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Quantum Dot

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Jelena Vuckovic - One of the best experts on this subject based on the ideXlab platform.

  • Fast Quantum Dot single photon source triggered at telecommunications wavelength
    Applied Physics Letters, 2011
    Co-Authors: Kelley Rivoire, Sonia Buckley, Hyochul Kim, Pierre M. Petroff, Arka Majumdar, Jelena Vuckovic
    Abstract:

    We demonstrate a Quantum Dot single photon source at 900 nm triggered at 300 MHz by a continuous wave telecommunications wavelength laser followed by an electro-optic modulator. The Quantum Dot is excited by on-chip-generated second harmonic radiation, resonantly enhanced by a GaAs photonic crystal cavity surrounding the InAs Quantum Dot. Our result suggests a path toward the realization of telecommunications-wavelength-compatible Quantum Dot single photon sources with speeds exceeding 1 GHz.

  • Resonant excitation of a Quantum Dot strongly coupled to a photonic crystal nanocavity
    Physical Review Letters, 2010
    Co-Authors: DIRK ROBERT ENGLUND, Mitsuru Toishi, N. G. Stoltz, Andrei Faraon, Pierre M. Petroff, Arka Majumdar, Jelena Vuckovic
    Abstract:

    We describe the resonant excitation of a single Quantum Dot that is strongly coupled to a photonic crystal nanocavity. The cavity represents a spectral window for resonantly probing the optical transitions of the Quantum Dot. We observe narrow absorption lines attributed to the single and biexcition Quantum Dot transitions and measure antibunched population of the detuned cavity mode [g{(2)}(0)=0.19].

  • Linewidth broadening of a Quantum Dot coupled to an off-resonant cavity
    Physical Review B - Condensed Matter and Materials Physics, 2010
    Co-Authors: Arka Majumdar, Erik D. Kim, Hyochul Kim, Andrei Faraon, Pierre M. Petroff, DIRK ROBERT ENGLUND, Jelena Vuckovic
    Abstract:

    We study the coupling between a photonic crystal cavity and an off-resonant Quantum Dot under resonant excitation of the cavity or the Quantum Dot. Linewidths of the Quantum Dot and the cavity as a function of the excitation laser power are measured. We show that the linewidth of the Quantum Dot, measured by observing the cavity emission, is significantly broadened compared to the theoretical estimate. This indicates additional incoherent coupling between the Quantum Dot and the cavity.

  • Controlling cavity reflectivity with a single Quantum Dot
    Nature, 2007
    Co-Authors: DIRK ROBERT ENGLUND, Ilya Fushman, N. G. Stoltz, Andrei Faraon, Pierre M. Petroff, Jelena Vuckovic
    Abstract:

    Solid-state cavity Quantum electrodynamics (QED) systems offer a robust and scalable platform for Quantum optics experiments and the development of Quantum information processing devices. In particular, systems based on photonic crystal nanocavities and semiconductor Quantum Dots have seen rapid progress. Recent experiments have allowed the observation of weak1 and strong coupling2, 3 regimes of interaction between the photonic crystal cavity and a single Quantum Dot in photoluminescence. In the weak coupling regime1, the Quantum Dot radiative lifetime is modified; in the strong coupling regime3, the coupled Quantum Dot also modifies the cavity spectrum. Several proposals for scalable Quantum information networks and Quantum computation rely on direct probing of the cavity–Quantum Dot coupling, by means of resonant light scattering from strongly or weakly coupled Quantum Dots4, 5, 6, 7, 8, 9. Such experiments have recently been performed in atomic systems10, 11, 12 and superconducting circuit QED systems13, but not in solid-state Quantum Dot–cavity QED systems. Here we present experimental evidence that this interaction can be probed in solid-state systems, and show that, as expected from theory, the Quantum Dot strongly modifies the cavity transmission and reflection spectra. We show that when the Quantum Dot is coupled to the cavity, photons that are resonant with its transition are prohibited from entering the cavity. We observe this effect as the Quantum Dot is tuned through the cavity and the coupling strength between them changes. At high intensity of the probe beam, we observe rapid saturation of the transmission dip. These measurements provide both a method for probing the cavity–Quantum Dot system and a step towards the realization of Quantum devices based on coherent light scattering and large optical nonlinearities from Quantum Dots in photonic crystal cavities.

