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5 Oct 1992

Volume 61, Issue 14, pp. 1613-1734

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Investigation of In0.53Ga0.47As/AlAs resonant tunneling diodes for high speed switching

D. H. Chow, J. N. Schulman, E. Özbay, and D. M. Bloom

Appl. Phys. Lett. 61, 1685 (1992); http://dx.doi.org/10.1063/1.108451 (3 pages) | Cited 14 times

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We report an investigation of In0.53Ga0.47As/AlAs resonant tunneling diodes designed for high speed switching applications. Experimental peak current densities are observed to increase with decreasing AlAs barrier thicknesses, in good agreement with a two band tunneling calculation, which includes the effects of strain and band bending. Swing voltages over the range 0.5–1.0 V are demonstrated to be controllable via the thickness of a lightly doped depletion layer. Estimated RC time constants are compared with intrinsic tunneling times for the samples studied. A sample with 6 monolayer AlAs barriers yields devices with peak current densities of 3.1×105 A/cm2 and peak‐to‐valley current ratios of 6:1. The minimum rise time in this sample is calculated to be limited by RC switching delays to 1.6 ps.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Native‐oxide defined In0.5(AlxGa1−x)0.5P quantum well heterostructure window lasers (660 nm)

S. A. Maranowski, F. A. Kish, S. J. Caracci, N. Holonyak, J. M. Dallesasse, D. P. Bour, and D. W. Treat

Appl. Phys. Lett. 61, 1688 (1992); http://dx.doi.org/10.1063/1.108452 (3 pages) | Cited 14 times

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Data are presented demonstrating In0.5(AlxGa1−x)0.5P quantum well heterostructure lasers with extended current‐blocking windows (∼75 μm/window) that exhibit significant improvements in output power (∼2×) compared to lasers with no windows. The windows and active stripes are defined by the formation of a thin (∼1000 Å, patterned) native oxide via H2O vapor oxidation (550 °C) of the high‐gap In0.5(AlxGa1−x)0.5P upper confining layer. Devices operating at ∼660 nm with a 40 μm wide emitting aperture (∼500 μm cavity) and ∼75 μm windows (total window length ∼150 μm) exhibit 300 K continuous output powers ≳130 mW/facet (uncoated) and pulsed output powers ≳575 mW/facet (uncoated). Improvements in output power result from decreased heating at the facets and defocusing of the optical wave in the unpumped window regions.
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42.55.Px Semiconductor lasers; laser diodes
42.60.-v Laser optical systems: design and operation
81.65.-b Surface treatments

Random telegraph signals arising from fast interface states in metal‐SiO2‐Si transistors

Ming‐Horn Tsai, Hirotaka Muto, and T. P. Ma

Appl. Phys. Lett. 61, 1691 (1992); http://dx.doi.org/10.1063/1.108453 (3 pages) | Cited 13 times

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Using fast sampling rates, we have been able to resolve random telegraph signals (RTSs) associated with trapping‐detrapping of channel electrons by individual fast interface states in small metal‐SiO2‐Si transistors. Possible reasons why such fast RTSs have not been reported in the past are suggested. Some characteristics of the RTSs arising from fast interface states are presented and compared with those from the slow traps.
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85.30.Tv Field effect devices
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.50.Td Noise processes and phenomena
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Excitonic electroabsorption in type II superlattices

Shaozhong Li and Jacob B. Khurgin

Appl. Phys. Lett. 61, 1694 (1992); http://dx.doi.org/10.1063/1.108454 (3 pages) | Cited 6 times

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Electric field dependence of the exciton absorption in the ZnSe0.35Te0.65‐ZnTe type II superlattice has been studied theoretically. Large effective blue shift of the absorption edge and strong modulation of the absorption prove that type II structures can be used in visible spatial light modulators and switches.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.40.Ha Other nonmetallic inorganics
42.65.Pc Optical bistability, multistability, and switching, including local field effects

Normal incidence infrared absorption in AlAs/AlGaAs x‐valley multiquantum wells

Jennifer Katz, Y. Zhang, and W. I. Wang

Appl. Phys. Lett. 61, 1697 (1992); http://dx.doi.org/10.1063/1.108455 (3 pages) | Cited 13 times

