The Experts below are selected from a list of 7164 Experts worldwide ranked by ideXlab platform
Phillip D Keathley - One of the best experts on this subject based on the ideXlab platform.
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impact of dc bias on weak optical field driven electron emission in nano vacuum gap detectors
Journal of The Optical Society of America B-optical Physics, 2021Co-Authors: Marco Turchetti, M R Bionta, Yujia Yang, Felix Ritzkowsky, Denis R Candido, Michael E Flatte, Karl K Berggren, Phillip D KeathleyAbstract:In this work, we investigate multiphoton and optical field tunneling emission from metallic surfaces with nanoscale vacuum gaps. Using time-dependent Schrodinger equation (TDSE) simulations, we find that the properties of the emitted photocurrent in such systems can be greatly altered by the application of only a few-volt direct current (DC) bias. We find that when coupled with expected plasmonic enhancements within the nanometer-scale metallic gaps, the application of this DC bias significantly reduces the threshold for the transition to optical-field-driven tunneling from the metal surface, and could sufficiently enhance the emitted Photocurrents, to make it feasible to electronically tag fJ ultrafast pulses at room temperature. Given the petahertz-scale instantaneous response of the Photocurrents, and the low effective capacitance of thin-film nanoantenna devices that enables <1fs response time, detectors that exploit this bias-enhanced surface emission from nanoscale vacuum gaps could prove to be useful for communication, petahertz electronics, and ultrafast optical-field-resolved metrology.
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impact of dc bias on weak optical field driven electron emission in nano vacuum gap detectors
arXiv: Optics, 2020Co-Authors: Marco Turchetti, M R Bionta, Yujia Yang, Felix Ritzkowsky, Denis R Candido, Michael E Flatte, Karl K Berggren, Phillip D KeathleyAbstract:In this work, we investigate multiphoton and optical-field tunneling emission from metallic surfaces with nanoscale vacuum gaps. Using time-dependent Schrodinger equation (TDSE) simulations, we find that the properties of the emitted photocurrent in such systems can be greatly altered by the application of only a few-volt DC bias. We find that when coupled with expected plasmonic enhancements within the nanometer-scale metallic gaps, the application of this DC bias significantly reduces the threshold for the transition to optical-field-driven tunneling from the metal surface, and could sufficiently enhance the emitted Photocurrents, to make it feasible to electronically tag fJ ultrafast pulses at room temperature. Given the petahertz-scale instantaneous response of the Photocurrents, and the low effective capacitance of thin-film nanoantenna devices that enables < 1 fs response time, detectors that exploit this bias-enhanced surface emission from nanoscale vacuum gaps could prove to be useful for communication, petahertz electronics, and ultrafast optical-field-resolved metrology.
Marco Turchetti - One of the best experts on this subject based on the ideXlab platform.
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impact of dc bias on weak optical field driven electron emission in nano vacuum gap detectors
Journal of The Optical Society of America B-optical Physics, 2021Co-Authors: Marco Turchetti, M R Bionta, Yujia Yang, Felix Ritzkowsky, Denis R Candido, Michael E Flatte, Karl K Berggren, Phillip D KeathleyAbstract:In this work, we investigate multiphoton and optical field tunneling emission from metallic surfaces with nanoscale vacuum gaps. Using time-dependent Schrodinger equation (TDSE) simulations, we find that the properties of the emitted photocurrent in such systems can be greatly altered by the application of only a few-volt direct current (DC) bias. We find that when coupled with expected plasmonic enhancements within the nanometer-scale metallic gaps, the application of this DC bias significantly reduces the threshold for the transition to optical-field-driven tunneling from the metal surface, and could sufficiently enhance the emitted Photocurrents, to make it feasible to electronically tag fJ ultrafast pulses at room temperature. Given the petahertz-scale instantaneous response of the Photocurrents, and the low effective capacitance of thin-film nanoantenna devices that enables <1fs response time, detectors that exploit this bias-enhanced surface emission from nanoscale vacuum gaps could prove to be useful for communication, petahertz electronics, and ultrafast optical-field-resolved metrology.