Pierre M. Petroff - One of the best experts on this subject based on the ideXlab platform.

  • Fast Quantum Dot single photon source triggered at telecommunications wavelength
    Applied Physics Letters, 2011
    Co-Authors: Kelley Rivoire, Sonia Buckley, Hyochul Kim, Pierre M. Petroff, Arka Majumdar, Jelena Vuckovic
    Abstract:

    We demonstrate a Quantum Dot single photon source at 900 nm triggered at 300 MHz by a continuous wave telecommunications wavelength laser followed by an electro-optic modulator. The Quantum Dot is excited by on-chip-generated second harmonic radiation, resonantly enhanced by a GaAs photonic crystal cavity surrounding the InAs Quantum Dot. Our result suggests a path toward the realization of telecommunications-wavelength-compatible Quantum Dot single photon sources with speeds exceeding 1 GHz.

  • Resonant excitation of a Quantum Dot strongly coupled to a photonic crystal nanocavity
    Physical Review Letters, 2010
    Co-Authors: DIRK ROBERT ENGLUND, Mitsuru Toishi, N. G. Stoltz, Andrei Faraon, Pierre M. Petroff, Arka Majumdar, Jelena Vuckovic
    Abstract:

    We describe the resonant excitation of a single Quantum Dot that is strongly coupled to a photonic crystal nanocavity. The cavity represents a spectral window for resonantly probing the optical transitions of the Quantum Dot. We observe narrow absorption lines attributed to the single and biexcition Quantum Dot transitions and measure antibunched population of the detuned cavity mode [g{(2)}(0)=0.19].

  • Linewidth broadening of a Quantum Dot coupled to an off-resonant cavity
    Physical Review B - Condensed Matter and Materials Physics, 2010
    Co-Authors: Arka Majumdar, Erik D. Kim, Hyochul Kim, Andrei Faraon, Pierre M. Petroff, DIRK ROBERT ENGLUND, Jelena Vuckovic
    Abstract:

    We study the coupling between a photonic crystal cavity and an off-resonant Quantum Dot under resonant excitation of the cavity or the Quantum Dot. Linewidths of the Quantum Dot and the cavity as a function of the excitation laser power are measured. We show that the linewidth of the Quantum Dot, measured by observing the cavity emission, is significantly broadened compared to the theoretical estimate. This indicates additional incoherent coupling between the Quantum Dot and the cavity.

  • Controlling cavity reflectivity with a single Quantum Dot
    Nature, 2007
    Co-Authors: DIRK ROBERT ENGLUND, Ilya Fushman, N. G. Stoltz, Andrei Faraon, Pierre M. Petroff, Jelena Vuckovic
    Abstract:

    Solid-state cavity Quantum electrodynamics (QED) systems offer a robust and scalable platform for Quantum optics experiments and the development of Quantum information processing devices. In particular, systems based on photonic crystal nanocavities and semiconductor Quantum Dots have seen rapid progress. Recent experiments have allowed the observation of weak1 and strong coupling2, 3 regimes of interaction between the photonic crystal cavity and a single Quantum Dot in photoluminescence. In the weak coupling regime1, the Quantum Dot radiative lifetime is modified; in the strong coupling regime3, the coupled Quantum Dot also modifies the cavity spectrum. Several proposals for scalable Quantum information networks and Quantum computation rely on direct probing of the cavity–Quantum Dot coupling, by means of resonant light scattering from strongly or weakly coupled Quantum Dots4, 5, 6, 7, 8, 9. Such experiments have recently been performed in atomic systems10, 11, 12 and superconducting circuit QED systems13, but not in solid-state Quantum Dot–cavity QED systems. Here we present experimental evidence that this interaction can be probed in solid-state systems, and show that, as expected from theory, the Quantum Dot strongly modifies the cavity transmission and reflection spectra. We show that when the Quantum Dot is coupled to the cavity, photons that are resonant with its transition are prohibited from entering the cavity. We observe this effect as the Quantum Dot is tuned through the cavity and the coupling strength between them changes. At high intensity of the probe beam, we observe rapid saturation of the transmission dip. These measurements provide both a method for probing the cavity–Quantum Dot system and a step towards the realization of Quantum devices based on coherent light scattering and large optical nonlinearities from Quantum Dots in photonic crystal cavities.