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We report the first observation of normal incidence infrared absorption due to interconduction subband transitions in AlAs/AlGaAs x‐valley multiquantum wells. Infrared absorption measurements were performed on samples grown on [111], [113], [115], and [001] substrates with normal incidence radiation at wavelengths of 5–20 μm. Two absorption peaks were observed in the [113] and [115] multiquantum wells with well widths of 40 Å and sheet doping concentrations of 1012 cm−2. One peak, due to transitions between the ground state and the continuum band occurred at 7.1 μm; a second peak originating from interconduction subband transitions between the ground state and the first excited state occurred at 17 μm. The experimental results indicate the potential of these novel structures for use as normal incidence infrared photodetectors.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors

Higher order zone‐folded modes in ZnSe‐ZnS strained‐layer superlattices

Aishi Yamamoto, Yoshihiko Kanemitsu, Yasuaki Masumoto, Shigeki Yamaga, and Akihiko Yoshikawa

Appl. Phys. Lett. 61, 1700 (1992); http://dx.doi.org/10.1063/1.108456 (3 pages) | Cited 4 times

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Higher order (up to the 5th order) zone‐folded acoustic modes in ZnSe‐ZnS strained‐layer superlattices (SLSs) were observed by means of Raman scattering. Structural characterization of both periodicity of superlattices and roughness of the interface was done by means of transmission electron microscopy (TEM). The Raman spectrum of zone‐folded modes was well explained by the theoretical calculation which takes account of two observed structural characteristics of the sample, the periodicity of the superlattices, and the roughness of the interface. This clearly shows the strain does not matter to the observation of the zone‐folded modes.
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78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
63.20.D- Phonon states and bands, normal modes, and phonon dispersion
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Optical investigations of GaAs‐GaInP quantum wells grown on the GaAs, InP, and Si substrates

Xiaoguang He and Manijeh Razeghi

Appl. Phys. Lett. 61, 1703 (1992); http://dx.doi.org/10.1063/1.108429 (3 pages) | Cited 8 times

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We report the first photoluminescence investigation of GaAs‐Ga0.51In0.49P lattice matched multiquantum wells grown by the low pressure metalorganic chemical vapor deposition simultaneously in the same run on GaAs, Si, and InP substrates. The sharp photoluminescence peaks indicate the high quality of the samples on three different substrates. The temperature dependence of the photoluminescence indicates that the intrinsic excitonic transitions dominate at low temperature and free‐carrier recombinations at room temperature. The photoluminescence peaks of the samples grown on Si and InP substrates shift about 15 meV from the corresponding peaks of the sample grown on the GaAs substrate. Two possible interpretations are provided for the observed energy shift. One is the diffusion of In along the dislocation threads from GaInP to GaAs and another is the localized strain induced by defects and In segregations.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Observation of deep‐level‐free band edge luminescence and quantum confinement in strained Si1−xGex/Si single quantum well structures grown by solid source Si molecular beam epitaxy

N. Usami, S. Fukatsu, and Y. Shiraki

Appl. Phys. Lett. 61, 1706 (1992); http://dx.doi.org/10.1063/1.108430 (3 pages) | Cited 28 times

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Well‐resolved band edge luminescence with no deep level emissions is reported for Si0.8Ge0.2/Si single quantum well (SQW) structures grown at high substrate temperatures (Ts≊620 °C) by solid source Si molecular beam epitaxy (MBE). No‐phonon (NP) transitions due to symmetry‐breaking alloy disordering in SiGe layers and transverse optical (TO) phonon replicas were clearly identified. With decreasing well width, NP and TO emissions were found to show systematic blue shift due to quantum confinement effect. Excellent crystal quality was evidenced by total absence of defect‐related deep level emissions characteristic of photoluminescence spectra of samples grown at lower temperatures, Ts<600 °C. This result indicates that high growth temperature environment is essential to efficient radiative recombination in SiGe/Si QW structures.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.55.Hx Other solid inorganic materials
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Low‐leakage superconductive tunneling in all‐YBa2Cu3O7−x edge junctions

Q. Y. Ying, C. Hilbert, and H. Kroger

Appl. Phys. Lett. 61, 1709 (1992); http://dx.doi.org/10.1063/1.108431 (3 pages) | Cited 4 times

