Anisotropic Thermal Conductivity of a Si/Ge Quantum Dot Superlattice

2000 ◽  
Author(s):  
Theodorian Borca-Tasciuc ◽  
Weili Liu ◽  
Jianlin Liu ◽  
Kang L. Wang ◽  
Gang Chen
Keyword(s):  
Thermal Conductivity ◽  
Quantum Dots ◽  
Molecular Beam ◽  
Conductivity Measurements ◽  
Transport Models ◽  
3Ω Method ◽  
Superlattice Structure ◽  
Anisotropic Thermal Conductivity ◽  
Ge Quantum Dot

Abstract In this work, we present experimental results on the in-plane and cross-plane thermal conductivity characterization of a Si/Ge quantum-dots superlattice structure. The quantum-dots superlattice was grown by molecular-beam-epitaxy and self-organization. The anisotropic thermal conductivity measurements are performed by a differential two-wire 3ω method. The measured in-plane and cross-plane thermal conductivity values show a different temperature behavior. The results are compared and explained with heat transport models in superlattices.

Anisotropic Thermal Conductivity of A Si/Ge Superlattice

1998 ◽  
Vol 545 ◽  
Author(s):  
T. Borca-Tasciuc ◽  
D. Song ◽  
J. L. Liu ◽  
G. Chen ◽  
K. L. Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Temperature Drop ◽  
Differential Method ◽  
Conductivity Measurements ◽  
3Ω Method ◽  
Anisotropic Thermal Conductivity ◽  
Plane Direction ◽  
Narrow Width ◽  
Heat Spreading

AbstractExperimental evidence for a significant thermal conductivity reduction have been reported in recent years for GaAs/AlAs, Si/Ge, and Bi 2Te3/Sb2Te3 superlattices. In this work, we present preliminary experimental results on the reduction of the in-plane and cross-plane thermal conductivity for a symmetric Si/Ge superlattice. A differential 2-wire 3ω method is developed to perform the anisotropic thermal conductivity measurements. In this technique, a patterned heater with a width much larger than the film thickness yields the cross-plane thermal conductivity of the film. The in-plane thin film thermal conductivity is inferred from the temperature rise of a narrow width heater that can create more heat spreading in the in-plane direction of the thin film. A differential method to measure the temperature drop across the film is employed in order to increase the accuracy of the measurement.

Synthesis and Physical Properties of Skutterudite Superlattices

2000 ◽  
Vol 626 ◽  
Author(s):  
Joshua R. Williams ◽  
David C. Johnson ◽  
Michael Kaeser ◽  
Terry Tritt ◽  
George Nolas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Physical Properties ◽  
High Temperatures ◽  
Synthesis And Characterization ◽  
Superlattice Structure

ABSTRACTPredicted and observed reductions in thermal conductivity of materials with superlattice structure have prompted interesting research into the possibility of using these materials as higher efficiency thermoelectrics. Synthesis of superlattice materials is challenging however, as the structure itself is generally not very stable at high temperatures as it is prone to interdiffusion. Presented here is the successful synthesis and characterization of a superlattice composed of two materials with the skutterudite structure, IrSb3 and CoSb3.

Hybrid Thermal Behavior from Thermoelectrics to Heat Sinking of a Thin Si Membrane with Stretched Ge Quantum Dots

2010 ◽  
Vol 1267 ◽  
Author(s):  
Jean-Numa Gillet
Keyword(s):  
Thermal Conductivity ◽  
Quantum Dots ◽  
Thermal Behavior ◽  
Heat Propagation ◽  
Peltier Effect ◽  
Orthogonal Direction ◽  
Thermal Insulating ◽  
Anisotropic Thermal Conductivity ◽  
Ge Quantum Dots ◽  
Heat Sinking

