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  • 1
    Electronic Resource
    Electronic Resource
    Quantum box size effect on vertical self-alignment studied using cross-sectional scanning tunneling microscopy (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2608-2610 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InAs quantum boxes separated by GaAs spacer layers are known to exhibit a vertical self-organization along the growth direction. The alignment probability between two sets of quantum boxes depends strongly on the spacer layer thickness Zs. In this letter, we study samples containing multiple arrays of quantum boxes separated by GaAs spacer layers of various thicknesses, using cross-sectional scanning tunneling microscopy. This work experimentally evidences that the spacer layer characteristic thickness Zs0 below which a vertical self-alignment occurs, depends on the size of the quantum boxes. These results are interpreted using a theoretical two-dimensional model. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123912
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  • 2
    Electronic Resource
    Electronic Resource
    Scanning tunneling microscopy and scanning tunneling spectroscopy of self-assembled InAs quantum dots (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 96-98 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present cross-sectional scanning tunneling microscopy images and scanning tunneling spectroscopy results of InAs quantum dots grown on GaAs. The samples contain 12 arrays of quantum dots. The analysis of the scanning tunneling microscope images reveals the self-alignment of the dots as well as the different dot interfaces with the under- and overgrown GaAs layers. We measure the strain distribution along the [001] direction in the (110) plane. The roughness of the dot interfaces along the [1¯10] direction is also estimated and local spectroscopy of the dots evidences the electronic confinement (measured gap of 1.25 eV compared with 0.4 eV for bulk InAs). © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121792
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  • 3
    Electronic Resource
    Electronic Resource
    Oriented Sm2(Co, Cu, Fe, Zr)17 permanent magnets produced by solidification in a magnetic field (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 4843-4847 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Oriented samples of Sm2(Co, Cu, Fe, Zr)17 have been produced by solidification from the liquid state in the presence of a magnetic field of several Tesla, their easy magnetization axis being in the direction of the applied magnetic field. This orientation allowed the development of a new process to produce anisotropic permanent magnets without using the metallurgical powder technology. This is the case for the samarium–cobalt magnets presented in this paper. In particular, it is shown that the chemical composition used to produce them might be adapted from those used for sintered Sm2(Co, Cu, Fe, Zr)17 magnets, in order to optimize their magnetic properties. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367281
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  • 4
    Electronic Resource
    Electronic Resource
    Thermally assisted formation of silicon islands on a silicon-on-insulator substrate (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 106-111 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the self-formation of nanometer-size silicon islands on a silicon-on-insulator (SOI) substrate that is associated with simple thermal treatment in the range of 500–900 °C. We study the island formation process versus the temperature of the thermal annealing, the thickness of the top silicon layer, and the presence of a native oxide on this top layer. The island size distribution is also studied. To follow the chemical evolution of the top layer, we used in situ Auger electron spectroscopy in an ultrahigh vacuum chamber. The island morphology is studied using ex situ atomic force microscopy (AFM). The formation temperature increases with the thickness of the top silicon layer and can be explained by thermal stress induced at the Si/SiO2 interface. From a technological point of view, this study shows the limitation of a SOI substrate with a thin silicon top layer under thermal treatment. On the other hand, it opens up an easy way in which to build silicon dots on an insulator. Finally, we present preliminary data that show the possibility of charging these nanocrystallites with an AFM tip. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1420761
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  • 5
    Electronic Resource
    Electronic Resource
    Nanoscale desorption of H-passivated Si(100)–2×1 surfaces using an ultrahigh vacuum scanning tunneling microscope (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 3887-3892 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nanoscale desorption of the Si(100)–2×1 hydrogen terminated surface has been achieved using a scanning tunneling microscope (STM) in an ultrahigh vacuum chamber. We have studied the patterned linewidth as a function of the sample bias and the dose, either with the feedback servo loop on or off. We propose a simple analytical model to explain the variation of the linewidth versus the electron dose. Finally, we show that the best resolution is obtained for pulsed voltages with the STM feedback servo loop on. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369760
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  • 6
    Electronic Resource
    Electronic Resource
