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14 Aug 1989

Volume 55, Issue 7, pp. 607-704

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Strain‐induced confinement of carriers to quantum wires and dots within an InGaAs‐InP quantum well

K. Kash, R. Bhat, Derek D. Mahoney, P. S. D. Lin, A. Scherer, J. M. Worlock, B. P. Van der Gaag, M. Koza, and P. Grabbe

Appl. Phys. Lett. 55, 681 (1989); http://dx.doi.org/10.1063/1.102266 (3 pages) | Cited 56 times

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We describe a novel method of confining carriers by deliberately creating large inhomogeneous strain patterns in a quantum well. The strain modulates the band gap to provide lateral quantum confinement for excitons. Here, we generate strain confinement in an InGaAs quantum well by reactive ion beam assisted etching through an overlying compressed pseudomorphic quaternary layer using etch masks patterned by electron beam lithography. Photoluminescence spectra of arrays of wires and dots show red‐shifted band gaps in direct evidence of lateral confinement. We compare our results to finite element calculations of the inhomogeneous strain in an InP substrate from a compressed overlayer patterned into rectangular wires.
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81.65.-b Surface treatments
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

Hydrogenation of molecular beam epitaxial Ge0.36Si0.64 on Si

Y. H. Xie, H. S. Luftman, J. Lopata, and J. C. Bean

Appl. Phys. Lett. 55, 684 (1989); http://dx.doi.org/10.1063/1.101821 (3 pages) | Cited 1 time

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Passivation of threading dislocations in an incommensurate Ge0.36Si0.64/Si structure is studied using hydrogen plasma anneal. The reverse current of pn junction diodes made of the above structure is reduced by more than 30 times after hydrogenation. Associated improvements in the current‐voltage (I‐V) characteristics is also observed. Capacitance‐voltage (C‐V) measurements reveal that the shallow dopants neutralized by hydrogenation reactivate at lower temperatures than the passivated deep level defects. Secondary‐ion mass spectroscopy (SIMS) analysis established the depth of diffusion of hydrogen under the experimental conditions. Work in this direction could eventually lead to the integration of infrared detectors with Si very large scale integration (VLSI).
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.Kk Junction diodes
81.40.Rs Electrical and magnetic properties related to treatment conditions
81.65.-b Surface treatments

Carbon diffusion in undoped, n‐type, and p‐type GaAs

B. T. Cunningham, L. J. Guido, J. E. Baker, J. S. Major, N. Holonyak, and G. E. Stillman

Appl. Phys. Lett. 55, 687 (1989); http://dx.doi.org/10.1063/1.101822 (3 pages) | Cited 99 times

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The effects of background doping, surface encapsulation, and As4 overpressure on carbon diffusion have been studied by annealing samples with 1000 Å p‐type carbon doping spikes grown within 1 μm layers of undoped (n−), Se‐doped (n+), and Mg‐doped (p+) GaAs. The layers were grown by low‐pressure metalorganic chemical vapor deposition using CCl4 as the carbon doping source. Two different As4 overpressure conditions were investigated: (1) the equilibrium pAs4 over GaAs (no excess As), and (2) pAs4 ∼2.5 atm. For each As4 overpressure condition, both capless and Si3N4‐capped samples of the n−‐, n+‐, and p+‐GaAs crystals were annealed simultaneously (825 °C, 24 h). Secondary‐ion mass spectroscopy was used to measure the atomic carbon depth profiles. The carbon diffusion coefficient is always low, but depends on the background doping, being highest in Mg‐doped (p+) GaAs and lowest in Se‐doped (n+) GaAs. The influence of surface encapsulation (Si3N4) and pAs4 on carbon diffusion is minimal.
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66.30.J- Diffusion of impurities
68.35.Fx Diffusion; interface formation
68.35.Dv Composition, segregation; defects and impurities

X‐ray diffraction from ordered regions in GaInP ternary alloys

Hiroshi Okuda, Chikashi Anayama, Satoyasu Narita, Makoto Kondo, Toshiyuki Tanahashi, Osamu Ueda, and Kazuo Nakajima

Appl. Phys. Lett. 55, 690 (1989); http://dx.doi.org/10.1063/1.101823 (2 pages) | Cited 5 times

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Ordered structure in GaInP alloys grown on (001) GaAs substrates by low‐pressure metalorganic vapor phase epitaxy has been investigated by means of x‐ray diffraction and transmission electron microscopy. We found a broad peak of CuPt I type (111)B ordering in the x‐ray measurements. X‐ray results gave the total amount of ordered region and the average size of each ordered domain. Room‐temperature photoluminescence peak energy anomalies were found to be related to the amount of the order phase.
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68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification
61.05.C- X-ray diffraction and scattering
61.66.Fn Inorganic compounds