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impact of dc bias on weak optical field driven electron emission in nano vacuum gap detectors
arXiv: Optics, 2020Co-Authors: Marco Turchetti, M R Bionta, Yujia Yang, Felix Ritzkowsky, Denis R Candido, Michael E Flatte, Karl K Berggren, Phillip D KeathleyAbstract:In this work, we investigate multiphoton and optical-field tunneling emission from metallic surfaces with nanoscale vacuum gaps. Using time-dependent Schrodinger equation (TDSE) simulations, we find that the properties of the emitted photocurrent in such systems can be greatly altered by the application of only a few-volt DC bias. We find that when coupled with expected plasmonic enhancements within the nanometer-scale metallic gaps, the application of this DC bias significantly reduces the threshold for the transition to optical-field-driven tunneling from the metal surface, and could sufficiently enhance the emitted Photocurrents, to make it feasible to electronically tag fJ ultrafast pulses at room temperature. Given the petahertz-scale instantaneous response of the Photocurrents, and the low effective capacitance of thin-film nanoantenna devices that enables < 1 fs response time, detectors that exploit this bias-enhanced surface emission from nanoscale vacuum gaps could prove to be useful for communication, petahertz electronics, and ultrafast optical-field-resolved metrology.
Ioanna Zergioti - One of the best experts on this subject based on the ideXlab platform.
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Functionalization of gold screen printed electrodes with bacterial photosynthetic reaction centers by laser printing technology for mediatorless herbicide biosensing
Electrochemistry Communications, 2016Co-Authors: Marianneza Chatzipetrou, Livia Giotta, Daniela Chirizzi, Maria Massaouti, Maria Rachele Guascito, Massimo Trotta, Francesco Milano, Ioanna ZergiotiAbstract:Abstract The development of an amperometric biosensor for herbicide detection, using bacterial reaction centers (RC) as biorecognition element, is presented. RC immobilization on gold screen printed electrodes was achieved by LIFT, a powerful physisorption-based immobilization technique that enhances the intimate contact between the protein and the electrode surface. As a result, stable Photocurrents driven by direct electron transfer at the donor side were observed, both in the presence and in the absence of a quinone substrate in solution. The addition of quinone UQ0 increased the Photocurrents, while the UQ0-free system showed higher sensitivity to the herbicide terbutryn, a model inhibitor, acting as photocurrent attenuator. In spite of its simple design, the performances achieved by our mediatorless device are comparable or superior to those reported for analogous RC-based photoelectrochemical cells, in terms of both terbutryn sensing and photocurrent generation.
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Functionalization of gold screen printed electrodes with bacterial photosynthetic reaction centers by laser printing technology for mediatorless herbicide biosensing
Elsevier, 2016Co-Authors: Marianneza Chatzipetrou, Livia Giotta, Daniela Chirizzi, Maria Massaouti, Massimo Trotta, Francesco Milano, Ioanna ZergiotiAbstract:The development of an amperometric biosensor for herbicide detection, using bacterial reaction centers (RC) as biorecognition element, is presented. RC immobilization on gold screen printed electrodes was achieved by LIFT, a powerful physisorption-based immobilization technique that enhances the intimate contact between the protein and the electrode surface. As a result, stable Photocurrents driven by direct electron transfer at the donor side were observed, both in the presence and in the absence of a quinone substrate in solution. The addition of quinone UQ0 increased the Photocurrents, while the UQ0-free system showed higher sensitivity to the herbicide terbutryn, a model inhibitor, acting as photocurrent attenuator. In spite of its simple design, the performances achieved by our mediatorless device are comparable or superior to those reported for analogous RC-based photoelectrochemical cells, in terms of both terbutryn sensing and photocurrent generation. Keywords: LIFT, Reaction center, Rhodobacter, Photocurrent, Inhibition, Herbicid
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.
