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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 727-731 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bulk-quantity Si nanosphere chains have been fabricated. This is accomplished via the spheroidization of Si nanowires of semi-infinite lengths. The process has been extensively investigated by transmission electron microscopy. The nanosphere chains consisted of equally spaced Si crystalline nanospheres connected by Si-oxide bars. The transition from Si nanowires to Si nanosphere chains was determined by the annealing temperature, ambient pressure, initial Si nanowire diameters, and the oxide state of the outer layers of Si nanowires. The relationships between the geometry (size and spacing) of Si nanospheres, the initial state (diameter and oxide state) of Si nanowires, and the experimental conditions are discussed. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6941-6947 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents a numerical simulation of the gas-phase chemistry in diamond deposition processes. The simulation shows that the concentration of the two potential growth species CH3 and C in the boundary layer near the diamond film substrate are sensitive to these species' concentration in the bulk gas. The concentrations in the bulk gas depend, in turn, on the physical arrangement of the reactor, and in particular on the time provided for the gas mixture to reach chemical equilibrium. With sufficient equilibration time, simulations of both a hot-filament reactor and a plasma torch reactors show that the concentration of atomic carbon at the substrate surface can be much higher than the concentration of CH3.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 7981-7983 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon nanowires have been synthesized by laser ablation of Si powder targets at 1200 °C. Transmission electron microscopy study showed that most Si nanowires had smooth surfaces and nearly the same diameter of about 16 nm. Beside the most abundant smooth-surface nanowires, four other forms of nanowires, named spring-shaped, fishbone-shaped, frog-egg-shaped, and necklace-shaped nanowires, were observed. The formation of nanowires into different shapes was explained by the two-step growth model based on the vapor–liquid–solid mechanism. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2185-2187 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a modified method for measuring photorefractive two-wave mixing gain, we presented the experimental demonstration of nonreciprocal energy transfer during two-wave mixing under an external magnetic field. The nonreciprocal energy transfer is observed with mixing gain approaching 164 cm−1 and showed the characteristics of nonlinearity and saturation. A simple model of resonant tunneling and ultrafast carrier lifetime was proposed to explain these results. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 702-704 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a YAG:Nd laser as a pump source, the properties of electroabsorption in Stark geometry AlGaAs/GaAs multiple-quantum-well a photorefractive structure are studied at low temperature. When the temperature decreases from 160 to 120 K, the electroabsorption demonstrates the characteristics of both quenchable and unquenchable components. The quenchable component is interpreted as the photoquenching of EL2, and the unquenchable component is ascribed to the existence of additional deep levels. Modulated with an equivalent circuit, the concentrations of these defects are predicted on the order of 1.3×1016 and 2.2×1018 cm−3, and the capture cross section of additional deep levels is about 4.5×10−16 cm2. The investigation of optical transient current spectra verifies our deduction. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3902-3904 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Si nanowires with uniform size have been synthesized by laser ablation of highly pure Si powder targets mixed with SiO2. A bulk quantity of Si nanowires was successfully obtained by mixing 30%–70% of SiO2 into the Si powder target. SiO2 played a crucial role in enhancing the formation and growth of the Si nanowires. The morphology and microstructure of the Si nanowire tips have been systematically characterized by means of high-resolution transmission electron microscopy. No evidence of metal was found at the tips. The results suggest that Si oxide is more important than metal in catalyzing the formation of Si nanowires. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1835-1837 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon nanowires have been synthesized in high yield and high purity by using a high-temperature laser-ablation method with growth rates ranging from 10 to 80 μm/h. Transmission electron microscopic investigation shows that the nanowires are crystalline Si, and have diameters ranging from 3 to 43 nm and length up to a few hundreds microns. Twins and stacking faults have been observed in the Si core of the nanowires. The lattice structure and constant of the nanowires as determined from x-ray diffraction (XRD) are nearly identical to those of bulk Si, although the relative XRD peak intensities are different from those of randomly oriented Si crystallites. Raman scattering from the nanowires shows an asymmetric peak at the same position as that of bulk crystalline silicon. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1366-1368 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: At a medium substrate temperature of 400 °C and a lower As flux, we have grown an ultrafast AlGaAs/GaAs photorefractive multiple quantum well (MQW) structure by molecular beam epitaxy. The as-grown sample exhibits strong photorefractive effect under the transverse Frantz–Keldysh geometry. A peak electroabsorption of 2100 cm−1 is measured in the as-grown sample in an 11 kV/cm dc electric field, and the peak photorefractive diffraction efficiency can be 1.2%. After postgrowth annealing, the photorefractive effect becomes weak and disappears in samples annealed above 700 °C. Using optical transient current spectroscopy, deep levels are measured in these samples. It is found that deep levels are stable against annealing until 700 °C. Using a pump-probe technique, carrier lifetimes are measured at room temperature. We find that the as-grown sample has a lifetime of 20 ps, while the 700 °C annealed sample has a lifetime of more than 200 ps. The ultrafast lifetime in the as-grown sample is caused by point defects, not by As clusters. Our result show that AlGaAs/GaAs MQW structure grown around 400 °C has better performance of the photorefractive effect. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3824-3826 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We obtained germanium dioxide (GeO2) whiskers in bulk quantity by ablating a germanium target at 820 °C with a pulsed KrF excimer laser in an argon atmosphere. Most of the GeO2 whiskers were smooth and straight with hexagonal or triangular, or quadrilateral cross sections while some of them had a bamboo-shoot-shaped form. Results of scanning electron microscopy, transmission electron microscopy, and x-ray diffraction showed that the whiskers are hexagonal crystalline GeO2. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2921-2923 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By heating a pressed tablet of graphite powder mixed with nickel in a quartz tube mounted inside a high-temperature tube furnace at 1200 °C, amorphous carbon nanowires were formed on the inner wall of the quartz tube near a copper cooling finger. Bright-field images of transmission electron microscopy show that the diameters of the nanowires are around 40 nm. Selected-area electron diffraction and Raman study reveal that the nanowires have an amorphous structure. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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