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4 Dec 1989

Volume 55, Issue 23, pp. 2377-2461

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Picosecond single‐mode pulse compression using a 1.3 μm Fabry–Perot laser diode, a dispersion‐shifted fiber, and a grating monochromator

Ryo Takahashi, Hai‐Feng Liu, Marek Osiński, and Takeshi Kamiya

Appl. Phys. Lett. 55, 2377 (1989); http://dx.doi.org/10.1063/1.102022 (3 pages) | Cited 8 times

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A single longitudinal mode optical pulse train with a full width at half maximum less than 7.2 ps was generated by compressing gain‐switched pulses from a 1.3 μm multimode laser diode using a monochromator and a dispersion‐shifted single‐mode optical fiber.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.81.Dp Propagation, scattering, and losses; solitons
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Recombination processes in quantum well lasers with superlattice barriers

P. Blood, E. D. Fletcher, C. T. Foxon, and K. Griffiths

Appl. Phys. Lett. 55, 2380 (1989); http://dx.doi.org/10.1063/1.102023 (3 pages) | Cited 1 time

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Spontaneous emission spectra from GaAs quantum well lasers grown by molecular beam epitaxy show that the radiative recombination rate in (AlAs)(GaAs) superlattice barriers is greater than in alloy barriers of the same average composition (x=0.25) due to reduction in effective gap by superlattice effects. Measurements of emission spectra as functions of temperature show that these radiative processes account for a significant part of the temperature variation of the threshold current and we estimate that the nonradiative lifetime in the superlattice barriers is an order of magnitude longer than in alloy barriers grown under similar conditions.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Widely tunable semiconductor optical fiber ring laser

Saeko Oshiba, Kiyoshi Nagai, Masato Kawahara, Akira Watanabe, and Yoshio Kawai

Appl. Phys. Lett. 55, 2383 (1989); http://dx.doi.org/10.1063/1.102024 (3 pages) | Cited 4 times

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A wide tunable optical fiber ring laser with a diffraction grating as a tuning element is demonstrated. A wide tuning range over 100 nm is achieved using a high performance traveling‐wave amplifier (TWA) as a gain medium. The TWA with a V‐grooved inner stripe structure on a p substrate (VIPS structure) has a high peak gain over 30 dB and a broad gain width of 100 nm at 16 dB. The effects of the gain of TWA and the total loss of the external ring cavity on the tuning range are also discussed.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.81.Wg Other fiber-optical devices

Mode locking of a continuous wave Nd:glass laser pumped by a multistripe diode laser

F. Krausz, T. Brabec, E. Wintner, and A. J. Schmidt

Appl. Phys. Lett. 55, 2386 (1989); http://dx.doi.org/10.1063/1.102025 (3 pages) | Cited 10 times

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The performance of a continuous wave actively mode‐locked Nd: phosphate glass laser longitudinally pumped by a multistripe diode laser is described. The laser operates at 1.054 μm; the pump threshold and the slope efficiency are found to be 120 mW and 11%, respectively. The shortest pulse duration is 7 ps, which appears to be approximately twice as short as predicted by the theory of amplitude modulation mode locking. We explain the improved performance by additional frequency modulation due to the nonlinear index of the active material.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Efficient coupling of a semiconductor laser to an optical fiber by means of a tapered waveguide on silicon

Y. Shani, C. H. Henry, R. C. Kistler, K. J. Orlowsky, and D. A. Ackerman

Appl. Phys. Lett. 55, 2389 (1989); http://dx.doi.org/10.1063/1.102290 (3 pages) | Cited 31 times

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A Si3N4 core waveguide, matched to a laser mode, is adiabatically tapered into a SiO2:P core waveguide, matched to a fiber mode. When used to couple the light from a semiconductor laser into an optical fiber, a loss of 3.1 dB is obtained, compared to a loss of 4.5 dB obtained with a lensed fiber.
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42.79.Gn Optical waveguides and couplers
42.82.-m Integrated optics
42.81.Qb Fiber waveguides, couplers, and arrays
42.60.-v Laser optical systems: design and operation

