Band structure analysis in SiGe nanowires

Amato, Michele; Palummo, Maurizia; Ossicini, Stefano

doi:10.1016/j.mseb.2011.10.008

Cited by 15 publications

(12 citation statements)

References 66 publications

(132 reference statements)

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“…It reproduces exactly the Lamé-Clapeyron-Navier equation of an elastically isotropic material, equation (4). Hence, as the boundary conditions are invariant under a rotation around the NW axis (this is due to the invariance of the stiffness tensor noted above), the general solution for equation (9) is the same as that of equation (4), u z (z) = Cz and u r (r) = Ar + Br 2 c /r.…”

Section: Calculationmentioning

confidence: 69%

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Strain in crystalline core-shell nanowires

Ferrand

Cibert

2014

Eur. Phys. J. Appl. Phys.

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Abstract. We propose a comprehensive description of the strain configuration induced by the lattice mismatch in a core-shell nanowire with circular cross-section, taking into account the crystal anisotropy and the difference in stiffness constants of the two materials. We use an analytical approach which fully exploits the symmetry properties of the system. Explicit formulae are given for nanowires with the wurtzite structure or the zinc-blende structure with the hexagonal/trigonal axis along the nanowire, and the results are compared to available numerical calculations and experimental data on nanowires made of different III-V and II-VI semiconductors. The method is also applied to multishell nanowires, and to core-shell nanowires grown along the 0 0 1 axis of cubic semiconductors. It can be extended to other orientations and other crystal structures.

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Section: Calculationmentioning

confidence: 69%

“…The strain can also be designed to induce a built-in piezoelectric field, resulting in a faster separation of the electron-hole pairs in photovoltaic applications [3]. Finally, strain is an important parameter when engineering Si-Ge NWs to obtain direct bandgap configurations and efficient emission of light [4].…”

Section: Introductionmentioning

confidence: 99%

Strain in crystalline core-shell nanowires

Ferrand

Cibert

2014

Eur. Phys. J. Appl. Phys.

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“…A brief discussion on the spatial variation of bands, bandstructure and band offsets with change in doping concentration and manipulation of relative concentrations of Si and Ge in Si x Ge 1−x heterostructures is carried out in Refs. [58][59][60][61] . In fabricated heterojunctions, the effect of inhomogeneous doping, disorder and unequal work functions smoothens out thin energy barriers 30,48,49 into Gaussian/bell-shaped profiles.…”

Section: Transport Formulationmentioning

confidence: 99%

Incoherent scattering can favorably influence energy filtering in nanostructured thermoelectrics

Singha

Muralidharan

2017

Sci Rep

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Investigating in detail the physics of energy filtering through a single planar energy barrier in nanostructured thermoelectric generators, we reinforce the non-trivial result that the anticipated enhancement in generated power at a given efficiency via energy filtering is a characteristic of systems dominated by incoherent scattering and is absent in ballistic devices. In such cases, assuming an energy dependent relaxation time τ(E) = kE r, we show that there exists a minimum value r min beyond which generation can be enhanced by embedding nanobarriers. For bulk generators with embedded nanobarriers, we delve into the details of inter sub-band scattering and show that it has finite contribution to the enhancement in generation. We subsequently discuss the realistic aspects, such as the effect of smooth transmission cut-off and show that for r > r min, the optimized energy barrier is just sufficiently wide enough to scatter off low energy electrons, a very wide barrier being detrimental to the performance. Analysis of the obtained results should provide general design guidelines for enhancement in thermoelectric generation via energy filtering. Our non-equilibrium approach is typically valid in the absence of local quasi-equilibrium and hence sets the stage for future advancements in thermoelectric device analysis, for example, Peltier cooling near a barrier interface.

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“…[26][27][28] Amato et al studied structure stabilities, electronic properties, and quantum connement effects of the different types of SiGe NW based on rst-principle calculations. [29][30][31][32][33] They predicted that the Ge core Si shell NW are very stable energetically, and that efficient electron and hole doping can be easily realized because of the band offset in the type-II heterojunction of the Ge core Si shell NW. 34,35 Following Amato's work, we have systematically studied substitution doping in various compositionally abrupt Si/Ge NW using the rst-principle method because of the presence of type-II band offsets in other types of compositionally abrupt Si/Ge NW in addition to the Ge core Si shell NW.…”

Section: Introductionmentioning

confidence: 99%