The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Lincoln J Lauhon - One of the best experts on this subject based on the ideXlab platform.
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elucidating the photoresponse of ultrathin mos2 field effect transistors by scanning Photocurrent microscopy
Journal of Physical Chemistry Letters, 2013Co-Authors: Deep Jariwala, Vinod K Sangwan, Tobin J Marks, Mark C Hersam, Lincoln J LauhonAbstract:The mechanisms underlying the intrinsic photoresponse of few-layer (FL) molybdenum disulfide (MoS2) field-effect transistors are investigated via scanning Photocurrent microscopy. We attribute the locally enhanced Photocurrent to band-bending-assisted separation of photoexcited carriers at the MoS2/Au interface. The wavelength-dependent Photocurrents of FL MoS2 transistors qualitatively follow the optical absorption spectra of MoS2, providing direct evidence of interband photoexcitation. Time and spectrally resolved Photocurrent measurements at varying external electric fields and carrier concentrations establish that drift-diffusion currents dominate photothermoelectric currents in devices under bias.
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elucidating the photoresponse of ultrathin mos2 field effect transistors by scanning Photocurrent microscopy
arXiv: Mesoscale and Nanoscale Physics, 2013Co-Authors: Deep Jariwala, Vinod K Sangwan, Tobin J Marks, Mark C Hersam, Lincoln J LauhonAbstract:The mechanisms underlying the intrinsic photoresponse of few-layer (FL) molybdenum disulphide (MoS2) field-effect transistors are investigated via scanning Photocurrent microscopy. We attribute the locally enhanced Photocurrent to band-bending assisted separation of photoexcited carriers at the MoS2/Au interface. The wavelength-dependent Photocurrents of few layer MoS2 transistors qualitatively follow the optical absorption spectra of MoS2, providing direct evidence of interband photoexcitation. Time and spectrally resolved Photocurrent measurements at varying external electric fields and carrier concentrations establish that drift-diffusion currents dominate photothermoelectric currents in devices under bias.
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near field scanning Photocurrent microscopy of a nanowire photodetector
Applied Physics Letters, 2005Co-Authors: E S Kwak, J L Lensch, Jonathan E Allen, Teri W Odom, Lincoln J LauhonAbstract:A near-field scanning optical microscope was used to image the Photocurrent induced by local illumination along the length of a metal-semiconductor-metal (MSM) photodetector made from an individual CdS nanowire. Nanowire MSM photodetectors exhibited Photocurrents ∼105 larger than the dark current (<2pA) under uniform monochromatic illumination; under local illumination, the photoresponse was localized to the near-contact regions. Analysis of the spatial variation and bias dependence of the local Photocurrent allowed the mechanisms of photocarrier transport and collection to be identified, highlighting the importance of near-field scanning Photocurrent microscopy to elucidating the operating principles of nanowire devices.
Patrick A. Lee - One of the best experts on this subject based on the ideXlab platform.
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Photocurrents in Weyl semimetals
Physical Review B, 2017Co-Authors: Ching-kit Chan, Netanel H. Lindner, Gil Refael, Patrick A. LeeAbstract:The generation of Photocurrent in an ideal two-dimensional Dirac spectrum is symmetry forbidden. In sharp contrast, we show that three-dimensional Weyl semimetals can generically support significant Photocurrents due to the combination of inversion symmetry breaking and finite tilts of the Weyl spectra. Symmetry properties, chirality relations, and various dependencies of this photovoltaic effect on the system and the light source are explored in detail. Our results suggest that noncentrosymmetric Weyl materials can be advantageously applied to room temperature detections of mid- and far-infrared radiations.
Hyun C. Lee - One of the best experts on this subject based on the ideXlab platform.
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Theoretical study of the Photocurrent in transition-metal dichalcogenide materials
Physical Review B, 2017Co-Authors: Hyun C. LeeAbstract:Motivated by Photocurrent spectroscopy experiments with $\mathrm{Mo}{\mathrm{S}}_{2}$, the direct band-to-band transition contribution to the Photocurrent of transition-metal dichalcogenides is computed starting from the microscopic Hamiltonian in the Keldysh-Schwinger formalism. It turns out that the band tilting induced by source to drain voltage is necessary for a nonvanishing Photocurrent. The photon energy dependence of the normalized Photocurrent is found to be consistent with experimental data. For circular polarization the helicity-dependent component of the Photocurrent perpendicular to the band-tilting direction is predicted, which essentially originates from the valley Hall effect.
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On the photon-drag effect of Photocurrent of surface states of topological insulators
Physica E: Low-dimensional Systems and Nanostructures, 2016Co-Authors: Hyun C. LeeAbstract:Abstract The Photocurrent of surface states of topological insulator due to photon-drag effect is computed, being based on pure Dirac model of surface states. The scattering by disorder is taken into account to provide a relaxation mechanism for the Photocurrent. The Keldysh–Schwinger formalism has been employed for the systematic calculation of Photocurrent. The helicity dependent Photocurrent of sizable magnitude transverse to the in-plane photon momentum is found, which is consistent with experimental data. Other helicity independent Photocurrents with various polarization states are also calculated.
Jean-pierre Petit - One of the best experts on this subject based on the ideXlab platform.