Recording of low spatial frequency gratings in photorefractive materials

T. D. Black, A. Hafiz, D. A. Larson, and R. Magnusson

Appl. Phys. Lett. 55, 2392 (1989); http://dx.doi.org/10.1063/1.102289 (2 pages) | Cited 1 time

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Recording of low spatial frequency gratings in iron‐doped LiNbO3 crystals using a single write beam by both direct contact and optical projection methods is reported. Gratings with periods in the range 50–200 μm have been produced generating up to 40 visible diffraction orders when probed with a low‐power HeNe laser. Diffraction efficiencies over 20% are achieved for the first diffraction order.
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42.79.Vb Optical storage systems, optical disks
42.79.Dj Gratings
42.70.-a Optical materials
78.20.Jq Electro-optical effects

Second‐harmonic generation of interface waves

Y. W. Mao, Y. Shui, W. Jiang, Z. Lu, and W. Wu

Appl. Phys. Lett. 55, 2394 (1989); http://dx.doi.org/10.1063/1.102026 (2 pages) | Cited 3 times

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The second‐harmonic generation of leaky waves at the interface between glass and iron has been investigated. Fundamental frequency interface waves are excited by bulk shear waves, incident at the critical angle, and the generated second‐harmonic surface waves are detected by reradiated bulk shear waves. The amplitudes of the generated second harmonic obey the square law. The second‐harmonic generation decreases sharply as the incident and detection drive deviate from the critical angle.
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68.35.Ja Surface and interface dynamics and vibrations
62.30.+d Mechanical and elastic waves; vibrations
43.25.-x Nonlinear acoustics
43.35.Pt Surface waves in solids and liquids

In situ monitoring of silicon nitride surface temperature from rotational temperature of a nitrogen molecule during rf glow discharge processing

Shin‐ichiro Ishihara, Akira Otsuka, and Seiichi Nagata

Appl. Phys. Lett. 55, 2396 (1989); http://dx.doi.org/10.1063/1.102291 (3 pages) | Cited 3 times

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The rotational temperature of a nitrogen molecule (N2) was observed to increase proportionally with the substrate‐holder temperature in a capacitively coupled rf glow discharge system. The rotational temperature, equivalent to the gas temperature, from the second positive system of the emission spectrum of N2 increased with increasing the mixing ratio of hydrogen, which correlates with the deposition rate, optical band gap, and etching rate of silicon nitride (SiNx). This technique can be used for monitoring the temperature of a SiNx surface during glow discharge processing without any damage to the plasma.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.80.Hc Glow; corona

Thermal dependence of voiding in narrow aluminum microelectronic interconnects

Timothy D. Sullivan

Appl. Phys. Lett. 55, 2399 (1989); http://dx.doi.org/10.1063/1.102027 (3 pages) | Cited 17 times

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A model for the thermal dependence of atomic flux in passivated Al/AlSi very large scale integrated interconnects is presented. The model is derived from stress‐induced alterations in the equilibrium vacancy concentration in the metal, and has an exponential form which can be interpreted as a temperature‐dependent activation energy. The flux model together with the thermal hysteresis of stress reported for thin films can be used to describe a wide range of voiding behavior.
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85.40.Ls Metallization, contacts, interconnects; device isolation
66.30.Fq Self-diffusion in metals, semimetals, and alloys
81.40.Lm Deformation, plasticity, and creep
68.35.Fx Diffusion; interface formation

Reduction of interface‐state density by F2 treatment in a metal‐oxide‐semiconductor diode prepared from a photochemical vapor deposited SiO2 film

Kohji Inoue, Masakazu Nakamura, Masanori Okuyama, and Yoshihiro Hamakawa

Appl. Phys. Lett. 55, 2402 (1989); http://dx.doi.org/10.1063/1.102292 (3 pages) | Cited 5 times

