Thermal conductivity of GaAs/AlAs superlattices

Capinski, William S.; Maris, Humphrey J.

doi:10.1016/0921-4526(95)00858-6

Cited by 152 publications

(76 citation statements)

References 2 publications

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“…However, quantitative analysis of the relative importance of these different mechanisms has not been completed yet and it is not clear which mechanism contributes most to the reduction of the thermal conductivity under different conditions. Experimental results [6,7] indicate that as the period of the superlattice decreases, the thermal conductivity along the cross-plane direction also decreases, and for very short period superlattice, its thermal conductivity could even fall below the alloy limit, i.e. if the two materials mixed homogeneously into an alloy.…”

Section: Introductionmentioning

confidence: 99%

“…Superlattice structures provide the possibility of decreasing materials' thermal conductivity while retaining their electrical conductivity, thus achieving a high thermoelectric figure-of-merit and improving the performance of thermoelectric devices. A large amount of experimental and theoretical work [3][4][5][6][7][8] has been carried out to study the effects of lattice period and interface on the thermal conductivity of various kinds of superlattice films. Results showed that the superlattice may have a much lower thermal conductivity than the value for each of the two materials composing the superlattice structure along both the in -plane and the cross-plane directions.…”

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics study of the lattice thermal conductivity of Kr/Ar superlattice nanowires

Chen

Yang

et al. 2004

Physica B: Condensed Matter

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The nonequilibrium molecular dynamics (NEMD) method has been used to calculate the lattice thermal conductivities of Ar and Kr/Ar nanostructures in order to study the effects of interface scattering, boundary scattering, and elastic strain on lattice thermal conductivity. Results show that interface scattering poses significant resistance to phonon transport in superlattices and superlattice nanowires. The thermal conductivity of the Kr/Ar superlattice nanowire is only about 1/3 of that for pure Ar nanowires with the same cross sectional area and total length due to the additional interfacial thermal resistance. It is found that nanowire boundary scattering provides significant resistance to phonon transport. As the cross sectional area increases, the nanowire boundary scattering decreases, which leads to increased nanowire thermal conductivity. The ratio of the interfacial thermal resistance to the total effective thermal resistance increases from 30% for the superlattice nanowire to 42% for the superlattice film. Period length is another important factor affecting the effective thermal conductivity of the nanostructures. Increasing the period length will lead to increased acoustic mismatch between the adjacent layers, and hence increased interfacial thermal resistance. However, if the total length of the superlattice nanowire is fixed, reducing the period length will lead to decreased effective thermal conductivity due to the increased number of interfaces. Finally, it is found that the interfacial thermal resistance decreases as the reference temperature increases, which might be due to the inelastic interface scattering. AbstractThe nonequilibrium molecular dynamics (NEMD) method has been used to calculate the lattice thermal conductivities of Ar and Kr/Ar nanostructures in order to study the effects of interface scattering, boundary scattering, and elastic strain on lattice thermal conductivity.Results show that interface scattering poses significant resistance to phonon transport in a yunfeichen@yahoo.com 2 superlattices and superlattice nanowires. The thermal conductivity of the Kr/Ar superlattice nanowire is only about 1/3 of that for pure Ar nanowires with the same cross sectional area and total length due to the additional interfacial thermal resistance. It is found that nanowire boundary scattering provides significant resistance to phonon transport. As the cross sectional area increases, the nanowire boundary scattering decreases, which leads to increased nanowire thermal conductivity. The ratio of the interfacial thermal resistance to the total effective thermal resistance increases from 30% for the superlattice nanowire to 42% for the superlattice film.Period length is another important factor affecting the effective thermal conductivity of the nanostructures. Increasing the period length will lead to increased acoustic mismatch between the adjacent layers, and hence increased interfacial thermal resistance. However, if the total length of the superlattice nanowire is fixed, reducing the p...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular dynamics study of the lattice thermal conductivity of Kr/Ar superlattice nanowires

Chen

Yang

et al. 2004

Physica B: Condensed Matter

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“…The thermal-conductivity tensor of a SL system reduces to two values: the in-plane thermal conductivity κ (inplane heat flow is assumed isotropic) and the crossplane thermal conductivity κ ⊥ . Experimental results have shown that, in SLs, the thermal conductivity is very anisotropic [65] (κ κ ⊥ ) while both κ and κ ⊥ are smaller than the weighted average of the constituent bulk materials [66][67][68][69][70]. Both effects can be attributed to the interfaces between adjacent layers [71,72].…”

Section: Active Core: a Iii-v Superlatticementioning

confidence: 80%

“…Apart from calculating the ITBR, an effective interface scattering rate τ −1 interface ( q) dependent on the same specularity parameter p spec ( q) is added to the internal scattering rate to calculate modified κ (see detailed derivations in [48]). By adjusting only ∆, typically between 1-2Å, the calculated thermal conductivity using this model fits a number of different experiments [66,68,69].…”

Section: Twofold Influence Of Effective Interface Roughnessmentioning

confidence: 99%

Quantum Cascade Lasers: Electrothermal Simulation

Piprek¹

2017

Handbook of Optoelectronic Device Modeling and Simulation

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“…Depending on boundary roughness, phonon may exhibit the mirror (specular) reflection or the diffuse reflection, when it is scattered in all directions [22]. That is why in multi-layered structures, thermal conductivity in the direction perpendicular to layer boundaries is considerably reduced compared to the weighted average of bulk values of constituent layers [23][24][25]. Besides, a distinct anisotropy in the thermal conductivity is observed.…”

Section: Thermal Vcsel Modelsmentioning

confidence: 99%

Principles of VCSEL designing

Nakwaski

2008

Opto-Electronics Review

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Comprehensive computer simulations are currently the most efficient and cheap methods in designing and optimisation of semiconductor device structures. Seemingly they should be as exact as possible, but in practice it is well known that the most exact approaches are also the most involved and the most time-consuming ones and need powerful computers. In some cases, cheaper somewhat simplified modelling simulations are sufficiently accurate. Therefore, an appropriate modelling approach should be chosen taking into account a compromise between our needs and our possibilities.Modelling of operation and designing of structures of vertical-cavity surface-emitting diode lasers (VCSELs) requires appropriate mathematical description of physical processes crucial for devices operation, i.e., various optical, electrical, thermal, recombination and sometimes also mechanical phenomena taking place within their volumes. Equally important are mutual interactions between above individual processes, usually strongly non-linear and creating a real network of various inter-relations.Chain is as strong as its weakest link. Analogously, model is as exact as its less exact part. Therefore it is useless to improve exactness of its more accurate parts and not to care about less exact ones. All model parts should exhibit similar accuracy. In any individual case, a reasonable compromise should be reached between high modelling fidelity and its practical convenience depending on a main modelling goal, importance and urgency of expected results, available equipment and also financial possibilities. In the present paper, some simplifications used in VCSEL modelling are discussed and their impact on exactness of VCSEL designing is analysed.

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Thermal conductivity of GaAs/AlAs superlattices

Cited by 152 publications

References 2 publications

Molecular dynamics study of the lattice thermal conductivity of Kr/Ar superlattice nanowires

Molecular dynamics study of the lattice thermal conductivity of Kr/Ar superlattice nanowires

Quantum Cascade Lasers: Electrothermal Simulation

Principles of VCSEL designing

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