On the interplay between phonon-boundary scattering and phonon-point-defect scattering in SiGe thin films

Iskandar, Alexander A.; Abou-Khalil, A.; Kazan, M.; Kassem, Wassim; Volz, Sébastian

doi:10.1063/1.4915948

Cited by 14 publications

(13 citation statements)

References 49 publications

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“…Significant progress took place when Garg et al demonstrated the viability of first principle approaches to estimate the bulk thermal conductivity of SiGe [6]. Recently, Iskandar modeled thin SiGe films to include the effect of boundary modes [7].…”

Section: Introductionmentioning

confidence: 99%

Unifying first-principles theoretical predictions and experimental measurements of size effects in thermal transport in SiGe alloys

Huberman

Chiloyan

Duncan

et al. 2017

Phys. Rev. Materials

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In this work, we demonstrate the correspondence between first principle calculations and experimental measurements of size effects on thermal transport in SiGe alloys. Transient thermal grating (TTG) is used to measure the effective thermal conductivity. The virtual crystal approximation under the density functional theory (DFT) framework combined with impurity scattering is used to determine the phonon properties for the exact alloy composition of the measured samples. With these properties, classical size effects are calculated for the experimental geometry of reflection mode TTG using the recently-developed variational solution to the phonon Boltzmann transport equation (BTE), which is verified against established Monte Carlo simulations. We find agreement between theoretical predictions and experimental measurements in the reduction of thermal conductivity (as much as ∼ 25% of the bulk value) across grating periods spanning one order of magnitude. This work provides a framework for the tabletop study of size effects on thermal transport. * gchen2@mit.edu 1 arXiv:1704.01386v2 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Unifying first-principles theoretical predictions and experimental measurements of size effects in thermal transport in SiGe alloys

Huberman

Chiloyan

Duncan

et al. 2017

Phys. Rev. Materials

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“…Diffusive transport assumption remains valid if the heat source dimension a is bigger than the carrier mean free path (MFP), l. That is if the system Knudsen number (Kn = l/a) is smaller than 1 (Kn << 1). In our system, phonon MFP is greatly reduced compared to bulk values due to interface scattering and impurities [164].…”

Section: Thermal Transport In Anisotropic Mediamentioning

confidence: 89%

“…It is also possible that the Ge content does not increase linearly inside the layer and that some Ge accumulated at the top. Finally, we model thermal conductivity using bulk thermal conductivity values whereas this value can be greatly reduced in thin film [164,175].…”

Section: Thermal Transport In Anisotropic Mediamentioning

confidence: 99%

“…As we will explain in the following section, the thermal spreading resistance of a layer on a substrate is expected to increase (decrease) if the thermal conductivity of the layer is smaller (larger) than that of the substrate ( k layer k substrate < 1 or > 1). Therefore, the resistance lowering observed in the Si 1−x Ge x region is counter intuitive as, for any Ge content, the thermal conductivity of Si 1−x Ge x is always lower than that of silicon [164]. However, the Ge content is varying from around 80% to 100%.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative Mapping of Nanothermal Transport via Scanning Thermal Microscopy

Spiece¹

2019

Springer Theses

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This thesis is the fruit of many coincidences and collaborations without which it wouldn't have been born. So therefore, there shouldn't be any particular order of importance such as in a puzzle, removing one piece makes the picture incomplete. The contributions and impact of each of the following people cannot be completely pictured in few words, therefore the easiest is just thank you all. Right so, always there to provide me with endless support, trust and energy, my supervisor Oleg Kolosov has been at the core of my work since the first days, and even before that. Long discussions, late emails and endless nights playing in the lab, he taught me more I'll probably ever realise, beyond the sole scientific realm.

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“…Thus, the increased scattering events of heat carriers significantly reduce the thermal conductivity and give rise to important thermal issues, primarily stability. 14,15 The ability to effectively dissipate heat is therefore a crucial limiting factor in integrated photonic circuit design, due to the fact that device functionality and performance strongly depend on the temperature. In particular, for semiconductor coherent light sources, the yield usually decreases above room temperature while the threshold current increases rapidly with temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity of epitaxially grown InP: experiment and simulation

et al. 2017

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The integration of III-V optoelectronic devices on silicon is confronted with the challenge of heat dissipation for reliable and stable operation. A thorough understanding and characterization of thermal transport is paramount for improved designs of, for example, viable III-V light sources on silicon. In this work, the thermal conductivity of heteroepitaxial laterally overgrown InP layers on silicon is experimentally investigated using microRaman thermometry. By examining InP mesa-like structures grown from trenches defined by a SiO 2 mask, we found that the thermal conductivity decreases by about one third, compared to the bulk thermal conductivity of InP, with decreasing width from 400 to 250 nm. The high thermal conductivity of InP grown from 400 nm trenches was attributed to the lower defect density as the InP microcrystal becomes thicker. In this case, the thermal transport is dominated by phonon-phonon interactions as in a low defect-density monocrystalline bulk material, whereas for thinner InP layers grown from narrower trenches, the heat transfer is dominated by phonon scattering at the extended defects and InP/ SiO 2 interface. In addition to the nominally undoped sample, sulfur-doped (1 × 10 18 cm −3) InP grown on Si was also studied. For the narrower doped InP microcrystals, the thermal conductivity decreased by a factor of two compared to the bulk value. Sources of errors in the thermal conductivity measurements are discussed. The experimental temperature rise was successfully simulated by the heat diffusion equation using the FEM.

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On the interplay between phonon-boundary scattering and phonon-point-defect scattering in SiGe thin films

Cited by 14 publications

References 49 publications

Unifying first-principles theoretical predictions and experimental measurements of size effects in thermal transport in SiGe alloys

Unifying first-principles theoretical predictions and experimental measurements of size effects in thermal transport in SiGe alloys

Quantitative Mapping of Nanothermal Transport via Scanning Thermal Microscopy

Thermal conductivity of epitaxially grown InP: experiment and simulation

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