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All‐YBa2Cu3O7−x (YBCO) superconductor‐insulator‐superconductor (SIS) edge‐type tunnel junctions have been fabricated. This leads to the observation of superconductive tunneling with very low small‐bias conductance for the first time in fabricated all‐YBCO junctions. The presence of a superconductive gap of YBCO with a complete suppression of the density of states at the Fermi surface is evident from dynamic conductance measurements. The approach to all‐YBCO SIS edge junctions is discussed.
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74.50.+r Tunneling phenomena; Josephson effects
85.25.Cp Josephson devices
74.70.-b Superconducting materials other than cuprates

Growth of the infinite layer phase of Sr1−xNdxCuO2 by laser ablation

Chunming Niu and Charles M. Lieber

Appl. Phys. Lett. 61, 1712 (1992); http://dx.doi.org/10.1063/1.108432 (3 pages) | Cited 10 times

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Pulsed laser deposition (PLD) has been used to prepare tetragonal Sr1−xNdxCuO2 thin films that have the parent structure of the high Tc copper oxide superconductors. Low‐temperature deposition using a single source target has been shown to kinetically trap c‐axis oriented, infinite layer Sr1−xNdxCuO2 materials on 〈100〉SrTiO3 substrates. In addition, electrical measurements indicate that neodymium substitution drives the system from an insulating to a weakly metallic state.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
74.70.-b Superconducting materials other than cuprates
74.78.-w Superconducting films and low-dimensional structures

Uniform and flexible 24‐meter superconducting tape of silver‐sheathed Tl0.5Pb0.5Ba0.4Sr1.6Ca2Cu3O8.2

Z. F. Ren and J. H. Wang

Appl. Phys. Lett. 61, 1715 (1992); http://dx.doi.org/10.1063/1.108433 (3 pages) | Cited 19 times

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See Also: Erratum

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Simple geometric considerations show that to maximize the transport Jc for a given type of bulk superconductor, it is only necessary to have the individual grains in the sample oriented with maximal area of close contact with their immediate neighbors. With this guideline, a 24‐meter silver‐sheathed thallium‐containing superconductor of the 1223‐type without long‐range granular alignment has been made. It is flexible, uniform, and exhibits a transport Jc of 104 A/cm2 at 77 K in the absence of external magnetic field.  
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84.71.Ba Superconducting magnets; magnetic levitation devices
74.25.Sv Critical currents
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation

Sr2AlTaO6 films for multilayer high‐temperature superconducting device applications

A. T. Findikoglu, C. Doughty, S. Bhattacharya, Qi Li, X. X. Xi, T. Venkatesan, R. E. Fahey, A. J. Strauss, and Julia M. Phillips

Appl. Phys. Lett. 61, 1718 (1992); http://dx.doi.org/10.1063/1.108408 (3 pages) | Cited 16 times

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Thin films of Sr2AlTaO6 (SAT) and multilayers of YBa2Cu3O7 (YBCO)/SAT have been grown by pulsed laser deposition on [001] LaAlO3 substrates. X‐ray diffraction shows that SAT grows on [001] LaAlO3 with the c‐axis oriented normal to the substrate plane. X‐ray rocking curve and Rutherford backscattering channeling measurements on SAT films yield full width at half maximum of <0.3° and minimum backscattering yield χmin of 5%–7%, respectively, indicating good crystallinity. The real part of the dielectric constant ϵr is found to be ∼23–30, with ∼6×107 V/m static breakdown electric field. Both the dielectric constant and the static breakdown field show negligible temperature dependence between 10 and 300 K. A 100 nm×10 μm×50 μm YBCO film on SAT shows zero‐field critical current density of ∼1.3×106 A/cm2 at 77 K, with a superconducting transition temperature Tc0 of ∼89.2 K.
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77.55.-g Dielectric thin films
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices

On the two‐dimensional superstructure in the (001) plane of Bi‐Sr‐Ca‐Cu‐O superconductors

Jian‐guo Zheng, Qi Li, Duan Feng, Feng Yu, Jian‐ming Hong, and Xian‐hui Chen

Appl. Phys. Lett. 61, 1721 (1992); http://dx.doi.org/10.1063/1.108409 (3 pages) | Cited 2 times

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The two‐dimensional (2D) superstructure in the (001) plane of Bi‐Sr‐Ca‐Cu‐O superconductor was first proposed by Marshall et al. [Appl. Phys. Lett. 53, 426 (1989)]. Some results obtained in our experiments indicate that the apparent 2D superstructure modulation pattern results from two grains with a [001] twist boundary.
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61.66.Bi Elemental solids
61.72.Mm Grain and twin boundaries
74.70.-b Superconducting materials other than cuprates

