Optical transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Pb</mml:mi><mml:mi mathvariant="normal">Te</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Cd</mml:mi><mml:mi mathvariant="normal">Te</mml:mi></mml:mrow></mml:math>quantum dots

Xu, Tianning; Wu, Honghui; X., J.; McCann, Patrick J.

doi:10.1103/physrevb.76.155328

Cited by 23 publications

(6 citation statements)

References 23 publications

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“…On heating to T = 25 K, the resonance disappears, with spectral weight moving into the gap. The Q dependence of the spectrum is still narrow around ω ∼ 5 to 6 meV, but appears to disperse outwards for energies both above and below, similar to the those observed in the cuprates [22][23][24]30 . With further heating, the spin excitations near the saddle point (∼ 5 meV) start to split in Q and become clearly incommensurate, exhibiting a "waterfall" structure at 100 K and above, similar to the situation in underdoped YBa 2 Cu 3 O 6+x 24 .…”

supporting

confidence: 64%

Local-moment magnetism in superconducting FeTe0.35Se0.65as seen via inelastic neutron scattering

Wen

et al. 2011

Phys. Rev. B

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supporting

confidence: 64%

Local-moment magnetism in superconducting FeTe0.35Se0.65as seen via inelastic neutron scattering

Wen

et al. 2011

Phys. Rev. B

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“…Although this approach to make PbX/CdX heteronanostructures has been followed by various authors, − few studies have addressed the optical properties of PbX/CdX core/shell quantum dots. Only for the case of PbSe/CdSe QDs are extinction coefficients and a sizing curve available, allowing for the determination of the core diameter from the absorption spectrum, whereas a detailed study by de Geyter et al gave evidence of significant electron delocalization in the shell and an enhanced splitting of the exciton fine structure .…”

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confidence: 99%

Optical Properties of PbS/CdS Core/Shell Quantum Dots

et al. 2013

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We determine the optical properties of PbS/CdS core/shell QDs, addressing the energy and the oscillator strength of the first exciton transition and the intrinsic absorption coefficient at short wavelengths. It follows that the intrinsic absorption coefficient at wavelengths of 350 and 400 nm agrees with theoretical numbers predicted using the Maxwell–Garnett model. Moreover, close correspondence is demonstrated between the energy and the oscillator strength of the first exciton transition of PbS/CdS core/shell and PbS QDs with a similar core size. This provides a straightforward way to estimate the PbS core diameter in PbS/CdS core/shell quantum dots by means of the PbS sizing curve, and it indicates that PbS/CdS QDs exhibit a type 1 band alignment.

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“…Usually experiments and theories describe 1,2,3,4 the direct allowed transitions in terms of the Fermi golden rule which provides the imaginary part of the dielectric function (or the real conductivity)…”

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confidence: 99%

Features of interband absorption in the dielectric function of narrow-gap semiconductors

Falkovsky

2008

Phys. Rev. B

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For semiconductors and semimetals possessing a narrow gap between bands with different parity, the dispersion of the dielectric function is explicitly evaluated in the infrared region. The imaginary part of the dielectric function has a plateau above the absorption threshold for the interband electron transitions. The real part of the dielectric function has a logarithmic singularity at the threshold. This results in the large contribution into the dielectric constant for pure semiconductors at low frequencies. For samples with degenerate carriers, the real part of the dielectric function is divergent at the absorption threshold. This divergence is smeared with the temperature or the collision rate. PACS numbers: 71.20.Nr, 78.20.Ci, 78.20.Bh Usually experiments and theories describe 1,2,3,4 the direct allowed transitions in terms of the Fermi golden rule which provides the imaginary part of the dielectric function (or the real conductivity)giving the square root dependence ǫ ′′ (ω) ∼ hω − 2ε g near the band edge absorption for the case when the conduction band is empty and the valence band is filled. The electron-hole Coulomb interaction smears this squareroot singularity. For doped semiconductors, the threshold of absorption is determined by the carrier concentration, i.e., the chemical potential µ if the temperature is low enough. The interband transitions of carriers give also a contribution into the real part ǫ ′ (ω) which can be calculated with the help of the Kramers-Kronig relations. In reality, these numerical calculations involve the pseudopotential form-factor and do not present an evident result (see, for instance, Ref. 1,2 ). It is more productive to use an explicit expression for the complex optical conductivity which can be derived using the Kubo formula or the RPA approach.Here, we present calculations of the dielectric function for an important case when the gap ε g between the conduction and valence bands is much smaller than the distance ε at (on the atomic scale) to other bands. The model is applicable to the IV-VI semiconductors (as PbTe, PbSe, and PbS), i.e., such narrow-gap semiconductors and semimetals, where the narrow gap appears as a result of intersections of two bands with different parity. We evaluate the dispersion of the real part of the dielectric function and the reflectance along with the behavior of the imaginary part around the absorption threshold. We find that the contribution of the electron transitions into the real part has the logarithmic singularity at the threshold and can be more essential for optical properties than absorption given by the imaginary part of the dielectric function.The effective Hamiltonian of the problem can be writ-ten as a 4×4 matrix 5

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Optical transitions inPbTe∕CdTequantum dots

Cited by 23 publications

References 23 publications

Local-moment magnetism in superconducting FeTe0.35Se0.65as seen via inelastic neutron scattering

Local-moment magnetism in superconducting FeTe0.35Se0.65as seen via inelastic neutron scattering

Optical Properties of PbS/CdS Core/Shell Quantum Dots

Features of interband absorption in the dielectric function of narrow-gap semiconductors

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