The Experts below are selected from a list of 2874 Experts worldwide ranked by ideXlab platform
A K Raychaudhuri - One of the best experts on this subject based on the ideXlab platform.
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Single Silicon Nanowire based Broadband Photodetector with Superior Responsivity
Photonics, 2014Co-Authors: Subhrajit Mukherjee, Abhijit Kakati, A K RaychaudhuriAbstract:Single-silicon-Nanowire based MSM photodetectors show superior response (>10000 A/W) even without external bias in visible-to-near-IR region. The responsivity improvement as function of Nanowire Diameter has been explained by electric-field enhancement using finite-element based optical simulation.
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Single Si Nanowire (Diameter ≤ 100 nm) based polarization sensitive near-infrared photodetector with ultra-high responsivity
Nanoscale, 2014Co-Authors: Subhrajit Mukherjee, S Manna, A K RaychaudhuriAbstract:We report the fabrication and optical response of boron-doped single silicon Nanowire-based metal–semiconductor–metal photodetector. Typical single Nanowire devices with Diameter of ∼80–100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from Nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 104 A W−1, was observed even at zero bias in a single Nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing Nanowire Diameter. Finite element based optical simulation was proposed to explain the Diameter dependent performance of a single Nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector.
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single si Nanowire Diameter 100 nm based polarization sensitive near infrared photodetector with ultra high responsivity
Nanoscale, 2014Co-Authors: Subhrajit Mukherjee, S Manna, A K RaychaudhuriAbstract:We report the fabrication and optical response of boron-doped single silicon Nanowire-based metal–semiconductor–metal photodetector. Typical single Nanowire devices with Diameter of ∼80–100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from Nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 104 A W−1, was observed even at zero bias in a single Nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing Nanowire Diameter. Finite element based optical simulation was proposed to explain the Diameter dependent performance of a single Nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector.
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low frequency flicker noise in a msm device made with single si Nanowire Diameter 50 nm
Nanoscale Research Letters, 2013Co-Authors: Sudeshna Samanta, A K RaychaudhuriAbstract:Low-frequency flicker noise has been measured in a metal-semiconductor-metal (MSM) device made from a single strand of a single crystalline Si Nanowire (Diameter approximately 50 nm). Measurement was done with an alternating current (ac) excitation for the noise measurement superimposed with direct current (dc) bias that can be controlled independently. The observed noise has a spectral power density ∝ 1/f α . Application of the superimposed dc bias (retaining the ac bias unchanged) with a value more than the Schottky barrier height at the junction leads to a large suppression of the noise amplitude along with a change of α from 2 to ≈ 1. The dc bias-dependent part of the noise has been interpreted as arising from the interface region. The residual dc bias-independent flicker noise is suggested to arise from the single strand of Si Nanowire, which has the conventional 1/f spectral power density.
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Low-frequency flicker noise in a MSM device made with single Si Nanowire (Diameter ≈ 50 nm)
Nanoscale Research Letters, 2013Co-Authors: Sudeshna Samanta, A K RaychaudhuriAbstract:Low-frequency flicker noise has been measured in a metal-semiconductor-metal (MSM) device made from a single strand of a single crystalline Si Nanowire (Diameter approximately 50 nm). Measurement was done with an alternating current (ac) excitation for the noise measurement superimposed with direct current (dc) bias that can be controlled independently. The observed noise has a spectral power density ∝ 1/f α . Application of the superimposed dc bias (retaining the ac bias unchanged) with a value more than the Schottky barrier height at the junction leads to a large suppression of the noise amplitude along with a change of α from 2 to ≈ 1. The dc bias-dependent part of the noise has been interpreted as arising from the interface region. The residual dc bias-independent flicker noise is suggested to arise from the single strand of Si Nanowire, which has the conventional 1/f spectral power density.
Subhrajit Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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Single Silicon Nanowire based Broadband Photodetector with Superior Responsivity
Photonics, 2014Co-Authors: Subhrajit Mukherjee, Abhijit Kakati, A K RaychaudhuriAbstract:Single-silicon-Nanowire based MSM photodetectors show superior response (>10000 A/W) even without external bias in visible-to-near-IR region. The responsivity improvement as function of Nanowire Diameter has been explained by electric-field enhancement using finite-element based optical simulation.
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Single Si Nanowire (Diameter ≤ 100 nm) based polarization sensitive near-infrared photodetector with ultra-high responsivity
Nanoscale, 2014Co-Authors: Subhrajit Mukherjee, S Manna, A K RaychaudhuriAbstract:We report the fabrication and optical response of boron-doped single silicon Nanowire-based metal–semiconductor–metal photodetector. Typical single Nanowire devices with Diameter of ∼80–100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from Nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 104 A W−1, was observed even at zero bias in a single Nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing Nanowire Diameter. Finite element based optical simulation was proposed to explain the Diameter dependent performance of a single Nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector.
