At the nanoscale, heat transport is strongly influenced by boundaries, interfaces and contacts.

Nanostructured and molecular materials have specific thermal transport properties, which can be tuned for various applications. We study thermal conductance through nanoscale mechanical contacts, through molecules or vacuum gaps using scanning thermal microscopy, and through nanowire devices using MEMS-based sensors.

Highlights

Mapping

Heat transport through atomic contacts

N. Mosso et al.
Nature Nanotechnology 12, 430-433, 2017.

Heat transport and dissipation at the nanoscale severely limit the scaling of high-performance electronic devices and circuits. Metallic atomic junctions serve as model systems to probe electrical and thermal transport down to the atomic level as well as quantum effects that occur in one-dimensional (1D) systems. Here we report heat-transfer measurements through atomic junctions and analyse the thermal conductance of single-atom gold contacts at room temperature. Simultaneous measurements of charge and heat transport reveal the proportionality of electrical and thermal conductance, quantized with the respective conductance quanta6. This constitutes a verification of the Wiedemann–Franz law at the atomic scale.

Mapping

Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

F. Menges et al.
Arxiv ID:1512.09050, 2016.

The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is studied using a vacuum-based scanning thermal microscope. The temperature and distance dependence was quantified for both states of the vanadium dioxide film.

Length-dependent thermal transport through molecular chains

Length-dependent thermal transport through molecular chains

T. Meier et al.
Physical Review Letters 113, 060801, 2014.

We present heat-transport measurements conducted with a vacuum-operated scanning thermal microscope to study the thermal conductance of monolayers of nine different alkane thiols self-assembled on Au(111) surfaces as a function of their length (2 to 18 methylene units). We found a conductance variance of up to a factor of 3 as a function of alkane chain length, with maximum conductance for a chain length of four carbon atoms.

Full thermoelectric characterization

Full thermoelectric characterization of InAs nanowires using MEMS heater/sensors

S.F. Karg et al.
Nanotechnology 25(30) 305702, 2014.

Precise measurements of a complete set of thermoelectric parameters on a single indium-arsenide nanowire (NW) have been performed using highly sensitive, micro-fabricated sensing devices based on the heater/sensor principle.

Thermal Transport into Graphene

Thermal Transport into Graphene through Nanoscopic Contacts

F. Menges et al.
Physical Review Letters 111, 205901, 2013.

We probe local heat transfer into graphene by high-resolution scanning thermal microscopy on amorphous silicon oxide (SiO2) and crystalline silicon carbide (SiC) using scanning thermal microscopy. We quantify thickness-dependent thermal resistance modulations at sub-10-nm lateral resolution and thermal sensitivity for the individual atomic layers. We observe a decrease of thermal resistance with increasing number of graphene layers and attribute this trend to the spreading of heat using the thickness dependence of graphene’s thermal conductivity.

Measurement of Thermoelectric Properties

Measurement of Thermoelectric Properties of Single Semiconductor Nanowires

S. Karg et al.
J. Electron. Mater. 42(7) 2409-2414, 2013.

We evaluated a self-heating method to determine the thermal conductivity of individual silicon and indium arsenide (InAs) nanowires. Furthermore, electrical conductivity and Seebeck coefficient (thermopower) were measured.

Quantized thermal transport

Quantized thermal transport across contacts of rough surfaces

B. Gotsmann, M. A. Lantz et al.
Nature Materials 12, 59-65, 2013.

Heat transport across interfaces is often discussed in terms of the transmission probability of the heat-carrying phonons through the contact zone. Here, we report experimental data on the pressure dependence of thermal transport across polished nanoscale contacts. The data can be quantitatively explained by a model of thermal conductance across interfaces that incorporates the effect of nanoscale roughness through the quantized thermal conductance across individual atomic-scale contacts within the contact zone.

High resolution vacuum

High resolution vacuum scanning thermal microscopy of HfO2 and SiO2

M. Hinz et al.
Applied Physics Letters 92(4) 043122, 2008.

We present scanning thermal microscopy (SThM) measurements on a sample consisting of regions of 3-nm-thick HfO2 film and 2-nm-thick SiO2 on a silicon substrate. The experiments were preformed in high vacuum conditions using microfabricated silicon cantilevers with sharp heatable tips, facilitating the unprecedented achievement of a lateral SThM image resolution of 25 nm. In addition, the heat transfer through the tip to the sample was investigated using approach curves and used to determine the thermal conductivity of the 3-nm-thick HfO2 layer.

Nano-Thermomechanics

Nano-Thermomechanics: Fundamentals and Application in Data Storage Devices

B. Gotsmann, U. Dürig
In “Applied Scanning Probe Methods IV: Industrial Applications,” B. Bushan and H. Fuchs (Eds.), pp. 215-250, Springer, Berlin, Heidelberg, 2006.

The interplay between thermal and mechanical properties of solids is a fascinating topic of research in materials science and certainly has numerous applications. In particular, mechanical polymer properties show both complex and interesting dependencies on temperature. There is a clear trend of extending such research down to the nanoscale, which is nurtured by the necessity to understand nanoscale properties in order to tailor materials for nanoscale applications.

Heatable probes

Nanoscale thermal and mechanical interactions studies using heatable probes

B. Gotsmann et al.
Nanotechnology, Wiley, 2010.

The use of heatable probes in scanning probe microscopy allows the effect of temperature to be studied in combination with the mechanical interaction of the probe tip with a sample surface. Using nanometer-scale sharp tips, the thermal and thermomechanical properties of solids can be determined locally down to nanometer scale.

Projects & collaborations

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EU project Molesco

MOLESCO
EU project Molecular-Scale Electronics


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Swiss Federal Council


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Swiss National Science Foundation

Bernd Gotsmann

Bernd Gotsmann

IBM Research scientist

Nico Mosso

Nico Mosso

IBM Research scientist

Fabian Koenemann

Fabian Koenemann

IBM Research scientist