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  • 1
    Electronic Resource
    Electronic Resource
    Resonant excitation of intraband absorption in InAs/GaAs self-assembled quantum dots (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4356-4362 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the infrared absorption between confined levels in the conduction and valence bands of undoped InAs/GaAs self-assembled quantum dots. The intraband absorption, which is measured by photoinduced spectroscopy, is analyzed under resonant and nonresonant optical excitation of the quantum dots. The assignment of electron and hole intraband transitions is achieved on the basis of experimental results obtained with n-and p-doped quantum dots. A careful analysis of the absorption spectra shows that several hole transitions and one electron transition with a large broadening are evidenced in the mid-infrared spectral range. We show that the amplitude of the intraband absorption depends on the pump excitation wavelength and exhibits a maximum when the dots are populated via the wetting layer. The spectral shape of the hole intraband absorption is very weakly dependent on the excitation wavelength. The amplitude of the photoinduced hole intraband absorption exhibits a sublinear behavior with the pump intensity. This feature is explained by the state filling of the quantum dots. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368655
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  • 2
    Electronic Resource
    Electronic Resource
    Silicon–on–insulator waveguide photodetector with Ge/Si self-assembled islands (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 1858-1861 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated a silicon-based near-infrared photodetector using a waveguide with strong optical confinement. The high-difference index waveguide is obtained with a silicon–on–insulator substrate. The optically active region consists of self-assembled Ge/Si islands embedded in a p-i-n junction. The Ge/Si islands grown by high-pressure chemical-vapor deposition exhibit a broad photoluminescence and electroluminescence which are resonant around 1.5 μm. The photoluminescence and electroluminescence energies are correlated to the island size and to the island composition using a six-band k⋅p calculation. The spectral responsivity of the detectors is measured in a front facet coupling geometry with a broadband source and with semiconductor laser diodes. For a 0 V applied bias, responsivities of 25 and 0.25 mA/W are measured at room temperature at 1.3 and 1.55 μm, respectively. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1493656
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  • 3
    Electronic Resource
    Electronic Resource
    Intraband absorption in Ge/Si self-assembled quantum dots (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 401-403 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed intraband absorption in Ge/Si self-assembled quantum dots. The self-assembled quantum dots are grown at 550 °C by chemical vapor deposition. Atomic force microscopy shows that the quantum dots have a square-based pyramidal shape ((approximate)100 nm base length) and a density (approximate)2×109 cm−2. Intraband absorption in the valence band is observed around 300 meV (4.2 μm wavelength) using a photoinduced spectroscopy technique. The intraband absorption is in-plane polarized. It is attributed to bound-to-continuum transitions since the intraband energy corresponds to the energy difference between the Si band gap and the photoluminescence energy of the quantum dots. The magnitude of the intraband absorption saturates when the ground level of the quantum dots is filled. This feature allows the measurement of the in-plane absorption cross section of the intraband transition which is found as large as 2×10−13 cm2. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123083
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  • 4
    Electronic Resource
    Electronic Resource
    Near-infrared waveguide photodetector with Ge/Si self-assembled quantum dots (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 509-511 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated near-infrared p-i-n photodetectors with Ge/Si self-assembled quantum dots. The self-assembled quantum dots were grown by chemical vapor deposition on Si(001). A vertical stacking of 20 layers of quantum dots was inserted into a near-infrared waveguide obtained with a Si0.98Ge0.02 alloy. The samples were processed into ridge waveguides. The photoresponse of the device covers the near-infrared spectral range up to 1.5 μm. At room temperature, a responsivity of 210 mA/W is measured at 1.3 μm and 3 mA/W at 1.5 μm. The photocurrent is compared to the photoluminescence and to the absorption of the quantum dots measured in the waveguide geometry. At room temperature, the onset of the absorption is around 1.9 μm (0.65 eV). The photocurrent is blueshifted as compared to the absorption. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1435063
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  • 5
    Electronic Resource
    Electronic Resource
