The issue addressed in the present SIRENA proposal is the quantitative modelling of heat transport at heterogeneous interfaces, i.e. interfaces between different materials. This situation is commonly encountered in present and future nanotechnologies. For instance, in integrated circuits, the heat generated in the transistor channel (silicon, SiGe, III-V) flows through several interfaces with other insulating/semiconductors materials towards the back side, and with metals of the interconnections towards the front side, respectively. Atomistic computer simulations are an invaluable tool to elucidate the thermal transport in nanostructures by focusing on the fundamental mechanisms of thermal exchange in targeted model systems. We propose atomistic simulations to achieve a breakthrough in the quantitative understanding of thermal interface resistance. To this end, we will combine first-principles molecular dynamics (FPMD) and a simulation framework developed recently to address heat conduction by molecular dynamics (MD) in large-scale systems, the approach to equilibrium molecular dynamics (AEMD). AEMD greatly reduces computational costs via the study of temperature transients. The proof of concept and benchmarking will be performed on two systems selected because i) their size and expected time-dependent thermal response are compatible with a first-principles treatment and ii) they have been studied recently by the most advanced experimental techniques of nanocharacterization, thereby providing an ideally suited experimental counterpart. The first system is an alkane self-assembled monolayer (SAM) sandwiched between a gold and a silicon surface, currently considered experimentally at the IBM Zurich Research Laboratory by B. Gotsmann. This system is particularly well suited for a proof of concept, as it appears that classical MD cannot provide a quantitative estimate of the thermal resistance in this case, due to the many different types of chemical bonds involved.
The second system is the interface of a chalcogenide glass, Ge2Sb2Te5 (GST) with a crystal or an amorphous material, following the study we made on another glass, GeTe4. In that case, published very recently (2017) the FPMD/AEMD methodology was put to good with a frank success to obtain the thermal conductivity. We shall focus on the thermal interface resistance at the interface between GST and silica/silicon thin films, by obtaining a fundamental parameter impacting the heat transfer in GST-PCM memories. The choice of glassy GST stems from the availability of FPMD structures for GST featuring different degrees of chemical order (amount of defects). By focusing on these two classes of systems (molecular interface layer and direct interface between two dense materials), we shall exploit at its best the capabilities of the FPMD/ AEMD approach in order to obtain a quantitative determination of prototypical interface thermal resistances in systems technologically relevant.
Madame Evelyne Lampin (Institut d'électronique, de microélectronique et de nanotechnologie)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IPCMS Institut de physique et chimie des matériaux de Strasbourg
IEMN Institut d'électronique, de microélectronique et de nanotechnologie
Help of the ANR 200,566 euros
Beginning and duration of the scientific project: December 2017 - 48 Months