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A new technique for the reduction of the interface‐state density Nss of a metal‐oxide‐semiconductor (MOS) diode has been developed. The SiO2 film was deposited on Si from Si2 H6 and O2 by direct photochemical vapor deposition (CVD) using vacuum ultraviolet (VUV) light of a D2 lamp. The new technique is a F2 treatment of the Si surface prior to the deposition of SiO2 film. Typically, 5% F2 gas diluted in He was introduced into the CVD chamber at 20 Pa for 5 min under UV light irradiation. The minimum value of the Nss was ∼5×109 cm−2 eV−1 at the Si midgap for the film deposited at 180 °C.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.De Semiconductor-device characterization, design, and modeling
81.65.-b Surface treatments

Effects of post‐nitridation anneals on radiation hardness in rapid thermal nitrided gate oxides

G. Q. Lo, D. K. Shih, W. Ting, and D. L. Kwong

Appl. Phys. Lett. 55, 2405 (1989); http://dx.doi.org/10.1063/1.102028 (3 pages) | Cited 5 times

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Effects of post‐nitridation anneals on radiation hardness of metal‐oxide‐semiconductor (MOS) capacitors with rapid thermal nitrided (RTN) gate oxides have been studied. Post‐nitridation anneals consisted of either rapid thermal reoxidation (RTO) in pure O2 or rapid thermal anneals (RTA) in pure N2 ambient. The radiation was performed by exposing devices to x rays at doses of 0.5–5.0 Mrad (Si). Comparing RTO and RTA anneals at the same temperature and time for given nitrided oxides, it was found that RTO enhanced the radiation hardness while RTA in N2 had detrimental effects, in terms of interface‐state generation (ΔDit) and flatband voltage shift (ΔVfb). The strainless interfacial oxide regrowth during RTO of RTN oxides is responsible for the enhanced interface ‘‘hardness’’ of RTN/RTO oxides. A physical mechanism is described to account for the observation.
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81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
68.35.Gy Mechanical properties; surface strains
62.20.Qp Friction, tribology, and hardness
61.80.Cb X-ray effects

Selective deposition of in situ doped polycrystalline silicon by rapid thermal processing chemical vapor deposition

T. Y. Hsieh, H. G. Chun, and D. L. Kwong

Appl. Phys. Lett. 55, 2408 (1989); http://dx.doi.org/10.1063/1.102029 (3 pages) | Cited 6 times

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Selective polycrystalline silicon was successfully deposited and in situ doped wih arsenic for the first time by rapid thermal processing chemical vapor deposition (RTPCVD). The growth kinetics of SiH2Cl2/AsH3/H2 gas system have been studied by examining the dependence of growth rate on deposition temperature, volume percentage of SiH2Cl2, and AsH3 mole fraction. Submicron polycrystalline silicon layers with excellent selectivity and precise thickness control have been achieved with proper deposition conditions. The growth rate decreases as doping levels increase, and drastically decreases when the AsH3 mole fraction is higher. In addition, the growth rate is linearly proportional to the SiH2Cl2 flow rate for a fixed AsH3 flow rate.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.-a Thin film structure and morphology

Decomposition of trimethylgallium in the downstream region of a near afterglow plasma

T. Sheng, B. Pihlstrom, Z. Yu, and G. J. Collins

Appl. Phys. Lett. 55, 2411 (1989); http://dx.doi.org/10.1063/1.102030 (3 pages) | Cited 6 times

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The downstream region of a near afterglow plasma (Δt=100 μs) has been used to decompose trimethylgallium (TMGa) and the products analyzed using a mass spectrometer. The major TMGa dissociation products with a hydrogen plasma were identified as methane and ethane while with a helium plasma ethane, ethylene, and acetylene were the main dissociation species. Time‐resolved optical emission originating from the downstream reaction zone shows that decomposition of TMGa occurs primarily via photodissociation with the hydrogen plasma while both photon and metastable species (He 21 S and 23 S) contributed to the TMGa decomposition with the helium plasma. VUV transmitting and VUV absorbing windows placed between the upstream hydrogen plasma and the downstream TMGa source provided further direct evidence of the role of VUV photodissociation in the TMGa decomposition.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.50.Dg Plasma sources
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
82.80.-d Chemical analysis and related physical methods of analysis