  • Giant optical anisotropy in a single InAs Quantum Dot in a very dilute Quantum-Dot ensemble
    Applied Physics Letters, 2005
    Co-Authors: Ivan Favero, Guillaume Cassabois, Aleksandar Jankovic, Robson Ferreira, David Darson, Christophe Voisin, Claude Delalande, Philippe Roussignol, Antonio Badolato, Pierre M. Petroff
    Abstract:

    We present experimental evidence of giant optical anisotropy in single InAs Quantum Dots. Polarization-resolved photoluminescence spectroscopy reveals a linear polarization ratio with huge fluctuations, from one Quantum Dot to another, in sign and in magnitude with absolute values up to 82%. Systematic measurements on hundreds of Quantum Dots coming from two different laboratories demonstrate that the giant optical anisotropy is an intrinsic feature of dilute Quantum-Dot arrays. (C) 2005 American Institute of Physics.

Byoung Lyong Choi - One of the best experts on this subject based on the ideXlab platform.

  • full colour Quantum Dot displays fabricated by transfer printing
    Nature Photonics, 2011
    Co-Authors: Jungseok Chae, Jang-yeon Kwon, Gehan Amaratunga, Byoung Lyong Choi
    Abstract:

    Scientists describe a size-selective Quantum Dot patterning technique that involves kinetically controlling the nanotransfer process without a solvent. The resulting printed Quantum Dot films exhibit excellent morphology and a well-ordered Quantum Dot structure. This technique allows fabrication of a 4-inch (or larger) thin-film transistor display with high colour purity and extremely high resolution.

  • high performance crosslinked colloidal Quantum Dot light emitting diodes
    Nature Photonics, 2009
    Co-Authors: Eunjoo Jang, Soon-jae Kwon, Byoung Lyong Choi
    Abstract:

    Bright, efficient and low-drive-voltage colloidal Quantum-Dot LEDs that have a crosslinked-polymer Quantum-Dot layer, and use a sol–gel titanium oxide layer for electron transport, are reported. Integrating the QD-LEDs with a silicon thin-film transistor backplane results in a QD-LED display.

  • High-performance crosslinked colloidal Quantum-Dot light-emitting diodes
    Nature Photonics, 2009
    Co-Authors: Kyung Sang Cho, Won Jae Joo, Jai Yong Han, Tae Ho Kim, Sang Jin Lee, Byungki Kim, Eun Kyung Lee, Eunjoo Jang, Soon-jae Kwon, Byoung Lyong Choi
    Abstract:

    Colloidal Quantum-Dot light-emitting diodes have recently received considerable attention due to their ease of colour tunability, high brightness and narrow emission bandwidth. Although there have been rapid advances in luminance, efficiency and lifetime, device performance is still limited by the large energy barriers for hole and electron injection into the Quantum-Dot layer. Here, we show that by crosslinking the colloidal Quantum-Dot layer, the charge injection barrier in a red-light-emitting Quantum-Dot light-emitting diode may be considerably reduced by using a sol–gel TiO2 layer for electron transport. The device architecture is compatible with all-solution device fabrication and the resulting device shows a high luminance (12,380 cd m−2), low turn-on voltage (1.9 V) and high power efficiency (2.41 lm W−1). Incorporation of the technology into a display device with an active matrix drive backplane suggests that the approach has promise for use in high-performance, easy-to-fabricate, large-area displays and illumination sources.