    Nanooxidation of silicon with an atomic force microscope: A pulsed voltage technique (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 4049-4051 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The use of an atomic force microscope (AFM) as an active tool to realize silicon nanolithography is now well known, using a continuous voltage applied between the AFM tip and the surface. The main drawback of this technique is the poor reliability of the tip due to the strong tip-surface interaction. An original way which both increases the reliability and improves the nanolithography resolution is the use of pulsed voltages instead of continuous polarization. In such a case, the interaction time of the tip with the surface under electric field decreases. The frequency oscillation (in noncontact mode) of the cantilever is taken as a reference, and pulsed voltages with variable phase and duty cycle are used. We show that the variation of the phase allows a 100% modulation of the oxide width. Finally, combining this lithography technique with wet etching, a 17.5 nm wide and 5.5 nm height nanowire has been obtained starting from a silicon-on-insulator substrate. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123257
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  • 7
    Electronic Resource
    Electronic Resource
    Optical study of GaAs/AlAs pillar microcavities with elliptical cross section (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1421-1423 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs/AlAs pillar microcavities with elliptical cross section have been fabricated by molecular beam epitaxy, electron-beam lithography, and reactive ion etching. We study their lowest energy confined photonic modes by photoluminescence, using a quantum box array placed inside the cavity as an internal broadband light source. Such an anisotropic cross section allows to split the twofold polarization degenerate fundamental mode of circular micropillars into a pair of orthogonal linearly polarized modes. Their energy splitting, which is well accounted for by a simple perturbative model, is studied experimentally and theoretically as a function of the eccentricity and average radius of the pillars. Splittings as large as 15 meV are observed, which is very encouraging for applications ranging from the improvement of the polarization locking in vertical cavity lasers to the fabrication of light emitting diodes with a better control of the spontaneous emission. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120582
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  • 8
    Electronic Resource
    Electronic Resource
    Optical losses in plasma-etched AlGaAs microresonators using reflection spectroscopy (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 911-913 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical losses in dry-etched monolithic microresonators have been studied as a function of their lateral dimensions. Cylindrical microresonators with various radii have been etched from a planar GaAlAs/GaAs microcavity with a very high quality factor (Q≅11 700). Measurements of the resonance linewidth, using Ti-sapphire laser spectroscopy allowed to study the degradation of the Q factor at small radii. The Q factor is four times smaller in 1.1 μm radius microresonators, compared to the unprocessed cavity. This degradation is attributed to optical scattering from sidewalls, whose efficiency is shown to scale with the guided mode intensity at the microresonator edge. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123407
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  • 9
    Electronic Resource
    Electronic Resource
    Formation of silicon islands on a silicon on insulator substrate upon thermal annealing (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3271-3273 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Starting from silicon on insulator substrates, we show that a thermal treatment (in the 600–900 °C range) induces the creation of silicon islands. To characterize the island formation as well as the initial silicon layer thickness, we use in situ Auger electron spectroscopy analysis in an ultrahigh vacuum chamber. The island size and density are studied with an ex situ atomic force microscope. We show that the formation temperature of the islands increases from 575 to 875 °C as the initial silicon layer thickness increases from 1 to 19 nm. For the 1 nm thickness, the minimum island size is reached (semispherical shape with a 16 nm diameter). The phenomena involved in the island formation are discussed and the study of the variations of the calculated stress tensor (IMPACT software) as a function of the thermal treatment explain the behavior of the top silicon layer. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126603
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  • 10
    Electronic Resource
    Electronic Resource
    Atomic force microscope tip-surface behavior under continuous bias or pulsed voltages in noncontact mode (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1018-1020 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The atomic force microscope is now widely used to oxidize a silicon surface with a continuous bias or pulsed voltages applied between the tip and the silicon surface. The aim of this letter is to study the induced electrostatic effect on the cantilever oscillation in noncontact mode when pulsed voltages are used for nanooxidation. Depending on the relative amplitudes between electrostatic and mechanical excitations, and also on the phase between the pulsed voltages and the mechanical excitation, the cantilever response can dramatically vary. We focus on the details of controlling the feedback loop and exposure conditions in noncontact mode. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125925
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