Dmitri Golberg - One of the best experts on this subject based on the ideXlab platform.
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statistically analyzed photoresponse of elastically bent cds nanowires probed by light compatible in situ high resolution tem
Nano Letters, 2016Co-Authors: Chao Zhang, Ovidiu Cretu, Dmitry G Kvashnin, Naoyuki Kawamoto, Masanori Mitome, Xi Wang, Yoshio Bando, P Sorokin, Dmitri GolbergAbstract:We demonstrate that high resolution transmission electron microscopy (HRTEM) paired with light illumination of a sample and its electrical probing can be utilized for the in situ study of initiated Photocurrents in free-standing nanowires. Morphology, phase and crystallographic information from numerous individual CdS nanowires is obtained simultaneously with photocurrent measurements. Our results indicate that elastically bent CdS nanowires possessing a wurtzite structure show statistically unchanged values of ON/OFF (photocurrent/dark current) ratios. Photocurrent spectroscopy reveals red shifts of several nanometers in the cutoff wavelength after nanowire bending. This results from deformation-induced lattice strain and associated changes in the nanowire band structure, as confirmed by selected area electron diffraction (SAED) analyses and density functional tight binding (DFTB) simulations. The ON/OFF ratio stabilities and photocurrent spectroscopy shift of bent CdS nanowires are important clues for f...
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statistically analyzed photoresponse of elastically bent cds nanowires probed by light compatible in situ high resolution tem
Science & Engineering Faculty, 2016Co-Authors: Chao Zhang, Ovidiu Cretu, Dmitry G Kvashnin, Naoyuki Kawamoto, Masanori Mitome, Xi Wang, Yoshio Bando, P Sorokin, Dmitri GolbergAbstract:We demonstrate that high resolution transmission electron microscopy (HRTEM) paired with light illumination of a sample and its electrical probing can be utilized for the in situ study of initiated Photocurrents in free-standing nanowires. Morphology, phase and crystallographic information from numerous individual CdS nanowires is obtained simultaneously with photocurrent measurements. Our results indicate that elastically bent CdS nanowires possessing a wurtzite structure show statistically unchanged values of ON/OFF (photocurrent/dark current) ratios. Photocurrent spectroscopy reveals red shifts of several nanometers in the cutoff wavelength after nanowire bending. This results from deformation-induced lattice strain and associated changes in the nanowire band structure, as confirmed by selected area electron diffraction (SAED) analyses and density functional tight binding (DFTB) simulations. The ON/OFF ratio stabilities and photocurrent spectroscopy shift of bent CdS nanowires are important clues for future flexible electronics, optoelectronics, and photovoltaics.
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in situ fabrication and optoelectronic analysis of axial cds p si nanowire heterojunctions in a high resolution transmission electron microscope
Science & Engineering Faculty, 2015Co-Authors: Chao Zhang, Xi Wang, Yoshio Bando, Wei Tian, Daiming Tang, Naoki Fukata, Dmitri GolbergAbstract:A high-precision technique was utilized to construct and characterize axial nanowire heterojunctions inside a high-resolution transmission electron microscope (HRTEM). By an in-tandem technique using an ultra-sharp tungsten probe as the nanomanipulator and an optical fiber as the optical waveguide the nanoscale CdS/p-Si axial nanowire junctions were fabricated, and in situ Photocurrents from them were successfully measured. Compared to a single constituting nanowire, the CdS/p-Si axial nanowire junctions possess a photocurrent saturation effect, which protects them from damage under high voltages. Furthermore, a set of experiments reveals the clear relationship between the saturation photocurrent values and the incident light intensities. The applied technique is expected to be valuable for bottom-up nanodevice fabrications, and the regarded photocurrent saturation feature may solve the Joule heating-induced failure problem in nanowire optoelectronic devices caused by a fluctuating bias.