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  • 1
    Electronic Resource
    Electronic Resource
    Void-like defects in annealed Czochralski silicon (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2311-2312 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Void-like defects of octahedron structure having {111} facets were observed in annealed Czochralski silicon. The amorphous coverage of SiOx and SiCx on the inner surface of the defects was identified using transmission electron microscopy and electron energy-loss spectroscopy. It is suggested that these defects are a kind of amorphous precipitate origin. A mechanism for the generation of these defects and the previously reported solid amorphous precipitates is proposed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121807
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  • 2
    Electronic Resource
    Electronic Resource
    Accurate measurement of phase shift in electron holography (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 771-773 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method is proposed for the accurate measurement of phase shift in electron holography. The method is based on the use of moiré fringes resulting from the subtraction of a null electron hologram by a real object hologram recorded under slightly different experimental conditions. This method does not require any optical or digital reconstruction of the electron hologram, and is shown to be highly sensitive to the phase shift of the electron wave passing through an object. Using experimental results obtained from a single particle of silicon, we demonstrate that the sensitivity of this method to phase shift may easily be amplified by more than 11 times compared with the conventional method using an ordinary electron hologram. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120888
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  • 3
    Electronic Resource
    Electronic Resource
    Integration of n-type and p-type quantum-well infrared photodetectors for sequential multicolor operation (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2067-2069 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A multicolor infrared photodetector based on the epitaxial integration of an n-type with a p-type GaAs/AlGaAs quantum-well stack is experimentally demonstrated. Additionally, a quantum-well GaAs light-emitting diode is inserted between the stacks to achieve up-conversion of mid-infrared radiation to near-infrared signal. This device shows a remarkable selectivity on wavelength: depending on the bias voltage the peak wavelength detection can be switched on and off between 9.1 and 4.85 μm. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1359482
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  • 4
    Electronic Resource
    Electronic Resource
    Quantum dot infrared photodetectors (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 79-81 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Self-assembled strained semiconductor nanostructures have been grown on GaAs substrates to fabricate quantum dot infrared photodetectors. State-filling photoluminescence experiments have been used to probe the zero-dimensional states and revealed four atomic-like shells (s,p,d,f) with an excitonic intersublevel energy spacing which was adjusted to ∼60 meV. The lower electronic shells were populated with carriers by n doping the heterostructure, and transitions from the occupied quantum dot states to the wetting layer or to the continuum states resulted in infrared photodetection. We demonstrate broadband normal-incidence detection with a responsivity of a few hundred mA/W at a detection wavelength of ∼5 μm. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1337649
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  • 5
    Electronic Resource
    Electronic Resource
    Resonant-cavity-enhanced p-type GaAs/AlGaAs quantum-well infrared photodetectors (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2400-2402 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Resonant cavities are used to enhance the absorption efficiency in p-type GaAs/AlGaAs quantum-well infrared photodetectors. The cavities are fabricated by applying thick gold films on the detector bottom sides after substrate removal via selective wet etching. The observed peak enhancement and spectral shape are in good agreement with model predictions. Peak absorption of about 25% is obtained for the device studied. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1317548
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  • 6
    Electronic Resource
    Electronic Resource
    GaAs/AlGaAs quantum-well photodetector for visible and middle infrared dual-band detection (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2437-2439 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present experimental results on quantum-well photodetectors for visible and infrared dual-band detection. Large band gap top contacts were used on a standard GaAs/AlGaAs quantum-well infrared photodetector so that visible light could reach the quantum-well region and be absorbed via interband transitions. Two designs were investigated, using a high Al fraction AlGaAs and a short period GaAs/AlAs superlattice contact layer. The dual-band response spectral regions are 0.55–0.7 and 7–10 μm. Measured responsivities are about 0.7 A/W at 8.3 μm and 0.1 A/W at 0.63 μm under −6 V bias voltage. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1318232
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of Mutagenic Treatments on Somaclonal Variation in Wheat (Triticum aestivum L.) (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 105 (1990), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Different wheat genotypes were treated with gamma-rays, sodium azide (SA) and EMS before tissue culture and immature embryos from M1 plants or plants shortly after exposure to gamma-rays were used to initiate callus culture. Thousands of plants were regenerated and used to investigate the effect of mutagenic treatments on the regenerated plants and somaclonal variation in the M3R2 and M2R2 generations. The results showed that mutagen-induced damage in terms of reduction in plant height, fertility and spike length were not outstanding in the regenerated plants as compared with the untreated control. In the M3R2 generation, only SA treatment had significantly higher frequencies of somaclonal variations than the control. Increases in the variation frequencies were observed when explant embryos were irradiated with 2.5 and 5 gy gamma-rays and the highest frequency appeared when embryos were exposed to 5 gy gamma-rays on the 5th day after anthesis. Increased variation spectra also resulted from mutagenic treatments and most of the variants recovered were unsuitable for plant improvement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1990.tb00451.x
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  • 8
    Electronic Resource
    Electronic Resource
    Formation dynamics of layer-by-layer self-assembled films probed by second harmonic generation (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 3956-3960 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the formation dynamics of self-assembled polyelectrolyte multilayers on glass substrates by in situ and ex situ second harmonic generation (SHG) measurements and atomic force microscopy (AFM). The time dependence of the SHG signal during the adsorption process is attributed to a time dependent surface potential of the polyelectrolyte film. The dynamics can be quantitatively understood using a random sequential adsorption (RSA) model for the buildup of a film consisting of polyelectrolyte disks with polydisperse sizes. Differences between wet and dry films are also investigated. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1495839
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  • 9
    Electronic Resource
    Electronic Resource
    In Vitro Culture of Hybrid Indica Rice Combined with Mutagenesis (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 108 (1992), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The mutagenic effects of gamma radiation and sodium azide (SA) immersion of explants on culturability and frequency of somaclonal variation in indica rice were investigated. The results showed that young inflorescence and mature embryo were satisfactory explants both for in vitro culture and for mutagenesis. 1 kR gamma rays applied to immature embryos and exposure of calli derived from mature seeds at the dose range of 250—500 R led to a higher rate of callusing and plantlet regeneration, 0.5—1 kR would be the appropriate exposure for young inflorescence to produce a better culture response and higher variability, and 2.5—5.0 kR the optimal dose range for mature embryos. Immersion of mature seed in 2—4 mM sodium azide solution is a concentration level to induce these effects in indica rice. Application of optimal gamma exposure and chemical mutagen to rice explants enhanced the somaclonal variation frequency and provided a large number of variants useful for rice breeding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1992.tb00108.x
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  • 10
    Electronic Resource
    Electronic Resource
    STEP – a trial-and-error procedure for crystal structure determination. I. A description of the program system SYSTEM90 (1994)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 50 (1994), S. 748-753 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: This paper describes a new trial-and-error direct-methods procedure called STEP. A set of strong reflections, sufficient to solve the structure, is divided into a hierarchy of smaller soluble and connected subsystems. Within each subsystem, the reflections are required to be well connected with each other, given that the phases of all reflections in the previous subsystems are known. A trial-and-error procedure is then employed to provide an approximate solution to an overdetermined set of equations. Subsequently, phases are refined by one of two available tangent formulae and then assessed for plausibility by figures of merit. A new overall figure of merit, XDFOM, has been found to be very effective in picking up a correct solution and the procedure is stopped when XDFOM exceeds 4.0. STEP is incorporated in a package called SYSTEM90, which has been tested with four difficult known structures and one difficult unknown structure. In all cases, a correct phase set was found. SYSTEM90 is indicated as a powerful technique for the solution of difficult and large structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767394004460
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