Huiyun Liu - One of the best experts on this subject based on the ideXlab platform.

  • Quantum Dot optoelectronic devices: Lasers, photodetectors and solar cells
    Journal of Physics D: Applied Physics, 2015
    Co-Authors: Jiang Wu, Alwyn Seeds, Siming Chen, Huiyun Liu
    Abstract:

    Nanometre-scale semiconductor devices have been envisioned as next-generation technologies with high integration and functionality. Quantum Dots, or the so-called 'artificial atoms', exhibit unique properties due to their Quantum confinement in all 3D. These unique properties have brought to light the great potential of Quantum Dots in optoelectronic applications. Numerous efforts worldwide have been devoted to these promising nanomaterials for next-generation optoelectronic devices, such as lasers, photodetectors, amplifiers, and solar cells, with the emphasis on improving performance and functionality. Through the development in optoelectronic devices based on Quantum Dots over the last two decades, Quantum Dot devices with exceptional performance surpassing previous devices are evidenced. This review describes recent developments in Quantum Dot optoelectronic devices over the last few years. The paper will highlight the major progress made in 1.3??m Quantum Dot lasers, Quantum Dot infrared photodetectors, and Quantum Dot solar cells.

  • Voltage recovery in charged InAs/GaAs Quantum Dot solar cells
    Nano Energy, 2014
    Co-Authors: Phu Lam, Sabina Hatch, Mingchu Tang, Vitaliy G. Dorogan, Alwyn Seeds, Iñigo Ramiro, Yuriy I. Mazur, Gregory J. Salamo, Jiang Wu, Huiyun Liu
    Abstract:

    The realization of high efficiency Quantum Dot intermediate band solar cells is challenging due to the thermally activated charge escaping at high temperatures. The enhancement in short circuit current of Quantum Dot solar cells is largely undermined by the voltage loss. In this paper, InAs/GaAs Quantum Dot solar cells with direct Si doping in the Quantum Dots are studied. The open circuit voltage is improved with increasing doping concentration in the Quantum Dots. The recovery of open circuit voltage as large as 105. mV is measured. This voltage recovery is attributed to suppressed charge thermal escaping from Quantum Dots. The suppressed thermal coupling is supported by the external Quantum efficiency and photoluminescence measurements. © 2014 The Authors.

Edward H. Sargent - One of the best experts on this subject based on the ideXlab platform.

  • Efficient Luminescence from Perovskite Quantum Dot Solids
    ACS Applied Materials and Interfaces, 2015
    Co-Authors: Younghoon Kim, Emre Yassitepe, Ana F. Nogueira, Xiwen Gong, Pongsakorn Kanjanaboos, Riccardo Comin, Oleksandr Voznyy, Grant Walters, Edward H. Sargent
    Abstract:

    Nanocrystals of CsPbX3 perovskites are promising materials for light-emitting optoelectronics because of their colloidal stability, optically tunable bandgap, bright photoluminescence, and excellent photoluminescence Quantum yield. Despite their promise, nanocrystal-only films of CsPbX3 perovskites have not yet been fabricated; instead, highly insulating polymers have been relied upon to compensate for nanocrystals' unstable surfaces. We develop solution chemistry that enables single-step casting of perovskite nanocrystal films and overcomes problems in both perovskite Quantum Dot purification and film fabrication. Centrifugally cast films retain bright photoluminescence and achieve dense and homogeneous morphologies. The new materials offer a platform for optoelectronic applications of perovskite Quantum Dot solids.