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single si Nanowire Diameter 100 nm based polarization sensitive near infrared photodetector with ultra high responsivity
Nanoscale, 2014Co-Authors: Subhrajit Mukherjee, S Manna, A K RaychaudhuriAbstract:We report the fabrication and optical response of boron-doped single silicon Nanowire-based metal–semiconductor–metal photodetector. Typical single Nanowire devices with Diameter of ∼80–100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from Nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 104 A W−1, was observed even at zero bias in a single Nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing Nanowire Diameter. Finite element based optical simulation was proposed to explain the Diameter dependent performance of a single Nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector.
Ali Javey - One of the best experts on this subject based on the ideXlab platform.
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Formation and characterization of NixInAs/InAs Nanowire heterostructures by solid source reaction.
Nano Letters, 2008Co-Authors: Yu-lun Chueh, Zachery A Jacobson, Alexandra C. Ford, Li Jen Chou, Johnny C. Ho, Chih-yen Chen, Ali JaveyAbstract:The formation of crystalline NixInAs and NixInAs/InAs/NixInAs heterostructure Nanowires by the solid source reaction of InAs Nanowires with Ni is reported for the first time. The fundamental kinetics of the Ni/InAs alloying reaction is explored, with the Ni diffusion reported as the rate determining step. The diffusivity of Ni is independent of the Nanowire Diameter, with an extracted diffusion activation energy of ∼1 eV/atom. The metallic NixInAs exhibits a modest resistivity of ∼167 μΩ·cm for Diameters >30 nm, with the resistivity increasing as the Nanowire Diameter is further reduced due to the enhanced surface scattering. The alloying reaction readily enables the fabrication of NixInAs/InAs/NixInAs heterostructure Nanowire transistors for which the length of the InAs segment (i.e., channel length) is controllably reduced through subsequent thermal annealing steps, therefore enabling a systematic study of electrical properties as a function of channel length. From the electrical transport studies, an e...
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Formation and characterization of NixInAs/InAs Nanowire heterostructures by solid source reaction.
Nano letters, 2008Co-Authors: Yu-lun Chueh, Zachery A Jacobson, Alexandra C. Ford, Li Jen Chou, Johnny C. Ho, Zhiyong Fan, Chih-yen Chen, Ali JaveyAbstract:The formation of crystalline NixInAs and NixInAs/InAs/NixInAs heterostructure Nanowires by the solid source reaction of InAs Nanowires with Ni is reported for the first time. The fundamental kinetics of the Ni/InAs alloying reaction is explored, with the Ni diffusion reported as the rate determining step. The diffusivity of Ni is independent of the Nanowire Diameter, with an extracted diffusion activation energy of approximately 1 eV/atom. The metallic NixInAs exhibits a modest resistivity of approximately 167 micro omega x cm for Diameters >30 nm, with the resistivity increasing as the Nanowire Diameter is further reduced due to the enhanced surface scattering. The alloying reaction readily enables the fabrication of NixInAs/InAs/NixInAs heterostructure Nanowire transistors for which the length of the InAs segment (i.e., channel length) is controllably reduced through subsequent thermal annealing steps, therefore enabling a systematic study of electrical properties as a function of channel length. From the electrical transport studies, an electron mean free path on the order of a few hundred nm is observed for InAs NWs with a unit length normalized, ON-state resistance of approximately 7.5 k omega/microm. This approach presents a route toward the fabrication for high performance InAs Nanowire transistors with ohmic nanoscale contacts and low parasitic capacitances and resistances.
O Brandt - One of the best experts on this subject based on the ideXlab platform.
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Minimizing the influence of surface potentials in axial In x Ga 1−x N/GaN Nanowire heterostructures by reducing their Diameter
Numerical Simulation of Optoelectronic Devices 2014, 2014Co-Authors: Oliver Marquardt, Lutz Geelhaar, O BrandtAbstract:Simulations using continuum elasticity theory and an eight-band k · p approach suggest the reduction of the Diameter of In x Ga 1−x N/GaN axial Nanowire heterostructures to be a promising approach to increase the intensity of light emitting processes. A reduction of the Nanowire Diameter significantly reduces the magnitude of surface potentials and thus leads to a much larger overlap of the electron and hole charge densities.
