed for the dual implant compared with the single implant. In particular, in the case of the Be+/P+ dual implant, apparent hole concentration becomes nearly twice as high as that of the Be+ single implant at annealing temperatures above 650 °C. The dual implantation technique also greatly suppresses redistribution of Be atoms, and so Gaussian‐type profiles remain, even after high‐temperature annealing (∼950 °C).
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Elimination of interface defects in mismatched epilayers by a reduction in growth area

E. A. Fitzgerald, P. D. Kirchner, R. Proano, G. D. Pettit, J. M. Woodall, and D. G. Ast

Appl. Phys. Lett. 52, 1496 (1988); http://dx.doi.org/10.1063/1.99110 (3 pages) | Cited 36 times

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We have eliminated interface defects from the mismatched In0.05Ga0.95As/ (001)GaAs interface by controlling the size of the growth area. 2‐μm‐high pillars with different lateral shapes and dimensions were defined within the GaAs substrate before the molecular beam epitaxial growth of 3500 Å of In0.05Ga0.95As, greater than four times the critical thickness. On the pillars, the linear density of misfit dislocations was reduced from >5000 dislocations/cm for large (several hundred μm lateral dimensions) growth areas to nearly zero for 25 μm lateral dimensions. The dislocation density remains less than 800 dislocations/cm for lateral dimensions up to 100 μm. We find that there is also a decrease in dislocation density in narrow channels between the pillars; therefore, the pillars also block the glide of misfit dislocations.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.Bb Theories and models of crystal defects
68.55.-a Thin film structure and morphology

AlGaAs multiple‐wavelength light‐emitting bar grown by laser‐assisted metalorganic chemical vapor deposition

J. E. Epler, H. F. Chung, D. W. Treat, and T. L. Paoli

Appl. Phys. Lett. 52, 1499 (1988); http://dx.doi.org/10.1063/1.99111 (3 pages) | Cited 13 times

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The first optical device fabricated from epitaxial material grown by laser‐assisted crystal growth is reported. The device is an AlGaAs multiple‐wavelength light‐emitting bar in which the Al composition of the active layer, and thus the emission wavelength, varies as a function of position along the bar. The Al composition is photochemically patterned during growth with an in situ Ar+ laser beam. The energy band gap increases from a minimum of 1.475 eV to a maximum of 1.52 eV over a 4 mm section of the bar. The spatial dependence of the energy band gap is roughly Gaussian and corresponds to the laser intensity profile. The electroluminescent data are presented along with a brief discussion of the laser‐assisted crystal growth process.
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85.60.Jb Light-emitting devices
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.60.Fi Electroluminescence

Polarity determination in compound semiconductors by channeling: Application to heteroepitaxy

A. C. Chami, E. Ligeon, R. Danielou, and J. Fontenille

Appl. Phys. Lett. 52, 1502 (1988); http://dx.doi.org/10.1063/1.99112 (3 pages) | Cited 17 times

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A direct method for polarity determination of the compound semiconductor (111) face is presented. Channeling shows that the (111)B CdTe face (or Te face) corresponds to the best (111) face for further II‐VI epitaxy. Epitaxial relationships are also determined for (111)CdTe/(001) GaAs. It is determined that the (111)CdTe layer also ends up on a B face. The bond directions of Ga and As atoms are determined with respect to those of Te and Cd. These informations suggest a mechanism for such an epitaxial growth.
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68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Very shallow acceptors in neutron transmutation doped silicon

C. R. LaBrec, M. K. Udo, and A. K. Ramdas

Appl. Phys. Lett. 52, 1505 (1988); http://dx.doi.org/10.1063/1.99113 (3 pages)

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We report the far‐infrared absorption spectra of very shallow acceptor centers in silicon consisting of boron (aluminum) introduced during growth complexed with defect centers produced during neutron transmutation doping followed by a partial high‐temperature anneal. As annealing of the samples removes radiation damage and activates isolated boron (aluminum) centers, a new acceptor series, attributed to this acceptor complex, is observed with a ground‐state binding energy significantly lower than that of the known impurity.
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78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
71.55.Ht Other nonmetals
61.80.Hg Neutron radiation effects

Spatial localization of impurities in δ‐doped GaAs

E. F. Schubert, J. B. Stark, B. Ullrich, and J. E. Cunningham

Appl. Phys. Lett. 52, 1508 (1988); http://dx.doi.org/10.1063/1.99114 (3 pages) | Cited 78 times

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Capacitance‐voltage profiles on δ‐doped GaAs grown by molecular beam epitaxy reveal extremely narrow widths of ≲40 Å at room temperature. Subband structure and capacitance‐voltage (C‐V) profiles of δ‐doped GaAs are calculated self‐consistently. Experimental C‐V profiles agree with self‐consistent results, only if we assume that Si impurities are localized on the length scale of the lattice constant in the host GaAs zinc‐blende lattice.
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73.61.Ey III-V semiconductors
66.30.J- Diffusion of impurities
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Room‐temperature exciton transitions in partially intermixed GaAs/AlGaAs superlattices