Electron tunneling into epitaxial films of Nd2−xCexCuO4−y

M. Homma, S. Tanda, and T. Nakayama

Appl. Phys. Lett. 61, 1724 (1992); http://dx.doi.org/10.1063/1.108410 (3 pages) | Cited 1 time

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We have performed tunneling experiments on planar junctions Al/AlOx/Nd2−xCexCuO4−y. This is the first experiment using epitaxial films with the planar junction for electron‐doped high Tc Nd2−xCexCuO4−y. The temperature dependencies of the gap features were measured, in which the phonon structures were clearly observed in the normalized conductance curve. These results show accord with the phonon peaks in the phonon density of states obtained recently by neutron inelastic scattering experiments.
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74.50.+r Tunneling phenomena; Josephson effects
74.70.-b Superconducting materials other than cuprates
74.78.-w Superconducting films and low-dimensional structures

Large‐area YBa2Cu3O7−δ thin films on sapphire for microwave applications

B. F. Cole, G.‐C. Liang, N. Newman, K. Char, G. Zaharchuk, and J. S. Martens

Appl. Phys. Lett. 61, 1727 (1992); http://dx.doi.org/10.1063/1.108411 (3 pages) | Cited 50 times

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We have deposited YBa2Cu3O7−δ(YBCO) films with low microwave surface resistance (Rs) on 5‐cm‐diam, oxide‐buffered sapphire substrates by planar magnetron sputtering. MgO buffer layers are used on M‐plane (1010) sapphire, and R‐plane (1102) sapphire is buffered by CeO2. Rs values of 450–620 μΩ at 77 K and 10 GHz were measured across an entire 5‐cm diam YBCO film on M‐plane sapphire. For YBCO on R‐plane sapphire, Rs values at 77 K and 10 GHz were 950 μΩ for a 5‐cm‐diam wafer and 700 μΩ for 1×1 cm2 samples.
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74.70.-b Superconducting materials other than cuprates
81.15.Cd Deposition by sputtering
74.25.N- Response to electromagnetic fields

Influence of 180° domains on ferroelectric properties of BaTiO3 single crystal

Osamu Nakao, Kazuhiko Tomomatsu, Shoji Ajimura, Akihito Kurosaka, and Haruo Tominaga

Appl. Phys. Lett. 61, 1730 (1992); http://dx.doi.org/10.1063/1.108412 (3 pages) | Cited 9 times

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Mechanical poling was applied to a BaTiO3 single crystal grown by the top‐seeded solution growth (TSSG) method to remove its 90° domain walls, and then four‐step electrical poling was applied to rearrange the 180° domain configuration. In each of these steps, the dielectric constant (from 50 kHz to 10 MHz) was measured by using an impedance analyzer, and the 180° domains were observed by the etching method. The dielectric spectra were confirmed to vary with rearrangement in 180° domain configuration. Dielectric constant ϵc in the 〈001〉 direction was 130 at 100 kHz and 58 at 10 MHz. Dielectric constant ϵa in the 〈100〉 direction was 4700 at 100 kHz and 1900 at 10 MHz.
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77.80.Dj Domain structure; hysteresis
77.22.Ch Permittivity (dielectric function)
81.10.Dn Growth from solutions

Low‐gas‐pressure sputtering by means of microwave‐enhanced magnetron plasma excited by electron cyclotron resonance

Yoshikazu Yoshida

Appl. Phys. Lett. 61, 1733 (1992); http://dx.doi.org/10.1063/1.108413 (2 pages) | Cited 5 times

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A sputtering source utilizing both electron cyclotron resonance (ECR) microwave and dc planar magnetron plasmas is described. Microwave power is introduced into the plasma by a coaxial‐type cavity. The magnetron cathode is placed on the open end of the inner conductor. The ECR magnetic field is applied in the open end by magnetron configuration magnets. The microwave propagation from the surface of the plasma column produces additional gas ionization resulting in a denser plasma at constant voltage. The operation pressure of this source is one‐hundredth as low as that of a conventional magnetron source. The deposition rate of Cu is more than 130 nm/min for an argon gas pressure of 8×10−5 Torr, and microwave and dc powers of 500 and 200 W, respectively. Measured deposition uniformity is ±4.5% within a 10 cm diam for a 15‐cm diam target.
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81.15.Cd Deposition by sputtering
52.50.Gj Plasma heating by particle beams
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