Abstract:Electronic band-edge structure and optical properties of Si 1−x Ge x are investigated theoretically emloying a full-potential linearized augmented plane wave (FPLAPW) method. The exchange-correlation potential in the local density approximation (LDA) is corrected by an on-site Coulomb potential (i.e., within the LDA+U SIC approach) acting asymmetrically on the atomic-like orbitals in the muffin-tin spheres. The electronic structure of the Si 1−x Ge x is calculated self-consistently, assuming a T d symmetrized … Show more
“…Density functional theory in the local-density approximation as used by Gavrilenko et al [47] shows in general deviations from experimental data near the band gap. Valence-band states in semiconductors contributing to the electronic ground state density tend to agree with experimental shapes, although the total valence-band width may be smaller [48][49][50], which is similarly observed here comparing the calculated DOS with the RIXS differences for 6H-SiC. Note that more recent DOS calculations on 6H-SiC (for example [51,52]) find similar s-DOS and p-DOS as obtained from the calculations by Gavrilenko et al [47].…”
Electron-phonon scattering has been studied for silicon carbide (6H-SiC) with resonant inelastic x-ray scattering at the silicon 2p edge. The observed electron-phonon scattering yields a crystal momentum transfer rate per average phonon in 6H-SiC of 1.8 fs −1 while it is 0.2 fs −1 in crystalline silicon. The angular momentum transfer rate per average phonon for 6H-SiC is 0.1 fs −1 , which is much higher than 0.0035 fs −1 obtained for crystalline silicon in a previous study. The higher electron-phonon scattering rates in 6H-SiC are a result of the larger electron localization at the silicon atoms in 6H-SiC as compared to crystalline silicon. While delocalized valence electrons can screen effectively (part of) the electron-phonon interaction, this effect is suppressed for 6H-SiC in comparison to crystalline silicon. Smaller contributions to the difference in electron-phonon scattering rates between 6H-SiC and silicon arise from the lower atomic mass of carbon versus silicon and the difference in local symmetry.
“…Density functional theory in the local-density approximation as used by Gavrilenko et al [47] shows in general deviations from experimental data near the band gap. Valence-band states in semiconductors contributing to the electronic ground state density tend to agree with experimental shapes, although the total valence-band width may be smaller [48][49][50], which is similarly observed here comparing the calculated DOS with the RIXS differences for 6H-SiC. Note that more recent DOS calculations on 6H-SiC (for example [51,52]) find similar s-DOS and p-DOS as obtained from the calculations by Gavrilenko et al [47].…”
Electron-phonon scattering has been studied for silicon carbide (6H-SiC) with resonant inelastic x-ray scattering at the silicon 2p edge. The observed electron-phonon scattering yields a crystal momentum transfer rate per average phonon in 6H-SiC of 1.8 fs −1 while it is 0.2 fs −1 in crystalline silicon. The angular momentum transfer rate per average phonon for 6H-SiC is 0.1 fs −1 , which is much higher than 0.0035 fs −1 obtained for crystalline silicon in a previous study. The higher electron-phonon scattering rates in 6H-SiC are a result of the larger electron localization at the silicon atoms in 6H-SiC as compared to crystalline silicon. While delocalized valence electrons can screen effectively (part of) the electron-phonon interaction, this effect is suppressed for 6H-SiC in comparison to crystalline silicon. Smaller contributions to the difference in electron-phonon scattering rates between 6H-SiC and silicon arise from the lower atomic mass of carbon versus silicon and the difference in local symmetry.
“…To calculate the principal energy gaps for the zinc-blende structure of Si 1-x Ge x at 300 K for concentration x < 0.85, we have used the interpolation equation like 1.12-0.41x + 0.008x 2 eV, but for x > 0.85 we have used the linear 1.86 -1.2x eV. From these calculations one can state that the Si 1-x Ge x is a Si-like indirect semiconductor for x < 0.85 in good agreement with other results [25].…”
Section: Electronic Band Structure Of the Si 1-x Ge X Alloysupporting
An investigation into the structural, electronic and optical properties of Si, Ge, and Si 1-x Ge x for different compositions was conducted using first-principles calculations based on density functional theory (DFT). The total energies were calculated within the full-potential linear muffin-tin orbital (FP-LMTO) method augmented by a plane-wave basis (PLW), implemented in Lmtar code. The effects of the approximations to the exchange-correlation energy were treated by the local density approximation (LDA). From our simulation results, it is found that the theoretical ground-state parameters, the band structure, the density of states (DOS), the chemical bonding and the optical properties agree well with the experiment and other theoretical calculations. The accuracies found from the present calculations allow us to describe the properties of the electronic as well as the optoelectronic devices based on the Si 1-x Ge x alloy.
“…In general, the bandgaps relevant to the semiconductor alloys adopt one of the following four behaviors: (i) bowing behavior, as is found for the common-cation III-V and II-VI alloys [17]; (ii) linear behavior, as in the case of common-anion alloys [18]; (iii) band anti-crossing, as occurs in indirect-bandgap-based alloys (such as Si x Ge 1−x−y Sn y [5][6][7], Al x Ga 1−x As [19] and GaP x As 1−x [20]); and (iv) anomalous behavior, exemplified by the metallization observed in the highly lattice-mismatched nitride IIIV 1−x N x alloys [21][22][23]; the negative bowing behavior seen in the alloys of In x Ga 1−x As [24] and GaSb x As 1−x [25]; the anomalous behavior reported for lead chalcogenides [26], where the direct gap is found to be at the L high-symmetry point of the Brillouin zone.…”
Section: Introductionmentioning
confidence: 94%
“…On the other hand, the II-VI semiconductor alloys remain the predominantly used materials in the opto-electronics field (e.g., the ternary and quaternary alloys of the Cd(Zn)Te(Se) family) [3,4]. It has also proven possible to tune the properties of the elementary semiconductor alloys Si x Ge 1−x−y Sn y for a diversity of telecommunication applications [5][6][7].…”
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