Properties of ultrahigh vacuum self‐implantation‐induced amorphous germanium

G. Peto, J. Kanski, and G. Holmen

Appl. Phys. Lett. 55, 692 (1989); http://dx.doi.org/10.1063/1.101824 (2 pages) | Cited 2 times

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Ge (111) was self‐implanted in ultrahigh vacuum to prepare an impurity‐free amorphous layer. The same extraordinary amorphous state of Ge was induced as that found earlier with 121Sb+ implantation in normal vacuum. This eliminates the possibility that this anomalous a‐Ge is impurity stabilized.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification
61.80.Jh Ion radiation effects

Resonant tunneling of holes in AlSb/GaSb/AlSb double‐barrier heterostructures

R. Beresford, L. F. Luo, and W. I. Wang

Appl. Phys. Lett. 55, 694 (1989); http://dx.doi.org/10.1063/1.101801 (2 pages) | Cited 13 times

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We have made the first observations of resonant tunneling in the AlSb/GaSb material system. Double‐barrier p‐type heterostructures exhibit two distinct features in their current‐voltage characteristics, indicating resonant tunneling via confined valence‐band states. The measured energy level positions are consistent with a substantial valence‐band offset of approximately 0.4 eV.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Characteristics and growth of single crystals of Y1Ba2Cu3O7 with superior microwave properties

Dong‐Ho Wu, W. L. Kennedy, C. Zahopoulos, and S. Sridhar

Appl. Phys. Lett. 55, 696 (1989); http://dx.doi.org/10.1063/1.102440 (3 pages) | Cited 17 times

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We report the fabrication and high‐frequency characterization of single crystals of Y1Ba2Cu3O7 with extremely sharp microwave transitions. The 10 GHz surface resistance Rs is less than 400 μΩ, at temperatures 4 K below the transition temperature. The electrodynamic characteristics of these crystals were examined via several measurements, and we demonstrate that high quality crystals which show very low Rs also possess small penetration depths λ(0)=1600 Å and small magnetic field effects on the penetration depth characterized by k(0)≡(dλ/dB2)T→0=10−3 Å/G2. In polycrystals, and even in poor single crystals, the presence of Josephson junctions of typical effective area ∼4 μm2 leads to poor microwave properties, with electrodynamic parameters orders of magnitude larger.
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74.70.-b Superconducting materials other than cuprates
74.50.+r Tunneling phenomena; Josephson effects
74.25.N- Response to electromagnetic fields
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Origin of enhanced growth of the 110 K superconducting phase by Pb doping in the Bi‐Sr‐Ca‐Cu‐O system

Donglu Shi, Mark S. Boley, J. G. Chen, Ming Xu, K. Vandervoort, Y. X. Liao, A. Zangvil, Justin Akujieze, and Carlo Segre

Appl. Phys. Lett. 55, 699 (1989); http://dx.doi.org/10.1063/1.101573 (3 pages) | Cited 34 times

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Kinetics of the 110 K superconducting phase formation has been studied in the Bi‐Sr‐Ca‐Cu‐O system with and without the addition of small amounts of lead. The kinetics of the phase transformation has been greatly affected by lead doping. The time required for the maximum formation of the 110 K phase is substantially reduced by the addition of lead. This phenomenon has been shown to be associated with the lead enhancing the nucleation and growth process of the 110 K phase and the diffusivity of calcium and copper.
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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
66.30.-h Diffusion in solids
64.70.K- Solid-solid transitions

As‐grown superconducting Bi‐Sr‐Ca‐Cu‐O thin films by coevaporation

T. Satoh, T. Yoshitake, S. Miura, J. Fujita, Y. Kubo, and H. Igarashi

Appl. Phys. Lett. 55, 702 (1989); http://dx.doi.org/10.1063/1.101574 (3 pages) | Cited 14 times

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Superconducting Bi‐Sr‐Ca‐Cu‐O thin films have been prepared on (100) MgO substrates at about 600 °C by coevaporation. The c‐axis lattice constant of this system was controlled to the values of 24–43 Å by changing film composition. Superconducting transition temperatures of these films were affected by substrate temperature and by a post‐deposition annealing at a low temperature. The highest zero resistance temperature (Tc, zero) of the as‐grown Bi2(Sr,Ca)3Cu2Ox film was 79 K. The best Bi2(Sr, Ca)4Cu3Ox film showed an onset temperature of 105 K and Tc, zero zero of 78 K after annealing at 400 °C for 1 h.
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74.78.-w Superconducting films and low-dimensional structures
68.55.-a Thin film structure and morphology
74.70.-b Superconducting materials other than cuprates
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
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