The Experts below are selected from a list of 367632 Experts worldwide ranked by ideXlab platform
Thomas Frauenheim - One of the best experts on this subject based on the ideXlab platform.
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Silicon Nanowire Band Gap Modification
Nano Letters, 2020Co-Authors: Michael Nolan, Sean O'callaghan, James C. Greer, Giorgos Fagas, Thomas FrauenheimAbstract:Band Gap modification for small-diameter (∼1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct Band Gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the Band Gap, resulting in relative energy shifts of up to an electronvolt. The Band Gap shifts are traced to details of the hybridization between the silicon valence Band and the frontier orbitals of the terminating group, which is in competition with quantum confinement.
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Silicon nanowire Band Gap modification
Nano Letters, 2007Co-Authors: Michael Nolan, Sean O'callaghan, James C. Greer, Giorgos Fagas, Thomas FrauenheimAbstract:Band Gap modification for small-diameter (approximately 1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct Band Gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the Band Gap, resulting in relative energy shifts of up to an electronvolt. The Band Gap shifts are traced to details of the hybridization between the silicon valence Band and the frontier orbitals of the terminating group, which is in competition with quantum confinement.
Andriy Zakutayev - One of the best experts on this subject based on the ideXlab platform.
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Wide Band Gap Chalcogenide Semiconductors.
Chemical Reviews, 2020Co-Authors: Rachel Woods-robinson, Tursun Ablekim, Kristin A. Persson, Imran Khan, Hanyu Zhang, Andriy ZakutayevAbstract:Wide Band Gap semiconductors are essential for today’s electronic devices and energy applications because of their high optical transparency, controllable carrier concentration, and tunable electri...
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Wide Band Gap chalcogenide semiconductors.
arXiv: Materials Science, 2020Co-Authors: Rachel Woods-robinson, Tursun Ablekim, Kristin A. Persson, Imran Khan, Hanyu Zhang, Andriy ZakutayevAbstract:Wide Band Gap semiconductors are essential for today's electronic devices and energy applications due to their high optical transparency, as well as controllable carrier concentration and electrical conductivity. There are many categories of materials that can be defined as wide Band Gap semiconductors. The most intensively investigated are transparent conductive oxides (TCOs) such as ITO and IGZO used in displays, carbides and nitrides used in power electronics, as well as emerging halides (e.g. CuI) and 2D electronic materials used in various optoelectronic devices. Chalcogen-based (S, Se, Te) wide Band Gap semiconductors are less heavily investigated but stand out due to their propensity for p-type doping, high mobilities, high valence Band positions (i.e. low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide Band Gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent conductors. We proceed to summarize progress in wide Band Gap (Eg > 2 eV) chalcogenide materials, such as II-VI MCh binaries, CuMCh2 chalcopyrites, Cu3MCh4 sulvanites, mixed anion layered CuMCh(O,F), and 2D materials, among others, and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications of chalcogenide wide Band Gap semiconductors, e.g. photovoltaic and photoelectrochemical solar cells, transparent transistors, and diodes, that employ wide Band Gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide Band Gap chalcogenides, this review aims to inspire continued research on this emerging class of transparent conductors and to enable future innovations for optoelectronic devices.
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Review of wide Band Gap chalcogenide semiconductors.
arXiv: Materials Science, 2019Co-Authors: Rachel Woods-robinson, Tursun Ablekim, Yanbing Han, Kristin A. Persson, Imran Khan, Hanyu Zhang, Andriy ZakutayevAbstract:Wide Band Gap semiconductors are essential for today's electronic devices and energy applications due to their high optical transparency, as well as controllable carrier concentration and electrical conductivity. There are many categories of materials that can be defined as wide Band Gap semiconductors. The most intensively investigated are transparent conductive oxides (TCOs) such as ITO and IGZO used in displays, carbides and nitrides used in power electronics, as well as emerging halides (e.g. CuI) and 2D electronic materials used in various optoelectronic devices. Chalcogen-based (S, Se, Te) wide Band Gap semiconductors are less heavily investigated but stand out due to their propensity for p-type doping, high mobilities, high valence Band positions (i.e. low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide Band Gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent conductors. We proceed to summarize progress in wide Band Gap (Eg > 2 eV) chalcogenide materials, such as II-VI MCh binaries, CuMCh2 chalcopyrites, Cu3MCh4 sulvanites, mixed anion layered CuMCh(O,F), and 2D materials, among others, and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications of chalcogenide wide Band Gap semiconductors, e.g. photovoltaic and photoelectrochemical solar cells, transparent transistors, and diodes, that employ wide Band Gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide Band Gap chalcogenides, this review aims to inspire continued research on this emerging class of transparent conductors and to enable future innovations for optoelectronic devices.
Michael Nolan - One of the best experts on this subject based on the ideXlab platform.
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Silicon Nanowire Band Gap Modification
Nano Letters, 2020Co-Authors: Michael Nolan, Sean O'callaghan, James C. Greer, Giorgos Fagas, Thomas FrauenheimAbstract:Band Gap modification for small-diameter (∼1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct Band Gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the Band Gap, resulting in relative energy shifts of up to an electronvolt. The Band Gap shifts are traced to details of the hybridization between the silicon valence Band and the frontier orbitals of the terminating group, which is in competition with quantum confinement.
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Silicon nanowire Band Gap modification
Nano Letters, 2007Co-Authors: Michael Nolan, Sean O'callaghan, James C. Greer, Giorgos Fagas, Thomas FrauenheimAbstract:Band Gap modification for small-diameter (approximately 1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct Band Gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the Band Gap, resulting in relative energy shifts of up to an electronvolt. The Band Gap shifts are traced to details of the hybridization between the silicon valence Band and the frontier orbitals of the terminating group, which is in competition with quantum confinement.
Vladimir I Falko - One of the best experts on this subject based on the ideXlab platform.
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electrically tunable Band Gap in silicene
Physical Review B, 2012Co-Authors: Neil Drummond, Viktor Zolyomi, Vladimir I FalkoAbstract:We report calculations of the electronic structure of silicene and the stability of its weakly buckled honeycomb lattice in an external electric field oriented perpendicular to the monolayer of Si atoms. The electric field produces a tunable Band Gap in the Dirac-type electronic spectrum, the Gap being suppressed by a factor of about eight by the high polarizability of the system. At low electric fields, the interplay between this tunable Band Gap, which is specific to electrons on a honeycomb lattice, and the Kane-Mele spin-orbit coupling induces a transition from a topological to a Band insulator, whereas at much higher electric fields silicene becomes a semimetal.
Jing Guo - One of the best experts on this subject based on the ideXlab platform.
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Band Gap of strained graphene nanoribbons
Nano Research, 2010Co-Authors: Yang Lu, Jing GuoAbstract:The Band structures of strained graphene nanoribbons (GNRs) are examined by a tight binding Hamiltonian that is directly related to the type and strength of strains. Compared to the two-dimensional graphene whose Band Gap remains close to zero even if a large strain is applied, the Band Gap of graphene nanoribbon (GNR) is sensitive to both uniaxial and shears strains. The effect of strain on the electronic structure of a GNR strongly depends on its edge shape and structural indices. For an armchair GNR, uniaxial weak strain changes the Band Gap in a linear fashion, and for a large strain, it results in periodic oscillation of the Band Gap. On the other hand, shear strain always tend to reduce the Band Gap. For a zigzag GNR, the effect of strain is to change the spin polarization at the edges of GNR, thereby modulate the Band Gap. A simple analytical model is proposed to interpret the Band Gap responds to strain in armchair GNR, which agrees with the numerical results.