  • Charge-extraction strategies for colloidal Quantum Dot photovoltaics
    Nature Materials, 2014
    Co-Authors: Xinzheng Lan, Silvia Masala, Edward H. Sargent
    Abstract:

    The solar-power conversion efficiencies of colloidal Quantum Dot solar cells have advanced from sub-1% reported in 2005 to a record value of 8.5% in 2013. Much focus has deservedly been placed on densifying, passivating and crosslinking the colloidal Quantum Dot solid. Here we review progress in improving charge extraction, achieved by engineering the composition and structure of the electrode materials that contact the colloidal Quantum Dot film. New classes of structured electrodes have been developed and integrated to form bulk heterojunction devices that enhance photocharge extraction. Control over band offsets, doping and interfacial trap state densities have been essential for achieving improved electrical communication with colloidal Quantum Dot solids. Quantum junction devices that not only tune the optical absorption spectrum, but also provide inherently matched bands across the interface between p- and n-materials, have proven that charge separation can occur efficiently across an all-Quantum-tuned rectifying junction.

  • Colloidal Quantum Dot Optoelectronics and Photovoltaics - Colloidal Quantum Dot optoelectronics and photovoltaics
    2013
    Co-Authors: Gerasimos Konstantatos, Edward H. Sargent
    Abstract:

    1. Engineering colloidal Quantum Dots: synthesis, surface chemistry and self-assembly Maryna I. Bodnarchuk and Maksym Kovalenko 2. Aqueous based colloidal Quantum Dots for optoelectronics Nikolai Gaponik and Vladimir Lesnyak 3. Electronic structure and optical transitions in colloidal semiconductor nanocrystals Todd D. Krauss and Jeffrey J. Peterson 4. Charge and energy transfer in polymer/nanocrystal blends: physics and devices David Ginger and Kevin Noone 5. Multiple exciton generation in semiconductor Quantum Dots and electronically coupled QD arrays for application to third generation photovoltaic solar cells M. C. Beard, J. M. Luther and A. J. Nozik 6. Colloidal Quantum Dot light emitting diodes Vanessa Wood, Matt Panzer, Seth-Coe Sullivan and Vladimir Bulovic 7. Optical gain and lasing in colloidal Quantum Dots Sjoerd Hoogland 8. Solution-processed Quantum Dot photodetectors Gerasimos Konstantatos 9. Solution processed infrared Quantum Dot solar cells Jiang Tang and Edward Sargent 10. Heterojunction solar cells based on colloidal Quantum Dots Delia J. Milliron and Jeffrey J. Urban 11. Semiconductor sensitized TiO2 mesoporous solar cells Etgar Lioz, Hyo Joong Lee, Sang Il Seok, Md. K. Nazeeruddin and Michael Graetzel.

  • Colloidal Quantum Dot photovoltaics: The effect of polydispersity
    Nano Letters, 2012
    Co-Authors: David Zhitomirsky, Illan J. Kramer, André J. Labelle, Ratan Debnath, Jun Pan, Armin Fischer, Osman M. Bakr, Edward H. Sargent
    Abstract:

    The size-effect tunability of colloidal Quantum Dots enables facile engineering of the bandgap at the time of nanoparticle synthesis. The dependence of effective bandgap on nanoparticle size also presents a challenge if the size dispersion, hence bandgap variability, is not well-controlled within a given Quantum Dot solid. The impact of this polydispersity is well-studied in luminescent devices as well as in unipolar electronic transport; however, the requirements on monodispersity have yet to be quantified in photovoltaics. Here we carry out a series of combined experimental and model-based studies aimed at clarifying, and quantifying, the importance of Quantum Dot monodispersity in photovoltaics. We successfully predict, using a simple model, the dependence of both open-circuit voltage and photoluminescence behavior on the density of small-bandgap (large-diameter) Quantum Dot inclusions. The model requires inclusion of trap states to explain the experimental data quantitatively. We then explore using this same experimentally tested model the implications of a broadened Quantum Dot population on device performance. We report that present-day colloidal Quantum Dot photovoltaic devices with typical inhomogeneous linewidths of 100-150 meV are dominated by surface traps, and it is for this reason that they see marginal benefit from reduction in polydispersity. Upon eliminating surface traps, achieving inhomogeneous broadening of 50 meV or less will lead to device performance that sees very little deleterious impact from polydispersity.