Nanoscale Thermal Transport
What we do
Heat dissipation and thermal management are central challenges in various areas of science and technology and consist of critical issues in the majority of nanoelectronic devices. However, with the continuous miniaturization of electronic devices reaching physical limits, heat transport and thermal management are becoming increasingly more challenging.
Our team has developed high-resolution optical and electrical characterization techniques to investigate thermal properties of materials of high technological importance, such as semiconductor nanostructures, i.e., Si based membrane structures, phononin crystals (PnCs), nanowires, superlattices and two-dimensional (2D) materials. Moreover, we have demonstrated efficient ways to control heat propagation in nanomaterials by engineering the phononic properties of their fundamental components.
•Seebeck Coefficient & Electric conductivity measurement
•Scanning thermal microscopy
•FT-IR thermometry (collaboration with ALBA)
•Optical transmission phase change
Phononic crystals: PnCs structures with characteristic sizes reported to show coherent effects in the hypersound have been found to exhibit reduced in-plane thermal conductivity, κ, values. Moreover, it has been seen that, for a given membrane thickness, the temperature evolution, κ(T), from room temperature to about 1000 K can be effectively tuned and approaching to a regime where κ is almost insensitive to T by changing the neck distance in between holes. The latter reflects the increasing role of surface scattering on k(T) by limiting the phonon mean free path at expenses of the phonon-phonon scattering. Control and manipulation of heat transport requires devices with analogous functionalities as diodes and transistors in electronics, therefore thermal circuits could be devised but, also used in thermal management and thermoelectric energy generation. This work benefits from European collaborations and membership of the European CRS network on Thermal Nanoscience and Nanoengineering. During this period we will study the tuning of k(T) in “holey” membranes as a mechanism to introduce heat transfer directionality towards efficient and direction controlled heat dissipation and thermal diode and transistor concepts.
2D materials: 2D atomic crystals have become leading topic in different research areas and a strategic research subject at ICN2 level. In the P2N group, we have already started to work in the heat transport properties of some of these materials mainly in the framework of the Severo Ochoa internal program. Our purpose is to expand the present research to the study of the mechanical properties of 2D materials and investigate, both, the thermal and mechanical properties of heterostructures made by assembling different 2D crystals, foreseeing the possibility of obtaining properties in the stacked assembly distinct from its component materials.
The team is developing experimental methods for the characterization of thermal properties in fluids. These techniques will allow us the establishment of new research on the modification of the thermal properties of a base fluid upon the incorporation of nanoparticles.
A. El Sachat et al., ACS Applied Polymer Materials 2020, 2, 2, 487-496.
A. El Sachat et al., 2D Materials, 6, 2, 2019.
A. El Sachat et al., Nanotechnology, 28, 50, 2017.
B. Graczykowski, A. El Sachat et al., Nature Communication, 8, 415, 2017.