    Enhancement of second-harmonic generation in a one-dimensional semiconductor photonic band gap (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3021-3023 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate significant enhancement of second-order nonlinear interactions in a one-dimensional semiconductor Bragg mirror operating as a photonic band gap structure. The enhancement comes from a simultaneous availability of a high density of states, thanks to high field localization, and the improvement of effective coherent length near the photonic band edge. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1372356
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  • 6
    Electronic Resource
    Electronic Resource
    Midinfrared absorption and photocurrent spectroscopy of InAs/GaAs self-assembled quantum dots (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2327-2329 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a comparison between the midinfrared absorption and the photocurrent response of n-doped InAs/GaAs self-assembled quantum dots. The absorption, resonant at 160 meV, is polarized along the z growth axis of the dots. The photocurrent is dominated by a z-polarized resonance around 220 meV (5.6 μm wavelength). A weaker component of the photocurrent is observed for an in-plane polarized excitation. The photoresponse can be measured for a 0 V applied bias. The photoresponsivity is investigated as a function of the applied bias. The responsivity and the dark current exhibit an asymmetric profile versus the external bias. This asymmetry is correlated to the structural asymmetry of the quantum dot layers. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1365411
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  • 7
    Electronic Resource
    Electronic Resource
    Electroluminescence of Ge/Si self-assembled quantum dots grown by chemical vapor deposition (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1822-1824 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated light-emitting diodes on Si operating in the near-infrared. The active region of the p–i–n diodes consists of Ge/Si self-assembled quantum dots. The Ge islands were grown in an industrial 200 mm single-wafer chemical vapor deposition reactor. The photoluminescence and the electroluminescence of the islands are resonant in the spectral range around 1.4–1.5 μm wavelength. The electroluminescence is observed up to room temperature. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1308526
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  • 8
    Electronic Resource
    Electronic Resource
    Midinfrared second-harmonic generation in p-type InAs/GaAs self-assembled quantum dots (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 835-837 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Resonant second-harmonic generation is reported in InAs/GaAs self-assembled quantum dots. Frequency doubling is observed between confined states in the valence band of the quantum dots. The second-order nonlinear susceptibility is maximum at 168 meV (7.4 μm wavelength) and is observed for an in-plane polarized excitation. A value of χzxx(2) as large as 2×10−7 (m/V) is measured for one dot plane. A three-dimensional numerical calculation of the valence band states shows that the second-harmonic generation involves a resonant excitation between the h000 and h101 states and a state close to the continuum wetting layer states. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124529
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  • 9
    Electronic Resource
    Electronic Resource
    Saturation of intraband absorption and electron relaxation time in n-doped InAs/GaAs self-assembled quantum dots (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3818-3821 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed the saturation of intraband absorption in InAs/GaAs self-assembled quantum dots. The investigated n-doped self-assembled quantum dots exhibit an intraband absorption within the conduction band, which is peaked at an 8 μm wavelength. The saturation of the intraband absorption is achieved with an infrared pump delivered by a pulsed free-electron laser. The saturation of the transition is observed for an intensity around (approximate)0.6 MW cm−2. The electron relaxation time under intraband excitation is measured by time-resolved pump–probe experiments. An electron relaxation time T1(approximate)3 ps is reported. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122904
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  • 10
    Electronic Resource
    Electronic Resource
    Intersubband stimulated emission in GaAs/AlGaAs quantum wells: Pump-probe experiments using a two-color free-electron laser (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 3197-3199 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intersubband stimulated emission under optical pumping has been observed in the conduction band of GaAs–AlGaAs quantum wells. The asymmetric coupled quantum wells which exhibit three conduction bound levels are designed to exhibit population inversion under optical pumping. An optical excitation at λ=9.2 μm is used to bleach the absorption between the ground and second excited subband. The population inversion between excited subbands is pumped and probed on a picosecond time scale by a tunable two-color free-electron laser. The stimulated amplification is studied at low temperature in infrared waveguides as a function of the waveguide length and of the probe wavelength. A stimulated gain (approximate)80 cm−1 is measured at 12.5 μm in agreement with calculations. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119125
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