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minimizing the impact of surface potentials in axial inxga1 xn gan Nanowire heterostructures by reducing their Diameter
Journal of Physics D, 2014Co-Authors: Oliver Marquardt, Lutz Geelhaar, O BrandtAbstract:We study the influence of the Diameter of axial InxGa1?xN/GaN Nanowire heterostructures on the electron and hole confinement in the InxGa1?xN quantum disk using an eight-band k???p model. Elastic relaxation as well as polarization and surface potentials are fully taken into account. Our calculations indicate that a reduction of the Nanowire Diameter diminishes the influence of the surface potential and thus leads to a significantly increased spatial overlap of electron and hole wave functions. The results suggest that a reduction of the Nanowire Diameter below 40?nm can significantly improve the internal quantum efficiency of Nanowire-based light emitters.
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Minimizing the impact of surface potentials in axial InxGa1−xN/GaN Nanowire heterostructures by reducing their Diameter
Journal of Physics D, 2014Co-Authors: Oliver Marquardt, Lutz Geelhaar, O BrandtAbstract:We study the influence of the Diameter of axial InxGa1?xN/GaN Nanowire heterostructures on the electron and hole confinement in the InxGa1?xN quantum disk using an eight-band k???p model. Elastic relaxation as well as polarization and surface potentials are fully taken into account. Our calculations indicate that a reduction of the Nanowire Diameter diminishes the influence of the surface potential and thus leads to a significantly increased spatial overlap of electron and hole wave functions. The results suggest that a reduction of the Nanowire Diameter below 40?nm can significantly improve the internal quantum efficiency of Nanowire-based light emitters.
Alec A. Talin - One of the best experts on this subject based on the ideXlab platform.
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Transport characterization in Nanowires using an electrical nanoprobe
Semiconductor Science and Technology, 2010Co-Authors: Alec A. Talin, Aaron M. Katzenmeyer, B. S. Swartzentruber, J. G. Cederberg, Stephen D. Hersee, Maria Eugenia Toimil-molares, S. Tom Picraux, François Léonard, Xiaodong Wang, A. RishinaramangalumAbstract:Electrical transport in semiconductor Nanowires is commonly measured in a field effect transistor configuration, with lithographically defined source, drain and in some cases, top gate electrodes. This approach is labor intensive, requires high-end fabrication equipment, exposes the Nanowires to extensive processing chemistry and places practical limitations on minimum Nanowire length. Here we describe an alternative, simple method for characterizing electrical transport in Nanowires directly on the growth substrate, without any need for post growth processing. Our technique is based on contacting Nanowires using a nano-manipulator probe retrofitted inside of a scanning electron microscope. Using this approach, we characterize electrical transport in GaN Nanowires grown by catalyst-free selective epitaxy, as well as InAs and Ge Nanowires grown by a Au-catalyzed vapor solid liquid technique. We find that in situations where contacts are not limiting carrier injection (GaN and InAs Nanowires), electrical transport transitions from Ohmic conduction at low bias to space-charge-limited conduction at higher bias. Using this transition and a theory of space-charge-limited transport which accounts for the high aspect ratio Nanowires, we extract the mobility and the free carrier concentration. For Ge Nanowires, we find that the Au catalyst forms a Schottky contact resulting in rectifying current-voltage characteristics, which are strongly dependent on the Nanowire Diameter. This dependence arises due to an increase in depletion width at decreased Nanowire Diameter and carrier recombination at the Nanowire surface.
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Diameter dependent electronic transport properties of au catalyst ge Nanowire schottky diodes
Physical Review Letters, 2009Co-Authors: François Léonard, B. S. Swartzentruber, Alec A. Talin, S. Tom PicrauxAbstract:We present electronic transport measurements in individual Au-catalyst/Ge-Nanowire interfaces demonstrating the presence of a Schottky barrier. Surprisingly, the small-bias conductance density increases with decreasing Diameter. Theoretical calculations suggest that this effect arises because electron-hole recombination in the depletion region is the dominant charge transport mechanism, with a Diameter dependence of both the depletion width and the electron-hole recombination time. The recombination time is dominated by surface contributions and depends linearly on the Nanowire Diameter.
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Size-dependent effects on electrical contacts to nanotubes and Nanowires
Physical Review Letters, 2006Co-Authors: François Léonard, Alec A. TalinAbstract:Metal-semiconductor contacts play a key role in electronics. Here we show that for quasi-one dimensional (Q1D) structures such as nanotubes and Nanowires, side contact with the metal only leads to weak band realignment, in contrast with bulk metal-semiconductor contacts. Schottky barriers are much reduced compared with the bulk limit, and should facilitate the formation of good contacts. However, the conventional strategy of heavily doping the semiconductor to obtain Ohmic contacts breaks down as the Nanowire Diameter is reduced. The issue of Fermi level pinning is also discussed, and it is demonstrated that the unique density of states of Q1D structures makes them less sensitive to this effect. Our results agree with recent experimental work, and should apply to a broad range of Q1D materials.