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Effect of interfacial oxide thickness on the photocatalytic activity of magnetron-sputtered TiO2 coatings on aluminum substrate
physica status solidi (a), 2015Co-Authors: Svava Davíðsdóttir, Klaus P. Almtoft, Inge H. Andersen, Stela Canulescu, Jean-pierre Petit, Rajashekhara Shabadi, Kai Dirscherl, Rajan AmbatAbstract:The influence of the coating/substrate interface on the photocatalytic behavior of Al-TiO2 coatings was investigated. The TiO2 coatings were prepared by magnetron sputtering. The nanoscale structure of the coating was analyzed using X-ray diffraction; atomic force microscopy; scanning electron microscopy; andtransmission electronmicroscopy. Thephotocatalytic behavior was investigated through optical spectrophotometry studies and electrochemical experiments; as photo voltage; Photocurrent; and electrochemical impedance measurements. Consistent results from both optical and electrochemical measurements showed a maximum UV-light absorption by titanium dioxide occurring slightly prior to the energy of the maximum Photocurrent. The Photocurrent of titanium dioxide decreases with increasing thickness of the aluminum oxide interface layer. Aluminumoxide acts as an insulator; disfavoring the electron transport between the coating and the metallic substrate. The highest Photocurrents were indeed obtained when the thickness of interfacial aluminum oxide could be reduced by sputtering a thin Ti layer prior to TiO2 coating. [GRAPHICS] Photocurrent plotted for different photon energy for a TiO2 coating on a Ti interlayer consisting of both rutile and anatase. Two photon-excitation peaks from the TiO2 coating (anatase and rutile) are observed at a potential of 0.34V versus SHE, while only one peak was observed at a potential 0.14V versus SHE closer to the conduction band. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Influence of oxidation time on semiconductive behaviour of thermally grown oxide films on AISI 304L
Applied Surface Science, 2006Co-Authors: L. Hamadou, A. Kadri, D. Boughara, Jean-pierre PetitAbstract:The oxide films formed on AISI 304L stainless steel at 300 °C in the oxidation time range between 2 and 4 h have been studied by photoelectrochemistry. Photocurrents were investigated as a function of the wavelength of the incident light and the electrode potential. The investigation allowed the determination of the semiconductive properties of the oxides. The oxide films showed n-type behaviour. A duplex structure of the oxide films has been suggested on the basis of the Photocurrent spectra, with an internal oxide layer having an optical gap (Eg2 = 2.16–2.3 eV) depending on the applied potential and oxidation time, higher to that of the external oxide layer (Eg1 ≈ 1.9 eV). Significant variations in the amplitude of the Photocurrent were detected as a function of the applied potential and the oxidation time.
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Photosensitization of Boron-Doped Diamond by Surface Grafting of Pyrene Groups
Electrochemical and Solid-State Letters, 2005Co-Authors: Pierre Bouvier, Didier Delabouglise, Alain Denoyelle, Bernadette Marcus, Michel Mermoux, Jean-pierre PetitAbstract:Boron-doped diamond samples were exposed successively to singlet oxygen and pyrene-alkylcarboxylic acid molecules. The resulting samples were studied by photoelectrochemistry. It is shown that the expected esterification reaction indeed allowed the grafting of pyrene groups onto the diamond surface. Cathodic Photocurrents have been obtained with quantum yields as high as η=0.29% (λ=351 nm, U=-0.38 V vs. a saturated calomel electrode) in oxygen saturated electrolyte. The pyrene coverage is estimated from both Photocurrent and photopotential measurements. The role of dissolved oxygen in the Photocurrent generation is discussed.
Deep Jariwala - One of the best experts on this subject based on the ideXlab platform.
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elucidating the photoresponse of ultrathin mos2 field effect transistors by scanning Photocurrent microscopy
Journal of Physical Chemistry Letters, 2013Co-Authors: Deep Jariwala, Vinod K Sangwan, Tobin J Marks, Mark C Hersam, Lincoln J LauhonAbstract:The mechanisms underlying the intrinsic photoresponse of few-layer (FL) molybdenum disulfide (MoS2) field-effect transistors are investigated via scanning Photocurrent microscopy. We attribute the locally enhanced Photocurrent to band-bending-assisted separation of photoexcited carriers at the MoS2/Au interface. The wavelength-dependent Photocurrents of FL MoS2 transistors qualitatively follow the optical absorption spectra of MoS2, providing direct evidence of interband photoexcitation. Time and spectrally resolved Photocurrent measurements at varying external electric fields and carrier concentrations establish that drift-diffusion currents dominate photothermoelectric currents in devices under bias.
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elucidating the photoresponse of ultrathin mos2 field effect transistors by scanning Photocurrent microscopy
arXiv: Mesoscale and Nanoscale Physics, 2013Co-Authors: Deep Jariwala, Vinod K Sangwan, Tobin J Marks, Mark C Hersam, Lincoln J LauhonAbstract:The mechanisms underlying the intrinsic photoresponse of few-layer (FL) molybdenum disulphide (MoS2) field-effect transistors are investigated via scanning Photocurrent microscopy. We attribute the locally enhanced Photocurrent to band-bending assisted separation of photoexcited carriers at the MoS2/Au interface. The wavelength-dependent Photocurrents of few layer MoS2 transistors qualitatively follow the optical absorption spectra of MoS2, providing direct evidence of interband photoexcitation. Time and spectrally resolved Photocurrent measurements at varying external electric fields and carrier concentrations establish that drift-diffusion currents dominate photothermoelectric currents in devices under bias.