J. D. Ralston, S. O’Brien, G. W. Wicks, and L. F. Eastman

Appl. Phys. Lett. 52, 1511 (1988); http://dx.doi.org/10.1063/1.99115 (3 pages) | Cited 85 times

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Substantial increases are observed in the energies of room‐temperature exciton transitions in GaAs/AlGaAs superlattices which have been partially intermixed via the impurity‐free vacancy diffusion process. Localized intermixing of the layered structure was accomplished by selective deposition of a SiO2 capping layer followed by rapid thermal annealing at temperatures between 850 and 950 °C for 15 s. In the samples studied, the above process allows continuously variable energy shifts of at least 61 meV while still maintaining clearly resolved excitonic behavior. Shifting and broadening of the exciton transitions are studied using room‐temperature photoluminescence and photocurrent spectroscopies. A transmission resonance calculation is used to determine the interdiffusion coefficient as a function of temperature from the measured energy shifts.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Cr III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Effect of bias on the response of metal‐oxide‐semiconductor devices to low‐energy x‐ray and cobalt‐60 irradiation

D. M. Fleetwood, P. S. Winokur, C. M. Dozier, and D. B. Brown

Appl. Phys. Lett. 52, 1514 (1988); http://dx.doi.org/10.1063/1.99116 (3 pages) | Cited 9 times

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The response of metal‐oxide‐semiconductor (MOS) transistors and capacitors to high‐energy Co‐60 gamma and low‐energy x‐ray irradiation is evaluated as a function of gate bias during exposure. It is demonstrated that, in contrast to previous expectations, the relative response of MOS devices to Co‐60 gamma and 10 keV x‐ray irradiation cannot be explained simply in terms of electron‐hole recombination and dose enhancement effects.
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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
61.80.Ed γ-ray effects

Ionization‐enhanced solid phase epitaxy of amorphous silicon with boron impurities

Won Woo Park, M. F. Becker, and R. M. Walser

Appl. Phys. Lett. 52, 1517 (1988); http://dx.doi.org/10.1063/1.99117 (3 pages) | Cited 14 times

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We have made the first high‐resolution, laser interferometric measurements of the functional dependence of the velocity of (100) silicon solid phase epitaxy on the concentration of implanted boron impurities NB. At all measurement temperatures (450–550 °C), and for all NB<5×1019 cm−3 the fractional increase in the velocity was identically equal to the dimensionless ratio NB/Ni, where Ni is a thermally activated factor. This result disagrees with the predictions of all models for the effect of impurities on solid phase epitaxial growth.
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81.15.Np Solid phase epitaxy; growth from solid phases
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Ion beam analysis of oxygen distribution in superconducting YBa2Cu3Ox

E. Rauhala, J. Keinonen, and R. Järvinen

Appl. Phys. Lett. 52, 1520 (1988); http://dx.doi.org/10.1063/1.99694 (3 pages) | Cited 9 times

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It has been shown that by combining the elastic scattering of protons and Rutherford scattering of α particles, the total composition and oxygen distribution of superconducting YBa2Cu3Ox films and bulk samples can be analyzed. The non‐Rutherford scattering due to the 16O(p,p0)16O reaction enhances at the bombarding energy of 2.3 MeV the elastic scattering cross section by a factor of 5 over the cross section of the Rutherford scattering and makes it possible to determine the oxygen distribution in the matrix of heavy elements Y, Ba, and Cu.
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61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
74.70.-b Superconducting materials other than cuprates
68.55.-a Thin film structure and morphology

Chemical etching of Y‐Cu‐Ba‐O thin films

I. Shih and C. X. Qiu

Appl. Phys. Lett. 52, 1523 (1988); http://dx.doi.org/10.1063/1.99695 (2 pages) | Cited 16 times

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Thin films of Y‐Ba‐Cu‐O have been deposited by rf sputtering using a stoichiometric target on alumina, zirconia, and Y2O3 coated silicon substrates. After a brief heat treatment in oxygen, a resistive transition was observed with an onset temperature from 89 to 94.6 K. Etching experiments of the as‐deposited films have been made to determine the etching rates of the compound. It was found that reproducible results can be readily obtained using the following solutions: H3PO4/H2O, HNO3/H2O, and HCl/H2O. Using a positive photoresist technology, 3 μm lines have been successfully produced by etching in these solutions. The present patterning process was found to have no deleterious effect on the superconducting characteristics of the Y‐Ba‐Cu‐O films.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments
74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates

Texture formation and enhanced critical currents in YBa2Cu3O7

M. K. Malik, V. D. Nair, A. R. Biswas, R. V. Raghavan, P. Chaddah, P. K. Mishra, G. Ravi Kumar, and B. A. Dasannacharya

Appl. Phys. Lett. 52, 1525 (1988); http://dx.doi.org/10.1063/1.99696 (3 pages) | Cited 29 times

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We report an increase of a factor up to 5 in JC on mixing varying amounts of Ag2O with YBa2Cu3O7. The increase correlates with an increase in texture as seen by x‐ray diffraction intensities. Microstructure indicates the formation of platelets with c axis normal to the platelets.
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74.25.Sv Critical currents
74.70.-b Superconducting materials other than cuprates
61.72.Mm Grain and twin boundaries
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
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