Capacitance properties in n‐type AlxGa1−xAs

I. Izpura, E. Muñoz, G. Hill, J. Roberts, M. A. Pate, P. Mistry, and N. Y. Hall

Appl. Phys. Lett. 55, 2414 (1989); http://dx.doi.org/10.1063/1.102031 (3 pages) | Cited 19 times

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The electrical properties of n‐type AlxGa1−x As, for x>0.2, are governed by deep donor states (formerly called DX centers) created by the isolated donor atoms. We have studied the capacitance properties of such layers for Si and Sn dopants. The meanings of the capacitance‐voltage carrier profiling and of the capacitance dependence with temperature have been considered. The deep donor energy position with respect to the Γ minimum has been determined.
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73.61.Ey III-V semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.30.+y Surface double layers, Schottky barriers, and work functions

Voltage tunable quantum well infrared detector

S. R. Parihar, S. A. Lyon, M. Santos, and M. Shayegan

Appl. Phys. Lett. 55, 2417 (1989); http://dx.doi.org/10.1063/1.102032 (3 pages) | Cited 37 times

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Measurements on a single quantum well infrared detector with its peak responsivity at 5.3 μm show a large Stark shift under bias. The detector has one graded barrier to enhance the effect of an electric field on the subband spacing. Several times greater change in the intersubband transition energy with applied field is obtained this way compared to the square well. Calculations show an even larger Stark shift possible with a stepped well structure.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
81.65.-b Surface treatments
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Organometallic vapor phase epitaxial growth and characterization of InAsBi and InAsSbBi

K. Y. Ma, Z. M. Fang, D. H. Jaw, R. M. Cohen, G. B. Stringfellow, W. P. Kosar, and D. W. Brown

Appl. Phys. Lett. 55, 2420 (1989); http://dx.doi.org/10.1063/1.102033 (3 pages) | Cited 20 times

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InAs1−xBix with x≤0.026 and InAs1−x−ySbyBix with x≤0.017 and y≤0.096 have been successfully grown on InAs (100) oriented substrates by atmospheric pressure organometallic vapor phase epitaxy using the precursors trimethylindium, trimethylbismuth, trimethylantimony, and arsine. Good surface morphologies for both InAsBi and InAsSbBi epitaxial layers were obtained at a growth temperature of 400 °C. A key growth parameter is the V/III ratio. Only a very narrow range near 4 (considering the incomplete pyrolysis of AsH3) yields smooth InAsBi epilayers. Typical growth rates were 0.02 μm/min. X‐ray diffractometer scans show clearly resolved Kα1 and Kα2 peaks for the layer of InAs0.889Sb0.096Bi0.015 grown on an InAs substrate with a graded transition layer to accommodate the lattice parameter difference. The half widths of the peaks are comparable to those of the substrate. For the first time, photoluminescence (PL) at 10 K from these Bi‐containing alloys has been measured. The PL peak energy is seen to decrease with increasing Bi concentration at a rate of 55 meV/at. % Bi. InAsSbBi is a potential material for infrared detectors operating in the wavelength range from 8 to 12 μm.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.55.Cr III-V semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)

Space‐charge recombination in N‐AlGaAs/p+‐GaAs heterojunction diodes

T. S. Low and D. E. Mars

Appl. Phys. Lett. 55, 2423 (1989); http://dx.doi.org/10.1063/1.102272 (3 pages) | Cited 4 times

