Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Surface matters: Huge reduction of heat conduction observed in flat silicon channels

29.04.2015

The ability of materials to conduct heat is a concept that we are all familiar with from everyday life. The modern story of thermal transport dates back to 1822 when the French physicist Jean-Baptiste Joseph Fourier published his book “Théorie analytique de la chaleur” (The Analytic Theory of Heat), which became a cornerstone of heat transport. He pointed out that the thermal conductivity, i.e., ratio of the heat flux to the temperature gradient is an intrinsic property of the material itself.

The advent of nanotechnology, where the rules of classical physics gradually fail as the dimensions shrink, is challenging Fourier's theory of heat in several ways.

A paper published in ACS Nano and written by researchers from the Max Planck Institute for Polymer Research (Germany), the Catalan Institute of Nanoscience and Nanotechnology (ICN2, Spain) and the VTT Technical Research Centre of Finland (Finland) in the framework of the project MERGING (Membrane-based phonon engineering for energy harvesting) describes how the nanometer-scale topology and the chemical composition of the surface control the thermal conductivity of ultrathin silicon membranes.

The results show that the thermal conductivity of silicon membranes thinner than 10 nm is 25 times lower than that of bulk crystalline silicon and is controlled to a large extent by the structure and the chemical composition of their surface.

Combining state-of-the-art realistic atomistic modeling, sophisticated fabrication techniques, new measurement approaches and the latest parameter-free modeling, researchers unraveled the role of surface oxidation in determining the scattering of phonons (quantized lattice vibrations), which are the main heat carriers in silicon.

Both experiments and modeling showed that removing the native oxide improves the thermal conductivity of silicon nanostructures by almost a factor of two, while successive partial re-oxidation lowers it again.

Large-scale molecular dynamics simulations with up to 1,000,000 atoms allowed the researchers to quantify the relative contributions to the reduction of the thermal conductivity arising from the presence of native SiO2 and from the dimensionality reduction evaluated for a model with perfectly specular surfaces.

Silicon is the material of choice for almost all electronic-related applications, where characteristic dimensions below 10 nm have been reached, e.g. in the newest FET transistors, and heat dissipation control becomes essential for their optimum performance.

“The chemical nature of surfaces, therefore, emerges as a new key parameter for improving the performance of Si-based electronic and thermoelectric nanodevices”, says Dr. Davide Donadio. As a result, this work opens new possibilities for novel thermal experiments and designs directed to manipulate heat at the nanoscales.

Weitere Informationen:

http://www.mpip-mainz.mpg.de/Surface_matters_Donadio - Press release and original publication
http://www.mpip-mainz.mpg.de/theory_nanostructures - Information about Dr. Donadio and his research
http://www.mpip-mainz.mpg.de/home/en - Max Planck Institute for Polymer Research

Natacha Bouvier | Max-Planck-Institut für Polymerforschung

More articles from Materials Sciences:

nachricht New materials: Growing polymer pelts
19.11.2018 | Karlsruher Institut für Technologie (KIT)

nachricht Why geckos can stick to walls
19.11.2018 | Jacobs University Bremen gGmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Nonstop Tranport of Cargo in Nanomachines

20.11.2018 | Life Sciences

Researchers find social cultures in chimpanzees

20.11.2018 | Life Sciences

When AI and optoelectronics meet: Researchers take control of light properties

20.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>