AbstractA membranous nanomaterial showing, for the first time, a hybrid thermal behavior between insulating and dissipative regimes is proposed with applications in both thermoelectrics (low thermal conductivity) and passive heat sinking (high thermal conductivity). While other compounds could be chosen, the nanomaterial is made up of a thin Si membrane covered by Ge quantum dots (QDs) with epitaxial facets. The QDs are voluntarily stretched in the direction [010] or y parallel to the membrane to form elongated islands. The broken symmetry induces an exalted phonon wave-guiding in y. Therefore, when hot and cold junctions are connected to the membrane following the stretching direction [010], the anisotropic thermal conductivity shows a significant exaltation with respect to the in-plane orthogonal direction [100] or x, where the Ge islands have the smallest average size. An example nanomaterial is obtained by repetition of molecular supercell slabs containing 4348 atoms each. The thermal conductivity shows a marked exaltation higher than 22 folds, from 1.5 to 33.5 W/m/K when the connection direction between the hot and cold junctions is rotated by 90° from x to y. Therefore, the nanomaterial presents a changing thermal behavior from insulation to passive dissipation when the heat propagation direction is modified from x to y. As a result, it could be used for the design of passive heat sinkers (from the phonons) when the two junctions are connected following [010]. In contrast, a thermal insulating behavior appears when the junctions are linked following [100]. This direction can be as well used for cooling applications. However, in this case, cooling is differently generated using the Peltier effect (from the electrons). Seebeck generation can be also envisioned in the direction [100].

Growth and Characterization of Inas Quantum Dots on Silicon

1999 ◽  
Vol 583 ◽  
Author(s):  
L. Hansen ◽  
A. Ankudinov ◽  
F. Bensing ◽  
J. Wagner ◽  
G. Ade ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
The Other ◽  
Material System ◽  
Inas Quantum Dots ◽  
New Material ◽  
The One ◽  
Insight Into

AbstractUp to 1011 cm−2 InAs quantum dots (QD) can be grown on Silicon(001) by molecular beam epitaxy. This very new material system is on the one hand interesting with regard to the integration of optoelectronics with silicon technology on the other hand it offers new insight into the formation of QDs. We report on RHEED, TEM and Raman studies about (in-) coherence of the QDs and on an according to our knowledge so far unknown dewetting transition in this material system. The results are being discussed on the basis of a thermodynamic model, assuming a liquid-like behavior of a strained adlayer.

scholarly journals Self Assembly of semiconductor nanostructures

Respuestas ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 47-51
Author(s):  
Máximo López-López ◽  
Esteban Cruz-Hernández ◽  
Isaac Martínez-Velis ◽  
Juan Salvador Rojas-Ramírez ◽  
Manolo Ramirez-Lopez ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Molecular Beam Epitaxy ◽  
Self Assembly ◽  
Molecular Beam ◽  
Quantum Wires ◽  
Preferential Growth ◽  
Growth Method ◽  
Strong Surface ◽  
Self Assembled

 Abstract In this work we present the growth and characterization of GaAs self-assembled quantum wires (SAQWRs), and InAs self-assembled quantum dots (SAQDs) by molecular beam epitaxy on (631)-oriented GaAs substrates. Adatoms on the (631) crystal plane present a strong surface diffusion anisotropy which we use to induce preferential growth along one direction to produce SAQWRs. On the other hand, InAs SAQDs were obtained on GaAs(631) with SAQWRs by the Stransky–Krastanov (S-K) growth method. SAQDs grown directly on (631) substrates presented considerable fluctuations in size. We study the effects of growing a stressor layer before the SAQDs formation to reduce these fluctuations.Keywords : Quantum wires, quantum dots; selfassembly; molecular beam epitaxy.

scholarly journals Measurement of anisotropic thermal conductivity of a dense forest of nanowires using the 3ω method

2018 ◽  
Vol 89 (8) ◽  
pp. 084902 ◽  
Author(s):  
Dhruv Singhal ◽  
Jessy Paterson ◽  
Dimitri Tainoff ◽  
Jacques Richard ◽  
Meriam Ben-Khedim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
3Ω Method ◽  
Dense Forest ◽  
Anisotropic Thermal Conductivity
Sign in / Sign up

Export Citation Format

Share Document