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Space‐charge recombination currents were measured in N‐AlGaAs/p+‐GaAs heterojunction diodes grown by molecular beam epitaxy (MBE) under various growth conditions. The diode epilayer structure was designed to simulate the emitter‐base junction of a heterojunction bipolar transistor.The diodes were fabricated using a fast turnaround mesa process, and their forward current‐voltage characteristics were fit to a simple model to extract the recombination current density. The space‐charge recombination decreased steeply with increasing growth temperature Ts between 560 and 610 °C, and it decreased when the As4/Ga ratio was reduced from 3 to 1. It was lower for misoriented substrates (6° off 〈100〉 toward 〈111〉A) than for 〈100〉 oriented substrates, and it decreased significantly as the result of a post‐growth anneal in the MBE system.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.Pq Bipolar transistors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Full‐wafer mapping of total and ionized EL2 concentration in semi‐insulating GaAs using infrared absorption

Steven K. Brierley and Deborah S. Lehr

Appl. Phys. Lett. 55, 2426 (1989); http://dx.doi.org/10.1063/1.102015 (3 pages) | Cited 12 times

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By combining infrared absorption data taken at two different wavelengths in the spectral region in which the native deep donor EL2 absorbs in GaAs, it is possible to determine the distribution of the total EL2 concentration and its filled fraction across a semi‐insulating GaAs substrate. The distributions of net shallow acceptor concentration and free‐electron concentration can then be deduced. Full‐wafer maps of these quantities for a semi‐insulating GaAs wafer are displayed along with Hall effect measurements which confirm the patterns observed optically.
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78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors

Thermionic emission and photoluminescence studies of the energy states of GaAs/AlAs superlattices

M. Dutta, K. K. Choi, and P. G. Newman

Appl. Phys. Lett. 55, 2429 (1989); http://dx.doi.org/10.1063/1.102016 (3 pages) | Cited 3 times

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We have performed thermionic emission measurements on doped GaAs/AlAs superlattices and photoluminescence measurements on a series of undoped GaAs/AlAs superlattices having different well widths. Using these techniques, we determined that the energy states in the GaAs wells are bounded by the Γ minimum of the AlAs barriers, and that the X minimum instead of the Γ minimum in the AlAs layer is the relevant barrier height for the current transport in our experiment. From the magnitude of the thermionic emission current, the coupling between the Γ and X states is shown to be approximately 100 times weaker than the Γ‐Γ coupling, which is consistent with the theoretical tight‐binding model.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
79.40.+z Thermionic emission

Two‐dimensional electron gas on etched GaAs sidewalls by liquid phase epitaxial regrowth

M. R. Frei and D. C. Tsui

Appl. Phys. Lett. 55, 2432 (1989); http://dx.doi.org/10.1063/1.101997 (3 pages) | Cited 8 times

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A two‐dimensional electron gas is created on the sidewalls of V grooves etched into a GaAs substrate, using the regrowth by liquid phase epitaxy of an n‐AlGaAs modulation‐doping layer. The two‐dimensional electron gas is characterized by magnetotransport measurements. The dependence on the magnetic field orientation of the Shubnikov–de Haas oscillations shows unambiguously that the two‐dimensional electron gas is on the sidewalls, not on the top of the mesas or the bottom of the grooves.
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81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
81.65.-b Surface treatments
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Laser beam deflection as a probe of laser ablation of materials

Jeffrey A. Sell, David M. Heffelfinger, Peter Ventzek, and Ronald M. Gilgenbach

Appl. Phys. Lett. 55, 2435 (1989); http://dx.doi.org/10.1063/1.102293 (3 pages) | Cited 41 times

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Helium‐neon laser beam deflection is used to study excimer laser ablation of polymers and a YBa2 Cu3 O7−x superconductor. Density gradients above pulsed laser heated or ablated samples deflect the He‐Ne laser beam and this is measured using a position sensitive detector. The technique permits the determination of the laser fluence threshold for ablation both in a vacuum and in air, and the velocity of the ablation products in a vacuum. A model of the thermal deflection at low fluence was developed which enables measurements of thermal diffusivity of the air.
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79.20.Ds Laser-beam impact phenomena
74.70.-b Superconducting materials other than cuprates

Sequential Ar‐O2 sputtering of Y2O3, BaF2, and CuO targets for preparation of Y‐Ba‐Cu‐O superconducting films without wet‐O2 annealing

M. Bhushan, A. J. Strauss, and M. C. Finn

Appl. Phys. Lett. 55, 2438 (1989); http://dx.doi.org/10.1063/1.102294 (3 pages)

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Superconducting Y‐Ba‐Cu‐O (YBCO) films have been prepared by ex situ O2 annealing of multilayer films deposited on yttria‐stabilized zirconia substrates by sequential rf diode sputtering of Y2O3, BaF2, and CuO targets, all of which are chemically stable. If sputtering is performed in an Ar ambient, the as‐deposited films contain sufficient F to require its removal by annealing in wet O2 at about 800 °C or above before the superconducting YBCO phase can be formed by annealing in dry O2. However, sputtering in an Ar‐O2 ambient greatly reduces the F content, making it possible to obtain the superconducting phase by annealing in dry O2 only. If the ambient contains about 20% O2, films with Tc (R=0)>85 K can be prepared without wet‐O2 annealing. The Ar‐O2 process therefore has the potential for in situ preparation of superconducting YBCO films.
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74.78.-w Superconducting films and low-dimensional structures
81.15.Cd Deposition by sputtering
74.70.-b Superconducting materials other than cuprates
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

High‐field critical current densities in Bi2Sr2Ca1Cu2O8+x/Ag wires

K. Heine, J. Tenbrink, and M. Thöner

Appl. Phys. Lett. 55, 2441 (1989); http://dx.doi.org/10.1063/1.102295 (3 pages) | Cited 180 times

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Bi2 Sr2 Ca1 Cu2 O8+x /Ag wires have been produced by using the ‘‘powder in tube’’ method and an appropriate annealing procedure. At 77 K these wires yield critical current densities up to 1.2×103 A/cm2 in zero magnetic field. Using ac susceptibility measurements it is shown that flux creep is limiting the critical current density at temperatures above ∼20 K. At lower temperatures flux creep becomes insignificant. At 4.2 K critical current densities up to 5.5×104 A/cm2 in zero magnetic field and up to 1.5×104 A/cm2 in a field of 26 T could be achieved, rendering possible the use of this material for very high field application.
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74.25.Sv Critical currents
74.70.-b Superconducting materials other than cuprates
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Design analysis of a high Tc superconducting microbolometer

Qing Hu and P. L. Richards

Appl. Phys. Lett. 55, 2444 (1989); http://dx.doi.org/10.1063/1.101998 (3 pages) | Cited 44 times

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We propose an antenna‐coupled microbolometer based on the resistive transition of a high Tc superconducting film as a detector for far infrared and millimeter waves. Such microbolometers can be mechanically stronger, more easily fabricated, and much faster than conventional bolometric infrared detectors. A design analysis shows that a noise equivalent power of 2.5×10−12 W Hz−1/2 is achievable for modulation frequencies up to 10 kHz. The superconducting film must be of high quality with narrow resistive transition and low 1/f  noise.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates

Synthesis of YBa2Cu3O7−x from a soluble Y‐Ba‐Cu precursor

M. W. Rupich, B. Lagos, and J. P. Hachey

Appl. Phys. Lett. 55, 2447 (1989); http://dx.doi.org/10.1063/1.102296 (3 pages) | Cited 21 times

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The synthesis of the superconducting YBa2Cu3O7−x from a soluble, molecular precursor with the composition Cu3O3Ba2Y(meOEt)7 (meOEt is 2‐methoxyethoxide) is described. The precursor was synthesized from the reaction of a soluble copper (II) oxide polymer with alkoxides of barium and yttrium. Pyrolysis and oxidation of the precursor resulted in the formation of oriented sheets of the orthorhombic YBa2Cu3O7−x phase. The orientation in the bulk YBa2Cu3O7−x is believed to result from the presence of linear Cu‐O‐Cu‐O chains in the precursor. Bulk YBa2Cu3O7−x, prepared from the precursor, had an onset transition temperature of 92.5 K and zero resistance at 89.5 K.
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74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
74.70.-b Superconducting materials other than cuprates
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
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